Atiato TURBINE -DRIVEN GENERATORS IN THE VICTORIA FALLS ...

AtiatoTURBINE -DRIVEN GENERATORS IN THE VICTORIA FALLS POWER STATION (See page 417)

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September, 1946 NEWNES PRACTICAL MECHANICS

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412 NEWNES PRACTICAL MECHANICS September, 1946

PREPARE FOR PEACE -TIME COMPETITIONIn the more competitive days of peace, technical training will be a vital necessitr.to theEngineer who wishes to safeguard his position and make advancement. " ENGINEERINGOPPORTUNITIES " will show you how to secure this all-important technical trainingquickly and easily in your spare time. This 100 -page book is full of valuable informationand explains the simplest way of preparing for recognised Examinations. Among thecourses described are :

MECHANICAL ENGINEERING GROUPA.M.I.Mech.E. EstimatingCity & Guilds Foremanship

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General Mechanical Eng. Jig & Tool Design General Electrical Eng. Electrical DesignDiesel Engines Viewing & Inspection Alternating Currents IlluminationDraughtsmanship & Tracing Welding Power House Design InstallationsWorks ManagementPress Tool Work

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Copyright in all drawings, photographs and articlespublished in " Practical Mechanics " is speciallyreserred throughout the countries signatory to theBerns Convention and the U.S.A. Reproductionsor imitations of any of these are therefore

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FAIR COMMENT

PRACTICALMECHANICS

Owing to the paper shortage "The Cyclist," "Practical Motorist," and "Home Movies" aretemporarily incorporated.

Editor: F. J. CAMM

VOL. XIII SEPTEMBER, 1946 No. 156

The Model Engineer ExhibitionOUR readers are cordially invited to visit

our Stand No. 14 at the ModelEngineer Exhibition now running at

the Horticultural Hall. Apart from thefull range of our technical periodicals andbooks, as well as blueprints, which we shallexhibit, readers will be able 'to inspect mynew automatic pump for bicycles and motor-cars which inflates the tyres as you go along.

The pump will be shown fitted to anordinary bicycle. It may be attached to anybicycle by means of two screws, and thepumps will keep the tyres inflated even whenthey are punctured. A valve is incorporatedto ensure that the tyres are not over -inflated.It is almost effortless in operation. Its greatadvantage is that it may be attached to anybicycle without structural alteration of anysort, and it represents a most important stepforward in pneumatic tyre technique.

Our telephone number at the exhibitionis Victoria 3385, and the attendants will beable to inform readers as to when I shall beavailable.

The exhibition itself, the first since the war,will contain a great variety of ingeniousworking appliances, model railways, modelaircraft, inventions, model boats, tools andmaterials. My old friend, Percival Marshall,is to be congratulated upon reinstituting thisnational exhibition so soon after the war.

German PatentsCONFERENCE to consider the questionof the future treatment of German -

owned patents in Allied countries took placein London recently. Delegates attended fromAustralia, Belgium, Canada, Czechoslovakia,Denmark, France, Luxembourg, Netherlands,Norway, Union of South Africa, UnitedKingdom, United States of America.

The chairman of the conference was SirHarold Saunders, the Comptroller of Patentsin the United Kingdom.

Patents taken out by Germans exist invarying numbers in all countries of theworld. Complete unanimity prevails amongthe Allied Nations that in no circumstancesshall any such patents within their territoriesrevert to the former German owners, and thequestion as to how such rights shall in futurebe disposed of presents many difficulties. Astrong sentiment prevails that it would beunfortunate if the continued existence of thesepatents should constitute an obstacle tointernational trade.

As a result of the discussions at theconference, the representatives of France, theNetherlands, the United Kingdom and theUnited States of America have signed an

accord which will have the effect of makingall patents of former German ownership nowcontrolled by their Governments, and inwhich there is no non -German ownershipnow controlled by their Governments, andin which there is no non -German interestexisting on August 1st, 1946, available withintheir respective territories to all nationals ofthe countries partly to the accord withoutpayment of royalties or without any require-ment to manufacture within the countrywhere the patents exist. The representativesof Australia, Canada, Czechoslovakia, andthe Union of South Africa have agreed torecommend to their respective Governmentsthat the accord should also be signed onbehalf of those Governments.

Representatives of Belgium, Denmark,Norway and Luxembourg feel that the specialdifficulties which exist in their countriesrender it necessary for their Governments togive a more detailed and closer examinationof the provisions of the accord before comingto a decision as to their policy.

As stated above the accord has been signedby four countries, and it remains open forsignature by other members of the UnitedNations and by neutral countries untilJanuary 1st, 1947. It will come into forceas soon as it has been signed by three furthercountries provided they sign before the end of1946.

International Contest for Power DrivenModel AircraftTHE Society of Model Aeronautical

Engineers recently held their annualContest for the Bowden International Trophy,at Heston Airport, London.

This contest was confined to machinesequipped with miniature internal combustionengines, and the rules had been drawn up tobring out the inherent flying qualities of themachines and to demonstrate the controlwhich the owners have over the machineswhilst in flight.

There were visiting entrants from Holland,France, Ireland and Belgium. Someinteresting machines with tiny enginesranging from r c.c. capacity (about the sizeof a thimble) to to c.c. (which is about aslarge as an egg cup), competed.

Machines driven by the new Auto Ignitionengines which are entirely devoid of theusual ignition equipment also took part andafforded an interesting comparison with theorthodox power plant.

Training for Electronic EngineersTHE rapid development in electronic

science and its new applications in thelast few years has created a great need for

BY THE EDITOR

technical training, and there is an urgentnecessity for such training to be provided inGreat Britain if we and our Empire are toretain our position in the forefront of thisnew industry. Such training will be requiredon a much wider and deeper scale than canbe handled by existing facilities. It mustprovide an effective combination of basictraining and practical experience.

This has been realised by E.M.I., Ltd.,who have embarked upon a courageouseducational enterprise. They were one of thepioneers of television, and other alliedelectronic applications. They developed theelectronic television system which amazedthe world and was adopted by the B.B.C.in 1936.

This company backed by its great resourceshas now decided to create an organisationwhich shall provide training over the wholesphere of the electronic sciences catering forthe needs of all types of students.

A new organisation known as E.M.I.Institutes, Ltd., has been formed, chargedwith the ambitious duties of providing schemesof training which shall become Empire wideand later world wide. The scheme is designedultimately to ensure for the Empire an amplesupply of scientific workers who will play theirpart in securing leadership for Britain in thisnew sphere of scientific development. Thenew institute will be governed by ProfessorH. F. Trewman, M.A.(Cantab), M.I.E.E.,M.I.Mech.E., whose qualifications are widelyknown. Prior to the war he was responsible forcontrolling the technical training of officersfor the various technical branches of thearmy. E.M.I. Institute as a first step haveacquired the London Radio College for theirnew headquarters. Those wishing to takeup training should write direct to E. M. I.,Ltd., Sheraton Works, Hayes, Middlesex.

Electrical and Chemical QueriesWILL readers please note that owing to

staff shortage we are unable to deal withelectrical and chemical queries. Whilst weare dealing with the subject of queries, maywe point out that we cannot undertake toprepare special designs, nor to answer querieswhich involve the preparation of illustratedarticles.

End of Volume XIIITHIS issue completes Volume XIII, and

readers are advised to obtain a copy ofthe index, which may be obtained for rod.,post paid, from the Publisher, GeorgeNewnes, Ltd., Tower House, SouthamptonStreet, Strand, London, W.C.2.

414 NEWNES PRACTICAL MECHANICS Sepiember, 1946 _

Aircraft Heating SystemsDetails of Components and Duct Installations

By BASIL JACKSON, A.R.Ae.S.

AN efficient heating and ventilatingsystem is a necessity for all modernaircraft. Due to the high altitudes

at which military and civil machines operate,both cockpit and passenger cabin air tempera-tures must be maintained within reasonablelimits. It is also necessary to install means ofheat control in aircraft which cruise atmoderate altitudes, because cabin air tem-peratures, in such cases, are also governed bylocal climatic conditions.

There are two main systems in use, viz :(r) Heating air by means of a water boiler.(2) Heating air directly by a muff -type

heat exchanger.Both systems make use of the engine

exhaust gases as a source of heat, but differin the method of application. Dealing withthe boiler system first, a diagrammaticarrangement of a typical layout is illustratedin Fig. 1. It will be seen that the maincomponents required are a water tank, boiler,and radiator. The boiler is constructedaround the engine exhaust manifold and is

Cold AirEnteringRadiator

Boiler

Pig. I.-Steam heating system.

connected by a pipe to the underside of thewater tank. The hot exhaust gases raise thetemperature of the water in the boiler andgenerate steam, which is passed to a smallradiator inside the aircraft. Cold air, drawnin by an intake fairing in the slipstream,flows through the radiator and condenses thesteam. The cold air picks up heat in theradiator and is passed into ducts, where itemerges at certain points in the cabin andcockpit. The water resulting from thesteam condensation is returned to the boiler.

The steam pipe from the boiler to theradiator is tapped by a pipe incorporating apressure regulator. This operates on thespring -loaded diaphragm principle, and main-tains a constant pressure in the system.When the pressure rises above the permittedmaximum, excess steam is ejected throughthe regulator outlet. Adjacent to the regulator,and from a union on the main steam pipe,is a safety valve. This is set to blow off at aslightly higher pressure than the normalworking pressure of the regulator and isinstalled in case the latter fails to operate.

Steam Shut -Off Coe,

Warmed Air"

Water TankThe water tank, if mounted some distance

from the boiler, may be manufactured fromaluminium (Fig. 2). The shell is made in threepieces : a main body constructed from sheetand welded along the seam, and two semi -spherical ends, beaten from flat sheet. Two

circular stiffening members are riveted insidethe extremities of the body before the endpieces are finally welded to it. The rivetsare din. in diameter, and pitched at approxi-mately sin., a soft aluminium washer beinginserted under each rivet to maintain awatertight joint.

A filler neck is welded to the upper end of thetank in such a position that the tank cannotbe completely filled. The lower end of theneck is flanged and shaped to the contourof the tank. A threaded sleeve, of aluminiumalloy, is riveted to the top of the neck, and tothis is screwed the filler cap.

The water pipe outlet connection at thetank base consists of an externally -threadedadaptor welded to the shell.

Mounting of TankThe tank is mounted on a cradle bolted to

the fireproof bulkhead in the engine nacelle(Fig. 3). The cradle is constructed fromaluminium alloy and has two straps of thesame material hinged at the outside edge.

See Detail "X"

Threaded RivetsAdaptor

Section v -v"Shell Removed

FillerCap

NeckeriDetail X

Fig. 2.-Construction of water tank.

These straps are located around the tankand bear on the shell adjacent to the twointernal stiffening members to prevent dis-tortion. A t t6in. thick strip of cork orfelt is cemented to the inside of each strap toreduce the risk of chafing due to vibration inflight. It will be seen that the two trunnionsin the cradle serve as anchorages for theturnbuckles at the extremities of the straps.

Boiler ConstructionThe boiler can either be constructed

integrally with the exhaust manifold or madeseparately and thus detachable for inspectionpurposes. An example of the former methodof manufacture is shown in Fig. 4: The out-side shell is of steel, similar in specificationto that used for the manifold, and is madeManifold Connection

To Radiator

Connection Reinforcing'To Tank Flange

Fig. 4.-Integral boiler construction.

S

,Cradle Bracket

Strap

Turnbuckle

Fiew On Arrow "X"

Fig. 5.-Mounting of tank.

from flat sheet bent to shape and weldedalong the longitudinal seam. The circularend plates are butt -welded to the main bodyand attached to the manifold by weldingaround the periphery of the hole. Areinforcing flange is then welded around thejoints.

The inlet connection from the water tankpipe comprises an adaptor with a steel flange,which is welded to the bottom of the boiler.

A detachable type of boiler is illustratedin Fig. 5. The circular end plates, in thisinstance, are not welded directly to theexhaust manifold, but attached to a steelsleeve. This is bolted to the manifold, thebolts assembling in slotted holes in the sleeveto allow for the expansion of the two manifoldsections when heated.

Detachable boilers are sometimes con-structed from brass, in which case the seamsand joints are brazed. Whatever the materialused, it is important that the boiler be sub-jected to a bench test before being installedon the aircraft. The usual practice is to fillthe boiler with compressed air at a specifiedpressure to ensure that 'the seams do notshow signs of failure.

RadiatorThis consists of a large number of .008in.

thick copper tubes approximately rein.long and with a common diameter of .25in.,positioned lengthwise between perforatedmetal frames (Fig. 6). The ends of the tubesarc sealed to the frames in such a manner thata space of .o5in. exists between the externalsurfaces of neighbouring tubes.

The tube array is then covered with a thinsteel or copper casing, which is attachedto the frames at each end. A steam pipeadaptor connection is riveted to the uppersurface of the casing at the forward end andanother, for carrying water, is similarlyattached on the lower surface at the aft end.

This type of radiator is a scaled downversion of the normal oil cooler used for aero-engine lubrication systems.

InstallationThe radiator is commonly mounted in the

cabin roof of twin -engine aircraft andsometimes on the fuselage side of single

Manifold

Sleeve Slotted Ho/e$Fig. 5.-Detachable boiler.

September, 1946

engine machines. The frames are carriedinside an aluminium fairing, the forwardsection of which forms an air intake in theslipstream. The frontal area of the intakeis approximately twice that of the radiator,and has a by-pass duct leading over the topof the radiator. A butterfly valve isincorporated in the by-pass, and is controllablefrom the pilot's cockpit. By this means, thepilot can vary the proportion of heated andcold air admitted to the cabin. This is inaddition to the steam shut off cock whichAir intake,

Radiator

Butterfly" Valve

Duct

Top SkinLine OfFuselage

Front View

Fig. 6.-Installation of radiator.

prevents steam from entering the radiator.Thus cooling air can be ventilated around thecabin as local weather conditions dictate.

The large diameter duct from the rearof the radiator is made from welded aluminiumsheet. It is carried along the cabin roof for ashort distance before branching off intosmaller ducts which lead to specific warmingstations in the aircraft. On military machinesthese stations include the astrodome, all gunturrets, navigator's and radio operator'scompartments, and the pilot's hand and footwarmer outlets. Sometimes a duct is usedto discharge heated air between a transparentpanel, attached to the windscreen structure,and the windscreen glass to prevent theformation of ice on the outside surface of thelatter.

As an alternative to aluminium, branchducts may be manufactured from plasticimpregnated laminated paper. This makesa very light duct possessing good heatinsulating characteristics.

Where maximum flexibility is required, asin the case of the pilot's hand warmer, thefixed duct is connected to one which can bemanoeuvred into various positions. Theseducts are approximately zin. diameter at theoutlet and are made from aluminium. Theyare built up on the domestic gas hose principle,the aluminium strip being flanged and spirallywound into pipe form.

In some heating installations the wholeof the cockpit is warmed by fitting extractorfairings in the skin plating of the nosefuselage. Fig. 7 shows a typical layout basedon this system. The main duct from theradiator is not branched forward, but emptieshot air into the centre portion of the fuselage.The heated air is then drawn forward into thecockpit, due to the pressure drop caused bycold air being withdrawn into the slipstream.

On large lairliners it is often necessary toprovide each passenger with an individual hotair control. This is accomplished by leadingthe main ducts along each side of the fuselage,between the outer skin plating and the cabinwall panels. Adjustable louvres in the wallpanels can be opened in intermediate stagesto suit personal requirements.

The steam and water pipes connecting theboiler to the radiator are of corrosion -resistingsteel, and are lagged with asbestos tape,lin. thick and sin. wide, to curtail heatlosses.

PrecautionsThe system is filled with distilled water.

If impure water, or even tap water, is used,the life of the boiler and the pipelines" is

NEWNES PRACTICAL MECHANICS

considerably reduced. Another importantpoint is that the complete installation has tobe drained if the aircraft is grounded infreezing weather conditions.

Muff -type Heat Exchanger SystemThis system differs from steam heating,

in that the temperature of the ingoing air israised directly by the engine exhaust.

It will be observed from Fig. 8 that coldair enters the pipe protruding forwardof the exhaust manifold and passes through amuff constructed around the latter. The coldair picks up heat from the exhaust gases

ExtractorFairings

Main Duct

Not Air Being Drawn Forward

Fig. 7.-Ducting system for multi-enginedaircraft.

NMWMMM

and in turn reduces the temperature of themanifold. This is an advantage, as theworking life of the manifold is therebyincreased.

Leaving the heat exchanger, the warmedair is conveyed in a duct to the valve chamber.

Branch Ducts Valve Chamber

Heat Exchanger Jacket Or Muff

Fig. 8.-MW-type heat exchanger system.

This consists of a flat -sided circular aluminiumbox with four outlets around the periphery.A central spindle carries a butterfly valvewhich is inter -connected, by a rod linkage,to a lever in the cockpit. The varioussettings of the valve are shown in Fig. 9.Duct " A " conveys cold air from an intakeunder the fuselage and ventilates the cabin.Duct " B " is a spill outlet for the hot airfrom the heat exchanger when only coolingair is required. Intermediate positions ofthe control lever vary the proportion of hotto cold air.

To Cockpit From Muff

Cn/d Air

Valve

Hof Air Luke Warm Air

Fig. 9.-Settings for valve chamber.

As a safety precaution, a relief valve islocated in the duct adjacent to the manifoldmuff. This is connected by wire controlto a small lever in the cockpit, and is operatedwhen the air admitted to the interior of theaircraft, even when diluted with cold air,becomes excessively hot. On some machinesthis valve is thermostatically controlled and

415

electrically connected to a warning lampon the dashboard.

The fairing over the external air intake isproduced from aluminium sheet and weldedto a stiff flange which is screwed to thefuselage skin. The large diameter duct fromthe muff to the valve chamber is of lightgauge steel, lagged with asbestos tape. Theremainder of the ducts in the fuselage aremade from aluminium, or laminated paper,similar to that used for steam heating systems.

The muff is manufactured from heat -resistant steel and is welded integrally withthe exhaust manifold. Muffs are sometimesbuilt with baffles riveted inside in order toguide the incoming air in a more precisemanner around the manifold to pick up agreater amount of heat.

The problems connected with the heatingof pressurised cabins are numerous. Theair, in this case, is heated after it leaves thecompressor, and the difficulty, at present, isthat of successfully humidifying large volumesof hot air. If this is not done efficiently,the heated air will be uncomfortably dry.

On aircraft powered by pure jet or turbinedriven propeller engines, the cabin may bewarmed by passing cold air into heat exchangerjackets around the jet efflux pipe.

Home -workshop Telephone :A Correction

In the article on A Home -workshopTelephone, which is published in our Augustissue, there is a slight error in the connectionsgiven in the wiring circuit, Fig. 6, on page395. The bell push is shown directly con-nected across the battery terminals. Oneof the leads to the battery should, of course,be broken to take the push, as indicated inthe accompanying diagram.

Telephoneand Bellin Atticor Shed

ThreeLines

Telephone andBell Batteryand Bell Pushin Kitchenof Scullery, etc,- -

Amended wiring circuit for home -workshoptelephone.

MASTERING MORSEBy the Editor of PRACTICAL WIRELESS

3rd EDIT! 0 N

This handbook, written with special regard for servicerequirements, will enable even the beginner rapidlyto become proficient in sending and receiving.

If -net

Of all Booksellers, or by post 112 fromGEORGE NEWNES, LTD. (Book Dept.),Tower House, Southampton Street,

London, W.C.2

Ifnet


Photo -electric CellsSome of their Applications for Industrial Purposes

By P. BOUSFIELD

IT is surprising how many ways there areof utilising photo -electric cells in scienceand industry. Some of these applications

will be dealt with in this brief survey of thesubject, and they are none the less interestingby reason of the diversity of their use.

As it would be rather pointless to describehere the complete circuit connected to thecell arrangement in an article concernedwith applications rather than design, let usassume that the reader has already familiarisedhimself with the general principle of electricalcircuits and just refer to the electrical operatingfactor as the " circuit."

Basically .the photo -electrical cell deviceis composed of the following :

(a) A source of light.(b) an intermediate space, and(c) a light sensitive cell,

and, of course-the operative " circuit."To understand the applications, we must

firstly refer in brief language to these threecomponents-one at a time in the sameorder as set out above.

(a) Source of LightThis we consider quite simply as an

ordinary electric bulb-just as we use in thehome ; but with an important proviso,which is that whereas domestic bulbs areof widely spaced wattage, the " light source "of our electric cell device may require tobe of a carefully calculated intensity accordingto the medium present in the intermediatespace (b), and the effect required upon the" light sensitive cell," (c)-which factorsare dealt with below.

While mentioning the light source we might,in passing, remember that the intensity oflight at a said object-as at (c)-is inversely

Liquid Electrolyte

IncidentLight Beam

An electrolytic photo -electric cell (verticalsection).

proportional to the distance of the objectfrom the source of light ; or, in plain language,if you go twice as far from the light it willbe half as strong, or intense. But variationsof (b) will affect this !

(b) The Intermediate SpaceIt is this space which provides all the

interesting variations, and from which proceedall the interesting applications of the photo-electric arrangement. The reader will readilyappreciate that if the light source is designedto influence the light sensitive cell at a distancefrom it, then the extent of the influence of thelight on its counterpart (c) will not be thesame if acting through ordinary air at (b)as it would if there were something at (b)which caused the light to be absorbed eitherpartly or entirely. Here, then, is the key tothe industrial usefulness of the device-and the scope of these mediums will be dealtwith as the final section of this article.

(c) The Light Sensitive CellThis can be referred to objectively as the

receiving end for the light for which it is thesensitive recipient and by which it is activatedin conjunction with the circuit. For thepurpose of this article it is sufficient tounderstand that the cell is sufficiently sensitivethat the slightest appreciable modificationin the intensity of the light as receivedcan be recorded by suitable apparatus; so

Evacuated Glass Bulb

GridLeads

Grid Terminals

Section through a selenium conductive photo-electric cell.

SeleniumCovered

Grid

Baseplate

let us now turn to the really interesting angleof this modern device which is its manifoldapplications.

General Applications of the SystemThe first application which comes to the

mind of the writer is that which was used atthe Science Museum in South Kensingtonsome years ago. Perhaps a number of readershave operated the device without knowing it !In this case the medium at (b) is the human beingpassing between the light source and the cell.In this way every person passing through aturnstile or barrier can be counted. Ofcourse, there must be an interval-if peoplewent through in a bunch this would onlyconstitute " one " medium ; but a turnstile(which actually may be a " self recorder "),spaces the people out and enables the cell toregister each person as " one " medium andrecord as such.

The system has a widely different applica-tion where it is applied for recording thefrequency of trains. In some of London'sunderground tube stations the train enteringthe station becomes a medium of lightinterference in the path of the photo -electriccell device there installed, and through themedium of the circuit and subsidiarymechanism the exact time of the " inter-ference " is suitably recorded and gives inter-esting statistics, e.g., the " rush hour " trainservice as compared with other times of theday.

Taking again a very different example-amongst many-we can study in brief howthe cell device can be usefully employed onboard ship. In some of the latest applicationsthe medium is sometimes " smoke " or even" oil," and whatever the use may be it isalways a question of a variation in the" medium " (b) which it has been stated canbe solid or liquid, provided that the com-ponents are designed to give the requiredamount of reaction according to which typeof " interference " of the light is underconsideration.

Applications Embodying Alarm SystemThe article would be prematurely concluded

if reference were not made also to the factthat in the " circuit " may be incorporatedan alarm system. The particular usefulness ofan alarm " device is that when conditionsare not as they should be, there will be anaudible reminder for, shall we say, thecaptain on the ship's bridge or the engineerin the engine -room, according to where theaudible alarm is caused to operate.

With an alarm bell in the circuit a warningof - shall we say - fire in the ship's holds canbe given when, for example, the smoke froma fire passes between the light source and thelight sensitive cell. What then happens isthat the smoke causes obscuration at themedium (b) and thereby makes or breaksthe circuit (according to which arrangementis used), and this activates the bell and givesthe required warning.

Concluding RemarksThe writer would like to add that when

the medium of interference is somethingonly semi -opaque, such as smoke or oil,

LightBeam

I

CellPhotoelectric

Amplif'erj1 -

100 -200v. H. 7: Loudspeaker

The photo -electric cell incorporated in thiscircuit is made to operate a loudspeaker.

then the light source must be of a moremathematically determined intensity and,generally speaking, the completely obscuringmediums are more easy to cater for thanthose which are either slightly or partiallyopaque.

TWO VEST-POCKET BOOKS !

WIRE AND WIREGAUGES

By F. J. CAMM3/6 or by post3;9

Obtainable from booksellers, cr(Book Dept.), Tower House,

NEWNES ENGINEER'SPOCKET BOOK

By F. J. CAMM10/6 or by post I I /-

by post from George Newnes, Ltd.Southampton Street, Strand, W. C. 2


The Victoria Falls Hydra -electric

Fig. 1.-Victoria Falls pcv.)er station. Thelower portion of the track is sem beside the

pipeline.

THE Victoria Falls and Transvaal PowerCompany completed in 1938 a verysuccessful hydro -electric scheme at

the Victoria Falls on the Zambesi River,and though this development is small incapacity, it is of particular interest since itis the first to be undertaken at the famousFalls and is completely automatic.

About 3o years ago a proposal for supplyingthe Rand with power from the Victoria Fallswas studied, the overhead transmission linewas to be 700 miles in length, and the pressure150,000 volts. Owing to technical difficultiesthis project could not be realised at thattime, but the Power Company retained itsright to develop the power at the Falls ifrequired at some future date, and the schemejust completed is the outcome of that arrange-ment.

The generating station is situated in thethird gorge, known as the " Silent Pool,"at a hairpin bend in the river about twomiles downstream from the Falls. It containstwo 1,000 kW. automatically controlled units,the purpose of which is to generate powerfor transmission over a distance of aboutseven miles to the town of Livingstone, untilrecently the capital of Northern Rhodesia,and also over a distance of about two milesto the Falls Hotel which, with the generatingstation itself, is in Southern Rhodesia.

Towards the end of 1936, a comprehensivecontract was placed with The English ElectricCompany for the power station and sub-station equipment to the arrangement andspecification of the London EngineeringDepartment of the Power Company, com-prising water turbines, generators, trans-formers, switchgear, cables, etc. On Marchi6th, 1938, the new power station wasopened by Sir Hubert Young, K.C.M.G.,D.S.O., Governor of Northern Rhodesia,who, by pressing a button, started up thefirst unit under automatic control, and LadyYoung afterwards switched in the supplyto Livingstone.

In addition to the two purposes mentionedabove, the plant will be able to supply anysmall industries which may spring up round

PlantDetails of this Important Under-

taking by The English Electric

Company on the Zambesi

River, in Southern. Rhodesia

of the Power Company, all these difficultieswere, however, overcome, and The EnglishElectric Company once . again demonstratedits capacity for the successful execution ofcomprehensive hydro -electric work in remoteplaces and under unpromising conditions.

Owing to the fact that the site is a famousbeauty spot, great care was taken by the

Fig. 2.-One of the 5,450 h.p. horizontal reaction water turbines and cylindrical balanced mainvalves (for the Victoria Falls plant) assembled at Rugby Works.

the town of Livingstone, and since NorthernRhodesia is a wealthy and rapidly developingColony, Livingstone may eventually becomethe centre of an active industrial area.

Several factors rendered the contract morethan usually difficult to carry out.

The power station site is very remote, allplant after conveyance by rail from Living-stone had to be unloaded into trucks on anarrow gauge railway and pushed by nativelabour some two miles to the top of the gorge.It was then lowered down a very steep gradientby a steam -operated hoist. The track, whichruns beside the 42in. diameter pipeline, isshown in Fig. 1.

The climatic conditions are damp andtropical and were exceptionally trying for theerecting staff, the engine -room temperatureat times reaching as much as to deg. F.Such conditions were also somewhat unfavour-able for the operation and maintenance of theinstruments, delicate relays and other appara-tus necessary for an unattended station.With the ready co-operation of Mr. N.Brooksbank, the Chief London Engineer

Power Company in South Africa to obviatedisfigurement, and this has been so successfulthat the power station and penstock arepractically hidden by vegetation from passers-by. Fig. 1 shows the unobtrusive nature ofthe building, which harmonises with itssurroundings.

As already mentioned, the station isdesigned to run automatically and is un-attended, the reason being that this type ofplant is economic and efficient, also thesituation of the station renders it unsuitablefrom the point of view of health for theprolonged attendance of operating staff.Consequently, a daily visit of inspection isall that is necessary.

The plant and equipment are of an interest-ing character, and a description of theirprincipal features now follows

Hydraulic EquipmentThe water is conveyed from the Zambesi

River to the settling tanks and forebay bymeans of a deep canal half a mile long.From the latter the water is drawn off through


screens and an isolating valve into a single42in. diameter pipeline and thence to branchpipes feeding the two turbines.

The turbines are of the horizontal -reactiontype, each has an output of 1,450 h.p. undera net head of 347ft., and runs at r,000 r.p.m.They are of the overhung type ; that is tosay, the turbine runner is mounted uponan extension of the generator shaft, thecomplete unit having only two bearings.

The turbine spiral casing is mounted uponan extension of the generator bedplate andthe combined unit is thus very rigid andcompact and characteristic of the company'shydro -electric design.

The turbine runner is made of solidstainless steel with polished streamlinedvanes, and is bolted to a forged flange on thegenerator shaft. The spiral casing is loga-rithmic in form and made of special cast ironstayed with high -tensile steel bolts locatedround the centre flanges. This methodof staying, though costly, is more satisfactory

which has been many times described invarious publications. It is in operation allover the world, and is completely reliableand satisfactory.

The governor actuator is mounted upon theservomotor, and the latter operates theturbine regulating ring. The servomotor isclosed by a strong spring, so that an ampleforce to close the turbine is available underall conditions ; the opening side is underoil pressure controlled by the actuator, thearea of the cylinder being sufficient to over-come the spring as well as the resistance ofthe turbine gates.

In accordance with the company's recom-mended practice, the actuator is gear -drivenfrom the turbine shaft, and a flexible steelblade couples the pendulum to the drivingshaft. This blade renders the system self -aligning.

The oil pressure for the governor is suppliedby a pump gear -driven from the main shaftand an alternative supply is given by a rotary

Fig. 3.-One of the 1,45o h.p. generating sets in the Victoria Falls power station.

in the case of high-pressure turbines thanstay vanes cast integral with the casing, sincethe latter occupy much space in the waterstream, and are liable to contain poor metaldue to cooling stresses.

Hydraulic end -thrust is minimised by theprovision of an exhaust pipe which conveysto the draught tube any leakage water passingthrough the gaps between casing and runner,thereby, preventing the building up ofpressure behind the runner crown.

Regulation is effected by well-balancedswivel gates connected by levers and linksto an outside regulating ring. The links aredesigned to break well before the elasticlimit of any major part is reached in theevent of an obstruction preventing one of thegates from following the regulating ring.

The links can be held in stock as inexpensivespare parts and are easily renewable in service.

Turbine DetailsThe overhung type of turbine is easily

dismantled and the runner and surroundingparts can be reached by simply removing thesuction bend. The bearing alignment is notdisturbed in the process and there is nonecessity at any time to remove the spiralcasing, which is therefore cast in one piecewith its bottom part embedded in concrete.

To obtain complete security and stabilityan amply dimensioned Michell thrust block isincorporated in the inboard generator bearing,and the bearing pedestal is tied by two strongstays to the turbine cover. Each turbine isprovided with an oil -pressure governingsystem of the company's standard design,

oil pump incorporated in the governor baseand driven by a small water turbine of theimpulse type. There is no need in the presentcase for an oil -pressure receiver or reservoir,since only the comparatively slow opening ofthe servomotor is accomplished by oilpressure, closure being effected by a spring,whilst the pump is capable of supplying allthe oil required ; this is a distinct simpli-fication.

The turbine inlet valves are of the com-pany's cylindrical balanced streamline typeand due to their reliability are particularlywell suited to an automatic station. Thesevalves have also been many times described,and it is only necessary to say here that thedesign ensures safe closure under emergencyconditions without water hammer, and alsobalance and control by comparatively smallforces practically independent of the actualdischarge through the valve.

While the valve is hydraulically operatedit can be electrically controlled from theswitchboard either to open or close.

On the upstream side of the cylindricalbalanced control valve a hand -operated sluicevalve is provided, so that each unit can becompletely and independently isolated fromthe pipeline when required.

Fig. 2 shows the turbine assembled withinlet piping and main control valve at RugbyWorks, whilst Figs. 3 and 4 show the com-plete units on site. In the left foreground ofFigs. 3 and 4 can be seen the turbine -drivenoil pumping set for supplying oil to bothgovernor and bearings, in the centre is thegovernor servomotor surmounted by the

actuator, and in the right foreground arethe duplex oil and water strainers. Throughthe latter passes the water for cooling thebearings and for cooling the air in the closed-circuit ventilating system of the generator.

GeneratorsEach of the two generators has an output of

,000 kW., 5,25o kVA. at o.8 power factor,3,300 volts, 5o cycles, and runs at r,000 r.p.m.All rotating parts are designed safely towithstand an overspeed of 1,85o r.p.m.

The generators are of the horizontalsalient -pole type fitted with two pedestalbearings on bedplate and with shaft extensionto carry the turbine runner.

The stator frame is built-up of steelelements welded to form a rigid and strongframe. The steel wrapper plate is weldedto -the outer edges of the frame and formsan efficient chamber for conveying the air tothe bottom chimney. The stator windingis of the basket type in open slots with twocoil sides per slot, the whole winding beingsuitably braced to withstand stresses set upon short circuit. The ends of the machineare enclosed by segmented sheet -iron shields.

The rotor body consists of a high-gradesteel forging in one piece with the shaft, anddovetail slots are machined in the peripheryof the forging for retaining the poles andwinding. The poles consist of steel lamina-tions riveted between cast -steel endplates.

The field winding consists of copper stripwound on edge on a metal spool from whichit is insulated by a mica lining. Fanscomprising duralumin blades are providedat both ends of the rotor.

A flywheel consisting of rolled-steel platesis mounted upon the shaft at the slipringend of the machine between the rotor bodyand the bearing, and this, taken in conjunctionwith the rotor, provides an ample flywheeleffect to fulfil the speed regulation guarantees.The inertia thus provided also allows aturbine relief valve to be dispensed with underthe hydraulic conditions prevailing in thepresent case. The shaft is extended beyondthe bearing to take an overhung -type exciter.

The pedestal bearings are ring -lubricatedand, as already stated, the driving -endpedestal has incorporated in it a Michell typedouble -thrust bearing.

Both thrust and journal bearings are fedwith oil from the turbine governing system,and a thermostat is provided in each to makecontact at a predetermined temperature toshut down the set.

Ventilation is on the closed-circuit principle,the cooled air being drawn into the machinefrom an intake in the alternator pit, by therotor fans, through fan shields bolted on tothe end covers. The air is distributedthrough the machine to the bottom chimney,whiCh is centrally situated between the fanshield openings. A short length of trunkingconnects the bottom chimney to the cooler,which stands on one side of the machine andis readily accessible to the station crane.

SwitchgearThe power is transmitted from the

generating station to the Falls Hotel at3,300 volts, which is the generating voltage,and to Livingstone by means of a 22,000 -volttransmission line.

The whole of the switchgear, transformersand connections for the power station and thetwo substations at Falls Hotel and Livingstoneformed part of the company's contract, andthis equipment included the automatic controlgear.

The 3,300 -volt power station switchgearis of the built-up sheet -steel truck andcubicle type, totally enclosed and vermin -proof and arranged for floor mounting. Thepillars are of the company's standard designand the oil circuit breakers have a rupturingcapacity of 50,000 kVA. Generator and


feeder pillars are provided together with ametering cubicle and Merz-Price gear for thegenerator neutrals.

The control board consists of blackenamelled slate panels and includes theautomatic control panels, the generatorcontrol panels, and the exciter and automaticvoltage regulator panels.

Other power station gear and equipmentinclude the generator neutral earthing equip-ment, field suppression switch pedestals,station battery with control panel, tricklecharger and motor -generator set, and 220 -voltfloor -mounting combination fuse -switchboard.

Automatic ControlThe two generating units in the power

station run unattended, the engineer in chargehaving his hiring quarters some six milesaway.

For the present only one unit will be runat a time, but in future, when the loadincreases and further units are installed,automatic synchronising will be required, andthe present control gear is so designed thatthis feature can be added with the minimumof disturbance.

Tests for automatic changeover from oneunit to the other showed that only 21 minutesis required to regain continuity of supplyif one unit should fail.

The starting impulse is given by a pushbutton on the control panel in the powerstation, and thereafter the running up of theturbine and the going into service of thegenerating unit is entirely automatic.

The sequence of operations is as follows(x) On the starting impulse being given, a

master contactor closes.(2) The closing of the master contactor

causes the main valve to open slightly,allowing pressure to build up in the turbinespiral casing.

(3) The building up of normal workingpressure in the spiral casing enables apressure device to cause the main valve tobe opened fully.

(4) When water is admitted to the spiralcasing it is also admitted to the pump turbineand to the oil and air coolers. The pumpturbine runs up and provides pressure oilfor the governor and bearings.

(5) Oil pressure being available, thegovernor takes limited control and startsgradually to open the turbine gates.

(6) The turbine begins to rotate and as aconsequence :-

(a) The gear -driven oil pump starts tobuild up pressure.

(b) The field starts to build up, causingthe voltage regulator to commencebringing the voltage to normal.

(7) The occurrence of oil pressure in thegear pump causes the turbine -driven pumpto shut down.

(8) When the speed approaches normalthe governor takes full control and thealternator voltage approaches normal.

(9) By means of a time -delay relay a steadycondition is attained, whereupon the solenoidof the main oil circuit breaker is energised,the circuit breaker is closed, and the startis then complete.For shutting down :-

(x) The master -contactor is de -energisedand this cuts off the protective circuits andcloses the governor by means of its oil valvesolenoid.

(2) At the same time the main valve closingcontactor is energised, causing the valve toclose by means of its motor.

(3) As the governor closes, the turbinegates reach the no-load position and the mainoil circuit breaker is tripped.

(4) When the main valve is fully closed alimit switch cuts off the valve motor and atthe same time the oil -pump turbine comesto rest.

Protective DevicesAutomatic protection is given against any

of the following :-Sustained over -current.Over -voltage.Over -speed.Alternator field failure.Internal faults.Overheated bearings.Oil failure.Exceeding of normal starting time.

Fig 4. - The

Substation EquipmentAt Livingstone the incoming 22 kV. supply

is transformed down to 2,200 volts by meansof two 75o kVA. 3 -phase oil -immersedself -cooled indoor type transformers providedwith on -load tap -changing equipment.

The 2,200 -volt switchgear is of the truckand sheet -steel cubicle type comprisingtransformer and feeder pillars, meteringequipment, and tap -change control cubicle.The equipment at the Falls Hotel substation

wo generating sets, viewed from

Any of the aforementioned would cause theunit to shut down and the main oil switchto trip.

In the event of the running machineshutting down, the other machine willautomatically come into operation.

When any further units are installed, thenext machine will run up when the runningmachine approaches full load. This sequencewill repeat as necessary until all availableplant is running.

he turbine ends.

comprises a 3,300 -volt truck -type switchboardfor two 200 kVA. transformersof a similar type to those installed atLivingstone, and a tap -changing controlcubicle is also provided.

For local distribution there is a combinationfuse -switchboard for the 400;'230 volts,3 -phase system.

(By the courtesy of The English ElectricCompany, Ltd.)

Civil Aviation NotesFerrying Vehicles by Air

ONE of the most attractive arguments infavour of transporting motor vehicles

by air is that, in computing costs for thismethod of carriage, material and man-hourcharges for crating may be ruled out. Takenin conjunction with the unrivalled speed andflexibility of air transport, this fact makes " airferrying " of vehicles a sound commercialproposition.

There is to -day no aircraft in the worldmore suitable for vehicle -ferrying than theBristol Freighter. Its roomy interior, towhich wide nose doors give unobstructedaccess, makes the loading and unloading ofcars an extremely simple operation. Withthe doors fully open, the car can be drivenup a low ramp-the door sill is only 4ft. 6in.from the ground-and then secured inplace by means of the ample tying -downpoints provided. Some indication of thespace available in the Freighter is givenby the fact that 7ft. 6in. headroom is providedthroughout most of the hold, while the widthbetween the sides is 8ft.

Another particularly cogent argument forthe use of the Freighter on work of this kindis the great economy of its operation and itsability to land almost anywhere, being ableto take off and land within a comparativelyshort distance on unprepared ground. With a

specially strengthened strip on either sideof the floor of the hold to take vehicles with awheel load of up to 5,00olb., the Freighter isthe first choice for this specialised transportpurpose.Gas Turbines to Power Air -liner

THE Theseut the first Bristol gas turbineunit to be produced, may well be the

first Bristol turbine to be fitted to a civilaircraft. It has been stated by Sir FrederickHandley Page that the third version of theHermes air-Iiner will be powered by fourBristol Theseus gas turbine engines ;supplanting the four Bristol Hercules enginesof the earlier versions of the Hermes.

The first gas turbine airscrew unit in theworld, the Theseus combines airscrew andjet, about 8o per cent. of the power outputbeing taken to drive the airscrew and theresidue being utilised in the form of a jet.The third version of the Hermes will have afuselage x3ft. longer than the first and willcarry 64 passengers, as compared with amaximum of 5o passengers for the Hermes I.Installation of Theseus engines will raise thecruising speed of the aircraft to 335 m.p.h.,equal to the maximum speed of the Hercules -powered version. All three types will havepressure cabins and will be air-conditioned,enabling them to fly in the sub -stratosphereand " get above the weather."


C -stoff

The only rocket powered interceptor to see service during the war, the Messerschmitt 163B0was fitted with an HWK 109-509A1 Walter engine. This photograph shows the landingskid and tail -wheel fully extended. The main wheels, attached to the skid, were jettisoned

once the machine was airborne.

appreciably higher order of conductivity. Alloutward directed pressure was absorbed bythe outer shell, which could be of heavierconstruction as it was not subject to extremesof temperature. This explains the reason whyno particularly high-grade steels were used inmany of Germany's most efficient rocketmotors, including the V-2, when motorsemploying highly durable materials in theirconstruction but not regenerative operating,were disrupted after merely a few seconds'firing.

Since the time of Singer's early experi-

/n)cctor Disc

C-stoff

Rocket PropulsionThe HWK 109-509 Walter

EnginesBy K. W. GATLAND

(Continued from page 388, August issue)

THE design of the Walter aircraft engineswas regenerative ; that is to say, thefuel component of the liquid propellant

was circulated prior to its injection forburning through a cooling jacket encompassingthe combustion chamber and nozzle. In thisarrangement the fuel acts to cool the motor,and, conversely, to vaporise the fuel bypre -heating, with the result that there is amarked gain in the thermal efficiency.

Another important factor of regenerativedesign is that the inner wall of the combustionchamber can be quite thin and yet withstandfull combustion stresses.

One of the first experimenters to employthis system was the German, Dr. EugenSanger, who first demonstrated his fuel -cooled rocket motor in 1931. This unit hasbeen fully described in an earlier article(PRACTICAL MECHANICS, March, 1945, p. 200),and it will be recalled that the one essentialrequirement was a high pressure fuel -feedsystem, and that Sanger achieved his verysuccessful results in the use of a Bosch dieselpump which permitted pressures within thejacket of 450 to 2,200 lb./sq. in. As the fuel -feed pressure must necessarily be greater thanthat resulting from combustion, the stressdirected on the firing wall of the chamberacted toward the axis of the motor. Thus, theinner wall was of a much thinner section thancould otherwise be employed, and of an

C - staff

T- stoff

Steam

SteamPre -heating Pipe

C-stoff

C-stoff

SteamPre -heating Pipe

Layout Of Injectors,C - stoff 8. Steam Inlets

ments, a number of other motors employingthe same principle had been developed, manyof which were featured in tests carried out bythe American Rocket Society.

It was, in fact, Nathan Carver, a memberof this group, who provided a further im-portant contribution toward solving theproblem of motor burn -out, which whencombined with Sanger's scheme made thepossibility of efficient liquid rocket enginesa certainty.

This was, of course, the " concentric -feed "principle which Carver first demonstrated

Port iy

Starboard

To Auxiliary PressureBalancer

(Not Shewn)

ONon -return& Pressure

Reducing Valve

Turbine Waste

0 CD

StartingValve

Spill Line From Main PressureBalancer And Riding Valve

To

AuxiliaryFeed

PressureBalancer

(Not Shewn)

To TurbineWaste

Fig. 76.-Diagrammatic layout of the HWK 109-5090-main system. The cruising motor has been omitted for clarity.

A. T-stoff inlet from tanks. J. Starting reservoir. R.B. C-stoff inlet from tanks. K. Control valve. S.C. T-stoff pump. I.. T-stoff to turbine. T.D. C-stoff pump. M. Scavenge pipe. U.E. Turbine. N. Stage one. V.F. Steam exhaust from turbine. 0. Stage two. W.G. Distributor. (Main pressure balancer.) P. Stage three. X.H. Steam producer. Q. Scavenge valve. Y.

Filter.C-stoff inlet to jacket.Combustion chamber.Supports for auxiliary motor.Turbine control valve.T-stoff feed lines.C-stoff feed lines.Pilot's control lever.

NOTE ; All notation in the text refer to this figure.

September, 1946

during the small-scale rocket aeroplane trialsat Greenwood Lake, N.Y. in 1936 (PRACTICALMECHANICS, February, 1945, p. 158) andwhich was later taken up with even greatersuccess by other technicians of his Society,principally, R. C. Truax and J. H. Wyld.His associates, in fact, produced severalconcentric -feed regenerative types which inconception were essentially nothing less thansmall-scale versions of the power unit ofthe V -a.

As the result of similar and more intensified

Fig. 77.-Sectional diagram of the HWK 1o9-5o9C combustion chamber.

Combustion chamber.Nozzle throat.Nozzle mouth.Injector.Orifice for C-stoff entry into injectors.Inner shell of combustion chamber.Outer shell of combustion chamber.Concentric -flow section.Helical vanes on concentric -flow

section.

Helical vanes on Inner shell.Outer shell over nozzle.Coolant inlet.Supports for auxiliary motor.T-stoff inlets.C-stoff inlets.Injector disc.Drain pipe.Coolant outlet.

research which was proceeding under militarysupervision in Germany, the prototype engineof the A4 long-range rocket appeared, andwith it the motors of the Messerschmitt 163series.

The HWK 109-509 Walter UnitsThe HWK ion -509 engines (the HWK

109-509C main system is shown in Fig. 76)comprised two main sub -assemblies : (a) therocket motor, and (b) its turbine -drivenpumps, accessories and controls, separatedby approximately 4ft. of feed lines, these beingcompletely encased by a metal conduit whichtransmitted the thrust. In the case of the109-509A1 unit, the total weight (lesspropellant) was only 8141b., while the amountof T-stoff and C-stoff necessary to operate theMesserschmitt 163B0 during its four minutesperiod of powered flight was 3,4181b. and5,03i1b. respectively.

The combustion chamber (Fig. 77) wasconstructed of rough forged carbon steel,being of cylindrical section rounded at thehead and flowing into a convergent -divergentexpansion nozzle. Its length was approximatelyIlan., the internal diameter 9.Soin., thevolume 825 cu. in., and the throat area ofthe nozzle 5.15 sq. in.

The inner walls were only On. in thickness,yet able to withstand temperatures of nearly2,000 deg. C. and pressures approaching24 atmospheres. An K in. average gapseparated the inner and outer walls of themotor through which the C-stoff coolantflowed.

Of rolled carbon steel construction, theouter shell of the motor was seam -welded,the nozzle being joined to the chamberportion at the mouth. A 6.5oin. diameterdisc, on which were mounted the injectorvalves for the propellant, was also welded-at the head of the chamber.


Situated in the space between the innerand outer shells of the nozzle was a con-centric flow section, ensuring a rapid andeven flow of coolant around that mostvulnerable portion of the motor. This wasan aluminium alloy casting and embodiedthree helical vanes situated to coincide withthe convergent section of the nozzle, intendedto swirl the C-stoff evenly around the linerin its path to the fuel injectors. A furtherset of five vanes was attached to the outersurface of the liner at the divergent section.

The propellantQpo entered for combus-

tion at the chamberhead, passingthrough twelvepressure actuatedvalves mounted onthe disc plate. Thelatter was machinedfrom carbon steelbar, while theseparate injectors,which screwed intothe plate, were ofstainless steel.

Operation of theMotorThe oxydiser

passed down thecentre of each valve,but upon entering

© the chamber, wasdeflected outwardsfrom the axis bymeans of a cone.

This cone wasobviously the crucialpart of the injector,and being springloaded, not onlyprevented blow -backs but also actedas a regulator.

It will be seen from the figure that thesupply of fuel to the motor was through amain distributor (G), and that a pipe firstbrought the C-stoff to the coolant jacket.The fuel solution, having circulated aroundthe motor, was then filtered and deliveredback to the distributor, passing through acontrol valve where its pressure was regulatedprior to being fed forcombustion. All of thepipes, to and from themotor, passed inside themetal thrust conduit,the fuel pipes branchingout into subsidiary feedsjust before reaching thehead of the combustionchamber. These, ofcourse, fed into thetwelve injectors.

Apart from flowingthrough a filter andcontrol valve in thedistributor, the T-stofffed directly from thepump into the chamber.There were seven inletsand these led into a cavityinside the injector plate, Fig. 78.-Diagramthe fuel passing again in the HWKthrough filters and theninto the injectors via an annular orificesurrounding the deflector cone, finally enteringthe chamber and mixing with the oxydiser.Combustion took place spontaneously atthe deflector cones, each injector providingits own " concentric -feed."

The T-stoff underwent vigorous decom-position, liberating nascent oxygen, whichwas burnt with the alcohol as the main sourceof heat. Actually, the violent reduction ofthe peroxide, under heat and catalytic action,also released mass in the form of superheated

Control Valve8, PressureEqualiser

MainC-stoffLine -----

ThrustWeb --

TurbinePumps

Steam Exhaust

421

steam, adding materially to the weight ofthe exhaust.

In order to overcome the possibility ofexplosions when the motor was expended ofpropellant, it was necessary to drain anyC-stoff that remained from the coolant jacket.This was catered for by a pipe which passedfrom the jacket at a point beneath the chamberto a valve (Q). All the while the turbine -drive of the pumps operated, this valvewas closed, but when the pumps ceased tofunction and pressure fell off, the valve wasallowed to open and the remaining fluid inthe jacket passed out through the scavengepipe (M)

StartingThe starting procedure consisted first in

working the pumps, but this did not entailreleasing propellant to the combustionchamber with its voracious consumption ofapproximately t,000lb. per minute. Thepilot initiated the turbine drive by movingthe lever of his control quadrant to Idling,"energising the starter motor and opening thetank flow -docks. This electric starter, whichwas geared direct to the turbine shaft, drovethe pumps at low power, causing the feed -linesto fill with propellant. The pressure, however,was not sufficient to overcome the valvesetting in the main T-stoff line to the steamproducer, which activated the turbine.

In units which were not fitted with electricstarters, there was an auxiliary startingreservoir which contained sufficient T-stoffto operate the turbine for six seconds, therebyallowing tune for peroxide from the mainsupply to reach the steam generator. A by-pass line fed back a small quantity of peroxideinto the steam generator (H), and the turbinequickly developed sufficient power in thepumps to operate the normal feed to thesteam producer. The bypass then automatic-

cut out.This procedure was necessary each time the

motor was re -started after the aircraft hasbeen gliding with power off.

The Steam GeneratorThe steam generator comprised a porcelain -

lined pressure vessel with a wire cage fittedinside in which were distributed a number ofporous pellets impregnated with calciumpermanganate and potassium chromate. From

StartingReservoir

Coo/ant \Filter \

\

EngineSupport

Ejector

SteamProducer

Starting Valve

ThrustConduit

Coolant Pipes

MainMotor

Auxiliary ScavenoeCruising Motor Pipes.

showing the layout of the main components1o9 -509C Walter bi-fuel rocket engine.

the reservoir, the T-stoff fed by gravity intothe generator, where, upon meeting thecatalyst, there resulted a violent decompositioninto super -heated steam and gaseous oxygen.Actually, the peroxide was sprayed on thecatalyst from the top of the generator, and thecage itself rested on a perforated sheet ofmetal near the floor of the container. Alarge pipe conveyed the steam from the baseto the nozzles of the turbine, and afteroperating the rotor, the waste gases werevented to atmosphere.


In the developed engine HWK 109-509C,two small pressure lines ran from the mainsteam pipe to convey pressure to the ejectorvalves (K and L), which were provided forthe purpose of extracting air from the pumpswhen the power has been cut for any reason.This was, of course, a safety measure toprevent airlocks and to afford protectionfrom explosions which might otherwise haveoccurred. The steam used here was eventuallyexhausted into the combustion chamber, beingalso used to pre -heat the fuel during startingoperations.The Turbine -pump

In order to maintain pressures of the orderof 350-3601b./sq. in. in the feed lines andmotor jacket, it was obvious that the solutiondid not lie in the use of gas -operated pressun...chargers. The difficulties confronting thedesigner of a mechanical driven pump wereenormous, and had it not been found possibleto use concentrated hydrogen peroxide as thesteam producer, it is doubtful whether eitherthe rocket fighters or the V-2 would haveperformed anything like as well as they did,for reciprocating engines and the extra fuelentailed meant so much more unwanted weight.

The pumps of the HWK 109-509 werecalled upon to supply over zo lb. of pro-pellant for every second the motor wasoperating under conditions of maximum thrustand at a pressure sufficient to maintain a com-bustion chamber pressure of over 35o1b. /sq. in.

The turbine group comprised a single -stage turbine with two centrifugal impellersmounted on a common shaft at either side.

Machined from chrome steel, the Loin.diameter turbine rotor was housed within analuminium alloy casting. The T-stoff impellerwas manufactured from 13 per cent. chromesteel, while the materials of the fuel impellerwere not so critical so long as copper wasavoided in the alloy. It was, however,usual to employ aluminium or aluminiumalloy, although chrome steels with an optimumpercentage of 18 to 21 chromium was apossible alternative. Their housings werealso of chrome steel.

For the remainder of the feed system, thehydrogen peroxide lines were of aluminiumalloy, though, of course, not containing copper,while the fuel solution was carried by pipesof mild steel.From " Idling " to " Power "

Immediately sufficient pressure wasregistered on an indicator in the cockpit,the pilot moved his throttle lever into thefirst gate. This caused the propellant tofeed through three of the injectors (N).The second power phase brought intooperation three additional injectors, whilethe third and final setting functioned theremaining six.

In the case of the improved HWK 509-509motors, there was in addition to the mainrocket motor a cruising chamber, the completelayout of which is shown in Fig. 78. Theauxiliary chamber, which was supportedbeneath, was also regenerative, but had onlythree injectors. It operated at a fixed power,the 109-509C version developing fully 88o1b.thrust.

For climb, both chambers were operated toobtain maximum power, but for cruising, themain motor could be cut out, the use of theauxiliary chamber providing a better solutionthan simply throttling back on the mainsystem. This enabled a given thrust in thelower power setting to be taken over by thesmaller chamber, with the result that efficiencywas much improved and a lower propellantconsumption obtained.

Performance -DataIn the combustion chamber, the chemical

energy of the propellant was converted toheat energy, 1,430 C.H.U. being theoreticallyavailable for each pound consumed. Themaximum thrust resulting from the mainchamber was 4,400lb." with a combustionpressure of 3531b./sq. in. and a chambertemperature of 1,950 deg. C.

With the thrust averaging 3,7oolb., however,the temperature was reduced to between1,750 and 1,90o deg. C. The propellant ratiowas then between 3.7 and 3.3 to one.

The thermal efficiency was found to be inthe region of 28 per cent. at maximum thrust,falling to something less than to per cent. atthe maximum setting. This poor value ofefficiency was, of course, favourably offsetby the inclusion of the cruising chamber innewer designs. The reason for this is obviousin that the smaller throat area and chambervolume permitted higher pressures than wouldhave been possible in the larger motor withthe same number of injectors in use.

(To be continued.)

Items oExhibition of Non -utility Furniture

EXPERTS met in London on April 25thto look at some 1,000 designs for

non -utility furniture submitted forinclusion in the Government -sponsored" Britain Can Make It " Exhibition, whichopens this month at the Victoria and AlbertMuseum.

Permits will be issued for the timberrequired for constructing the selected designs,and from this range of furniture the finalselection for the exhibition will be made.

New furniture will be an important featureof the exhibition-displayed in furnishedrooms and in nurseries, gardens, offices, andrestaurants.

Since there will be complete freedom inthe choice of materials for the furnitureexhibits, British manufacturers will have theopportunity of showing that the restrictionsof the war years have not affected theirleadership in design and craftsmanship. Itis anticipated that some of the furnitureselected will be based on the wartime advancesin new techniques and new materials.

The large number of entries for thissection is evidence of the keen interestdisplayed by British manufacturers in the" Britain Can Make It " Exhibition. It isalso a remarkable tribute to the resiliencywith which British furniture manufacturersare facing problems of reconstruction.

Non -utility post-war developments in allkinds of consumer goods will be shown atthe exhibition, which is being organised bythe Council of Industrial Design and financed

Interestby the Government. No space is being sold,for all exhibits are to be carefully selected toillustrate the best in British industrial design.Selections for other sections of the exhibitionwill be made later in the summer.

The exhibits are to be chosen' by expertsdrawn from a panel of selectors under thechairmanship of Lord Woolton.

The AudiometerTHE audiometer was first used to recordA sound in 1910. Since then it has

recorded traffic, Dame Nellie Melba, H.M.the King, Chamberlain, Churchill, gunfire,Hitler's voice and most imaginable sounds.It operates by direct recording, unlike the" talkie." Used in study of UndergroundRailway noises and for the silencing testson Imperial Airways. This instrumentmade the first known records of London'straffic long before era of talking pictures.(See illustration below.)

Comfort for Air TransportTO add to the comfort of passengers -

travelling in an aircraft means have beendevised to minimise transmission of, soundand other vibrations to the interior of thecabin and other compartments of an aero-plane.

A further object is an improved methodof regulating the temperature of the cabin.

The invention comprises an aircraft com-partment in which an inner cell or chamberis suspended through the medium of resilientvibration-damping members attached to

members of the .outer frame. The arrange-ment is such that except at the points of itssuspension, the inner cell compartment isentirely surrounded by an airspace sealedfrom the outer atmosphere.

The transmission of sound and othervibrations depends to a large extent uponthe existence of rigid physical connections.And, in order to prevent or at least minimisesuch transmission, it is important that thesmallest practical number of suspensionmountings be employed. Then the conductingefficiency of such physical connections asare essential can be reduced by incorporatingresilient damping means at the minimumcost of added weight.

The device provides also for circulatingthrough the aforementioned surroundingair space of the compartment a current ofair or gases in such a manner that it flowsover the outer surfaces of the inner cabin.The temperature is regulated above or belowthe atmospheric temperature which it isdesired to maintain in the cabin.

Portable Fire AlarmWHEN people retire to bed at night the

remains of fuel in the grate are some-times left burning. In these circumstancessparks from the grate are a not uncommoncause of a fire.

To guard against such a contingency,there has been devised a portable fire alarmwhich can be placed on the hearthrug. Incase of fire, this automatically sounds analarm of sufficient duration to awaken theoccupants of the house.

As no electrical connections have to bemade, the device is readily portable, and canbe carried from one room to another and usedwhere it is most required.

?,ha.pkti,!

Sound wave photograph of an atomic bomb explosion. Taken on the audiometer by Prof. A. M. Low. This is a visual record of the greatestunderwater explosion ever known.

September- 1946 NEWNES PRACTICAL MECHANICS 423

The Story of Radar-Centimetric Research Surface Warning

Development : Shore Stations(Concluded from page 362 7uly issue)

ASERIES of modifications giving in-creased power, accuracy and reliabilitybrought the three original gunnery

sets to a high state of efficiency. Theirgreat day came when the modernised ver-sion of the set which had shadowed theBismarck, sent the terrible salvos of the Dukeof York's great guns tearing into theScharnhorst.

Centimetric Research-The New Mag-netron

The scientific effort which made possiblethe gunnery sets, had concentrated on trans-mitting and receiving technique on theshortest decimetric wavelengths consideredpracticable with the valves available at thattime. Although this was adjudged the mostuseful line of investigation in 1938, it wasrealised that still shorter waves in the centi-metric band would have important appli-cations if a type of valve giving sufficientpower could be produced. Success stillseemed a long way off in the summer of1940, but by November two developments invalve research had led to striking resultswhich were being demonstrated by the AirMinistry Research Establishment at Swanagein surface detection trials against the targetof a submarine. These developments werethe greatly improved performance obtainedby inter -Service and industriallaboratory teams from the " strapped "magnetron and the production at H.M.Signal School's Bristol laboratories of a newtype of velocity modulated valve to providethe centimetric local oscillation frequencyrequired for the receiver.

A new centimetric team was hurriedlyformed at the Admiralty Signal Establishmentinto which the experimental section of H.M.Signal School had now grown, and went toSwanage for six weeks' liaison work. Theyreturned to Eastney with an improved ver-sion of the Swanage apparatus and set towork to produce a centimetric surface warn-ing set which could be fitted in a ship assmall as a corvette.

The Answer to the U-boatThe defeat of the U-boat to secure our

supply life -line had by now become oneof the most urgent problems of the war.Asdic detection badly needed support inlocating surfaced U-boats and centimetric" R.D.F." looked like supplying the answer.

The essence of centimetric developmentwas to provide detection of the smallest poss-ible target to the limit of the horizontalbeam produced, i.e., up to the horizon. Justas a bigger bulb or a further concentration ofthe beam is required to extend the range ofa motor -car headlamp, so either the powerof the pulsed transmissions must be increasedor the beam more concentrated to increasethe range of detection of a Radar set. Nofurther increase of power from the magnetronwas possible at the time. Efforts had there-fore to be devoted to concentrating the beam.This, in the case of surface warning sets, maybe regarded as shaped like a cigar. Nar-rowing this in the horizontal plane increasedits concentration and improved bearingaccuracy, but the beam must be allowed ade-quate vertical depth or it would be impossibleto prevent it from rolling off the targetwith the motion of the ship, a motion whichwas likely to be extremely violent both in

quality and quantityin corvettes a n dother small ships.

The very highfrequencies of thecentimetric w a v e -b a n d presentedpeculiar difficultiesdue to the losseswhich occurred infeeder connections.Even with the spe-cial types of feedercable by then avail-able, the lengths usedhad to be severelyrestricted. T hi snecessitated t h emounting of part ofthe actual trans-mitter and receiverimmediately behindthe aerials, the wholehaving to be pro-tected from t h eweather by a smallhut somewhat like alighthouse lanternwith windows madeof Perspex.

Type 271 Goes toSea-Periscope

Detection

The Radar officer climbs the mast to inspect the aerial on the S.S." Canterbury," which now makes the trip between Dover and Calais

in connection with the " Golden Arrow " service.

Early in March, 1941, a prototype set wasinstalled in the Flower Class corvette, H.M.S.Orchis. Once again predictions were amplyjustified, even so small a target as a sub-marine's periscope being detected at a usefulrange. The time had tome to take chancesagain. Components for some 15o sets wereordered, increasing to 350, in May. By theend of July 25 ships were fitted or beingfitted. So urgent was the requirement forthis set, which was given the title Type271, that i2 models were actually madeat Eastney by Admiralty Signal EstablishmentStaff. Type 286 cathode-ray tube displayunits were gutted and rebuilt for the Type271, one hundred of these being convertedat the Eastney laboratory whose staff madeup for lack of mass production experiencewith keenness and enthusiasm.

Results in the form of increased U-boatsinkings and changes in the enemy's submar-ine tactics were not long in coming. Thenavigational value of Tyne 271 also made itextremely popular. No wonder that theability to manoeuvre a ship with confidencein busy or restricted waters at night or inbad visibility which it bestowed savoured ofmagic to the sorely tried officers on escortwork in the Western Approaches Commandand elsewhere.

Nor were small ships the only ones tobenefit. The new surface warning setswere soon fitted in all types of ship thatcould carry them. Mast platform sites andlarger aerial reflectors were possible in thebigger ships which gave greater range. Beforeher gunnery sets came into play, the Dukeof York first located Scharnhorst with herType 273, a big ship version of Type 271.

The sensitivity of these sets was a revel-ation in surface warning. The detectionof a submarine's periscope during the trials

in H.M.S. Orchis was no freak result. Ship'slifeboat and rafts were located at night, enab-ling survivors to be picked up. Evengannets and other large seafowl producedechoes on occasion to the puzzlement of theoperators.

Turning the Tide in the Battle of theAtlantic

On the East Coast and later in the Channelcentimetric sets working both ashore in theC.H.L. system and afloat, gave warning ofand shadowed the elusive E -boat. But itwas in Western Approaches that Type 271scored its greatest successes, first stemmingand then completely turning the tide of theU-boat war in our favour at a most criticalperiod.

Time and again, U-boat commandersfound themselves being inexplicably detectedand attacked by the escorts before they hadtime to fire their torpedoes effectively. Itwas said in jesting tribute to " R.D.F." thatmany of the D.S.C.s awarded for the sink-ing of U-boats after the advent of Type 271,had " Admiralty Signal Establishment "stamped on the back of them.

Radar in the Merchant NavyAs soon as sets could be spared, Type 271

and 273 were fitted in merchant ships, begin-ning with the Queen Mary, Queen Elizabeth,and other large and fast liners, both' Britishand Allied. Type 286 P and the "suitcaseset " which followed it were also being fittedin the Merchant Navy to provide air warn-ing, a godsend to ships who could not affordto keep men continually closed up at theirguns. Merchant Navy radio officers weregiven special instructions in maintenance andD.E.M S. operators were provided.


A Radar -guided " Bat" bomb, as used by the U.S. Navy against the Yaps. The topillustration shows a Navy Privateer patrol bomber with a " Bat " slung under each wing.

Surface Warning DevelopmentMeanwhile, work on a more powerful mag-

netron was going forward. Passing theincreased power from the magnetron to theaerial was once again_ a serious problem.Cable feeders were not suitable and wave -guide technique was introduced in their stead.The theory of wave guides was establishedby Lord Rayleigh many years ago, but ithad never before been possible to producetransmission of sufficiently short wavelengthto warrant their use in place of cables.

Briefly, a waveguide is a metal tube thedimensions of which are related to the wave-length ,,kf the radio waves which it is desiredto pass through it, in such a way that theygo through the tube and come out of theother end with comparatively little loss inpower. Ingenious methods were used toensure correct reflection at corners in theguides and also to overcome the difficultiespresented by the rotating joints necessarywith revolving aerials. When the first setsusing waveguides were fitted, difficulty arosein convincing the electrical fitters and copper-smiths at the dockyards that these metal" flues " were electrical feeders not voicepipes, and that it was therefore within theprovince of the electricians to install them.However, after explanations, excellent co-operation was obtained.

P.P.I. " Picture " PresentationA naval version of the Plan Position Indi-

cator (P.P.I.) map type of display, previouslydescribed, was introduced. The value ofthe P.P.I. display was immense. It gavethe operator an instantaneous " view " allround the ship, providing at a glance thedisposition of own and enemy units in thevicinity. The picture it gave could be takenfrom warning sets used either for air or forsurface detection.

Coupling of the P.P.I. picture with theship's gyro compass provided an orientatedpicture with the " paints," as the echo indi-cations are sometimes called, on their truecompass bearings. If this were not done,the whole picture would be affected by eachchange of the ship's course.

More Aerial ProblemsCentimetric development had made it poss-

ible to use " cheese " or " dish " shapedmetal reflectors to focus the transmission intothe desired narrow beam ; but automaticcontinuous rotation was also essential forgood P.P.I. display which added furtherweight. An additional mechanical require-ment was vertical stabilisation to keep thebeam horizontal irrespective of the roll andpitch of the ship. This would permit offurther concentration of the beam in thevertical plane, giving more power.

The answer to the stabilisation problemwas found in the automatic pilot used byaircraft. The gyro element in this device,popularly known as " George," was adaptedfor use with the new aerial. The new aerialnow weighed nearly three-quarters of a tonand presented ship designers with a prettyproblem in top weight, but the difficultieswere overcome and the results justified allthe headaches.

Height FindingHeight finding with the metric wave air

warning sets can only be carried out in shipsby noting the fluctuations in strength of theechoes, as the aircraft passes through the lobes

the Radar beam. These lobes may bevisualised as taking the form of a giant bunchof bananas with the stalk at the transmittingaerial and the smallest banana at the bottom.

The echo increases in size as the targetenters a lobe, and diminishes as it enters thegap between the lobes. Results can be com-pared with a chart prepared from observa-tions made on aircraft flying at known heightsduring calibration trials.

But the highly directional beam now avail-able with the new centimetric set suggesteda less laborious method. If controlled ele-vation of the aerial were provided the setcould be used for determining the positionof aircraft in three dimensions instead of intwo, in the vertical plane as well as in thehorizontal, in fact, for direct height finding.

This called for extremely accurate meas-urement of the angle between the horizontaland a line drawn from the shin to the aircraftand necessitated vertical stabilisation of avery high order of efficiency, a mechanical

problem as formidable as any yet presentedby the electronic development of Radar itself.

Applying the Radar Picture ".In addition to height finding, the new centi-

metric set's P.P.I. man display made it avaluable target indication device on whichan accurate picture of all surface targets andlow -flying aircraft approaching the ship couldbe seen and the ship's armament brought intoaction accordingly.

Continuously rotating aerials and P.P.I.display were similarly providing improvedplotting information from the long range airwarning sets which enabled fighter directionto be carried out from ships in much thesame manner as on land.

In the skiatron, a magnified P.P.I. pictureis projected on a ground glass screen, thebright echo " paints " appearing as magentacoloured " sausages " which can be markedwith a pencil thus enabling plotting to becarried out on the display unit itself. Theadvent of Radar had now provided ships witha complete picture of all targets near at handand, in the case of aircraft, far beyond visi-bility. Surprise attack was virtually imposs-ible and the co-ordination of the Fleet'sdefensive and offensive armament was andremains largely dependent on Radar inform-ation alone.

Further development of centimetric Radarhas supplemented the " suitcase set " origin-ally designed for small craft and coastal

. forces, with a compact equipment givingP.P.I. display and a greatly improved per-formance. This set was produced in Canadaand has proved most successful. Otherdevelopments, inclading the application ofcentimetric Radar to gunnery, are proceed-ing and there is no sign of any slowing upin the astonishing speed of advance main-tained since the Navy's first Radar sets wereinstalled seven years ago.

I.F.F. and BeaconsThe power of Radar to detect aircraft at

far beyond visual limits and surface craft atnight and in poor visibility made it essentialto provide some method of identifying echoesfrom our own forces, i.e., " friendly echoes."

The answer was the device known as I.F.F.described in Section 5. The fitting of thistype of equipment in the Navy was extendedto practically all craft as soon as possible.Latterly, the requirement to distinguish in-dividual ships and aircraft has been met byproviding coded responses.

The development of fighter direction fromaircraft carriers and other ships fitted withair warning Radar is also largely dependenton the Radar identification afforded by I.F.F.

Radar beacons giving accurate informationof the distance between them and the interro-gator are of particular value in homing air-craft on the convoys for air escort work andin guiding them back to a " happy landing "on the flight deck of their present carrier.

Shore StationsNot all the Radiolocation development and

installation undertaken by the Navy has beenfor ships and aircraft, however. There wereimportant shore requirements, too. Thedefence of the main operational Home Fleetbase at Scapa Flow was the primary consider-ation in 1939, but it was evident that similarcommitments for "R.D.F." cover would arisein respect of all ports and bases liable toair or surface attack.

The Navy was therefore closely concernedwith the development of the C.H.L. coverdescribed in Section 4. Production of thenew C.H.L. equipment designed to interceptlow flying aircraft was not expected to com-mence until the end of the year, but Scapacould not wait.

Arrangements were made for a number ofpartially developed C.H.L. sets to be modi-fied at Cambridge for both air and surface

September, 1946

coastal watching, and these were installed atstrategic points in the Orkneys and Shetlands.The installation was carried out by youngCambridge scientists who were given specialtemporary commissions in the R.N.V.R. ;working under exceedingly difficult condi-tions on bleak and remote sites, they securedScapa Flow against surprise attack.

Meanwhile, the success of the decimetricteam in producing ,,the close range A.A.rangefinding set was providing the answer toanother shore " R.D.F.' requirement, thatfor a close range surface plot of all surfacecraft in the approaches to important har-bours and bases. Making use of the gunneryset's highly directional beam, a modifiedversion of the equipment was producedwhich, when installed at harbour entrances,enabled the position and movement of anycraft in the vicinity to be plotted. Thesesets were used in conjunction with the con-trolled minefields forming part of the harbourdefences and, in the event of attack, wouldhave shown when an enemy ship was pass-ing over any one of the mines which couldthen be detonated from the shore controllingstation.


quickly became apparent. In one instancetwo minutes' warning of the approach of atip and run raider, given by a Naval -mannedtrailer set near Dover, enabled 30o childrento take cover at Ashford, Kent. The schoolthey had just quitted was destroyed.

Similar Naval trailer sets working as corn-.plete mobile units with their own auxiliaryequipment carried -in lorries, did valuablework in the invasion of Italy and on D -Day,bringing their sets into action over difficultcountry and often under fire. They weremanned by Naval and Royal Marine per-sonnel in charge of R.N.V.R. officers. Thework called for considerable initiative andself reliance, as these units had to find theirown sites, arrange their communications andplotting organisation according to the currenttactical situation, and get into action as soonas possible.

Naval shore " R.D.F." Stations also didimportant work overseas. At the edge ofa t,tooft. icebound cliff on a remote cornerof Iceland, a special " arctic -proofed " Type271 was installed to keep day and nightwatch on the vital Denmark strait between

Iceland and Green-land, so that noGerman raider orstriking force couldpass without the Navybeing warned. Theset was landed in 1942and set up in recordtime by an expeditionled by Naval" R.D.F." officers.

The severe weatherfor which this part ofthe world is notedlived up to its reputa-tion. Until more per-manent buildings tookthe place of theoriginal camp it oftenseemed that the

During the first peacetime spring cruise of the Home Fleet last March,Radar was used for the first time in these manoeuvres. Approachingaircraft are picked up by Radar plotted in this room by the FlightDirective Officer. When they are spotted a warning is sent to all ships.During the manoeuvres a Mosquito ,attack was made on " Nelson,"

the 'planes using rockets and cannon.

By 1942, a complete inter -Service coastalchain giving cover against attack by surfaceships or low flying aircraft, had been estab-lished. The Navy contributed the stationsforming part of Scapa Flow's defences, sup-plied a large proportion of the requiredcentimetric equipment of the Type 271series, and provided W.R.N.S. plotters andoperators. This surface warning coastalchain was taken over by the R.A.F. andop.trated for the benefit of all three Services.

In the following year tin and run raidersbecame a serious menace on the South Coast.The new version of Type 271 using thehigher -powered magnetron transmitting valvewas in production, but ship -fitting was tem-porarily held up owing to difficulties withthe rotating waveguide joint required for theaerial. Numbers of these sets were hastilymounted on trailers and deployed round thecoast with Navy and R.A.F. crews.

Their value in detecting the sneak raiders

station would be-come airborne andbe swept off the cliffin the terrific wintergales. In 1944 ahigher -powered setwith P.P.I. displaywas installed. Lifeat such a place isnot unlike beingpermanently on anArctic expedition,but volunteers werealways forthcomingboth for the stationin Iceland and forothers on sites thereverse of chilly, butalso remote at Perim,near Aden, a n dChacahacre Island,Trinidad

425

" Special Sea Dutymen "It has been said of Radar- that no single

invention has so revolutionised naval warfaresince steam supplanted sail.

Join a ship, with us for just one operation." Special Sea Dutymen " goes the pipe, andthe ship makes ready for sea. A large propor-tion of these sea dutymen consist of R.P.and R.C. Radar operators, who check upon their equipment and report their readinessbefoxe we sail.

The surface warning Radar is ready tocon us out of harbour :f the visibility closesdown. Once at sea this set and the mast-head aircraft warning Radar for the Radarcomponent of the ship's look -out team,watching sea and sky with I.F.F. andinterrogators ready to identify friend fromfoe and in turn to identify us to our ownforces.

If there be a lurking enemy, ship oraircraft, the early warning provided by Radarenables us to get our blows in first, Ourgunfire is aimed by the gunnery Radar sets,feeding their precise measurements of rangeand bearing to the control machinery. Ifwe attack with airborne " strikes " carriedout by the Fleet Air Arm, our fighters andtorpedo bombers will be watched anddirected to the enemy by the same aircraftwarning Radar which is keeping constanttrack of the hostile aircraft. No matter whatthe activities of the King's ships, Radar isnow an essential tool for all their operations.

The three Fighting Services joined forcesas never before ; the Radio Board, directlyresponsible to the War Cabinet, gatheredtogether the leaders of research, productionand operational use and, under their guid-ance, inter -Services committees agreed oncommon requirements, research effort andsupplies. It may, perhaps, be said withoutfear of the superlative that Radiolocation wasGreat Britain's greatest single scientificachievement of the war.

The Captain on the bridge of the S.S. " Canterbury " looking athe Radar screen on the repeater.


A Scale ModelConstructional Details of a RealisticToy Runabout for a Small Boy

By B. W. FRANCIS

WHEN contemplating the constructionof this model the first thing I didwas to find out the wheel diameter,

wheelbase and track of a typical racing carsuch as an Alfa -Romeo or E.R.A. I thendrew out a plan view, side elevation andfront view of car I intended to make toapproximately one -eighth scale of the full-size car.

Wheel ConstructionThe chief difficulty was wheels, and these

I made by means of " formers," which Ihad to search for amongst junk in mygarage loft. I wanted the diameter of theseto be about rain., and then work out theproportion of the rest of car from this measure-ment. I found an old Ford Model BBflywheel and a bevel pinion housing from atwo -ton Ford lorry. With these and a pieceof oak I made the wheels. I chiselled outan oak block to the shape of the " tyre "and beat a circle of 24g. iron into it, turningit round continually while doing it. Thebevel pinion housing was then nailed rigidlyto the bench and a piece of 3 t6in. rodnailed into the bench, but about in. or soprotruding above the housing. The circleof iron was then placed on this and beatenboth inside and outside, the inside makingthe hub and the outside corresponding to theplace where rim should be. After alter-nating between these two formers severaltimes I had a circle resembling a side of a

Front view of the finished pedal -driven modelracing car.

wheel. This piece was then laid on to theflywheel and the edges beaten down over itall round (this lip being about Ain.). Thislip was then beaten right over, using theback of flywheel as an anflil. After makingtwo of these pieces I made a strip I in.wide to go round the wheel, then clampedthe two side pieces together with a 3 t6in.bolt with this piece between and then brazedall round the joints. For the rear wheels apiece of conduit tubing brazed right throughwheel does for hubs, and for the front wheelsI brazed on two old pedal -bearing cups.The accompanying sketch shows a sectionalview of the front hub, etc. The " tyres "are made by cutting off the tread from a26 x r; Dunlop carrier cover (one tyremaking two tyres for wheels). After cuttingto the right length, they are joined by twostaples made from It6in. steel rod. Ifthese are put in between the tread pieces thejoins are hardly noticeable. These tyres are;hen stretched on, and the complete assembly

Pedal Racing Car

is very strong and light and makesa very realistic and reliable wheel.

Mudguards are 26 x cycleones with centre bead.

Chassis DetailsThe body, chassis, exhaust pipe, etc.,

were made of 26g. sheet iron, the tail beingthree pieces welded together and beaten out.Chassis holes were cut with a chisel. Therear axle was made up and welded; wheeland crank bearings are Li ;z / 5 t6in. ballraces. Rear suspension consists of laminatedleaf springs, with two clutch springs encasedin a housing resembling a shock absorber,

Rear and underside views of themodel pedal racing car.

to left lock. In order to give thesteering wheel a position as nearlyvertical as possible a universal wasmade, and this can be seen in theinverted photo, just inside the bodynear the dash. Track rod ends and

drag link ends are car throttle ball joints.The brake -drum is a car piston headfixed to wheel (the one not operated bypedals).

Brake LiningThe lining is a slither from an old fan belt

riveted on. This brake is very efficient,the lever having a racing type ratchet. Thecar weighs 421b. complete and can be pedalled

Oak Block

Flywheel

Section etWheel(Front)

Details of

PinionNoosing

wheel construction.

acting as " helper springs." Front springingis of the independent type with a singletransverse laminated spring made up ofpieces of laths from a Morrison shelter andhardened. The steering wheel is also madeof laths brazed to a circle of 7/I6in. iron.Gear and sector for steering have teeth madewith a file, and approximately one turn ofwheel is needed to turn wheels from right

up a t in 8 gradient by my son aged 31- years.The seats I upholstered in rexine with theusual pleats, and the instruments are justpainted circles of iron. The windscreen isof safety glass, and is adjustable. The caris painted-the' body in maroon, chassisin blue, also the wheels. The exhaustpipe and mudguards are painted inaluminium.

FOR ENGINEERSScrew Thread Tables, 51-, by post 513.Refresher Course in Mathematics, 816, by

post 9!-.Gears and Gear Cutting, 6!-, by post 616.Workshop Calculations, Tables and

Formulae, 61-, by post 616.Engineer's Manual, 1016, by post III-.Practical Mechanics' Handbook, 1216, by

post 131-.

Engineer's Pocket Book, 1016, by post III-.Wire and Wire Gauges (Vest Pocket

Book), 316, by post 319.Screw Thread Manual, 61-, by post 616.

Published byGEORGE NEWNES, LTD., TOWER HOUSE,SOUTHAMPTON STREET, STRAND, W.C.2

September, 1946 NEWNES PRACTICAL MECHANICS

The CalculatinIts History and Basic Principle

By F. W. COUSINS(Conciiiided from page 391, August issue.)

THE " Millionaire " calculating machinepatented by 0. Steiger was the firstmachine to operate by true

multiplication.The machine fundamentally consists of

three parts :(a) The multiplication mechanism.(b) The carrying mechanism.(c) The recorder.

(a) The multiplication mechanism consistsof nine tongued plates originally designed byBollee. They are in fact mechanical repre-sentations of the multiplication tables fromone to nine. Each individual plate is shownin Fig. 21.

(b) The carrying mechanism consists ofparallel toothed racks as shown in Fig. 22,where the mechanism of the machine ispresented in simplified form, and the indexbelow refers specifically to this figure.

Crank .. CMultiplication Lever .. LMarkers .. M M etc.Result Dials . D D2, etc.Pinions .. . 131, Pt, etc.Tongued Plates . TRacks .. Z1, Z2, etc.Bevel Wheels .. B

That the drawing should be succinct theaxle and result dials for pinion P only areshown, but these are duplicated eight timeson the actual machine.

If now any pinion such as P, is movedby its marker M5 across the toothed racks,Z1, Z2, Z3, etc., that pinion is broughtinto correct relationship with the digits ofthe multiplication table from one to nine(there being nine racks, Z,-Z,). Manipula-tion of the multiplication lever L bringsthe desired tongued plate T (x>: 5 in Fig. 21)into position. Rotation of the crank C thruststhe tongued plate on to the racks Z Z,, Zetc., causing them to be moved according tothe undulations of the plate T. The pinionwheels P arc thus rotated in accordance withthe linear travel of the racks and the bevelgearing B records this travel by rotating theresult dials D.

In the actual machine a clever constructionof the crank mechanism arranges for theracks to be thrust against the tongued platetwice for one rotation of the crank, impartinglinear travel to the racks for the tens undula-tions and the units undulations on thetongued plate ; this is not shown in Fig. 22.

Babbage Differential EngineThe differential engine of Charles Babbage

provided an interesting departure from thegeneral trend of thought. Babbage foresawthe value of an engine which would printmathematical tables and set to work toperfect such a mechanism.

This type of engine would be of great use

7.c.r-co-6,1x xi

-A-Anal. -IL X 2N * C. ON * S2 1

to a maritime nation suchas Britain, which had spentmore money than anyother nation on the studyof longitude and thepreparation of Lunartables and the like fornavi gational aids.Accordingly the BritishGovernment financed hisinvention, but misunder-standings which occurredprevented the successfulcompletion of the engine.

The basic principle ismost easily shown from astudy of simple tabularvalues and the accuracy ofthe table as a whole. Theobject of the differentialengine was to calculateand print a series oftabular values. To dothis it used the system ofdifferences, which hadthe advantage of givingat any point a readycheck on the accuracyof the entire series oftabular values-a mostpleasing device.

Circumferences ofCirclesConsider the table of

circumference of diverscircles when the diameteris changing in equalintervals.

Machine427

Babbage's difference engine, showing the multiplicity of gears andnumbered drums.

Diameter Circumference3.1416

2 6.28323456 18.84967 21.99118 25.1327

There are two ways of computing such atable :

(a) Multiply the diameter in each line by:s (3.1416).

(b) Start with 3.1416 and add 3.1416 ateach succeeding change of diameter of I unit.

The advantages are then found to be asfollows :

Case (a).-Each value capable of error dueto errors in multiplication. An error in onevalue will not alter any other value.

Case (b).-Any error in any value willseriously alter all following values ; but ifwe calculate the final term of the tabledirectly we have a check on the accuracy ofALL the figures in the entire table. Nosuch advantage as this occurs in system (a).

julitt int x x 4.3 g31[4-

L x x 5CSR n

ON '" 7r, n9, ,9,

x 6

Consider a table of square numbers,I, 4, 9, 16, 25, 363 49, 64, etc., and a table of1st order differences and 2nd order differences:

9.4248 No. Square 1st order 2nd order12.5664 diff. cliff.15.7080

tkUatiritf .4;

Fig. 21.-The Bake tongued plate system.

xx8

x x 9

I I2 4 3 2

3 9 5 2

4 16 7 2

5 25 9 26 36 II 27 49 13 28 64 15 2A table of cubes with 1st, znd and 3rd

order differences gives a similar state ofaffairs.No. Cube 1st order 2nd order 3rd order

diff. cliff. diff.I I I2 8 7 63 27 io 12 64 64 37 18 65 125 61 24 66 216 91 30 6

It will be seen that tables of this kind can becarried to any extent by the simple additionof successive differences if the constantdifference is known.

An example from Babbage himself readsas follows :

Table for y- x2+ x +41.Then, the table of differences for the valuesof x from 11 to 14 are :

L, 6.2II 17312 197 24 2

13 223 26 2

14 251 28 2

It has been found that all tables most


Fig. 22.-Simpltfied mechanism of the Millionaire machine. (Inset exterior view.)

important for practical use relating toastronomy and navigation can, although theymay not possess any constant difference, stillbe calculated in detached portions by thismethod.

The machine partially assembled appearsin the illustration on the preceding page.It embodied some of the finest Englishworkmanship and the gearing is of superbmanufacture. As the tables show inelementary fashion so the machine operated,calculating by the continual addition ofnumbers in several columns, the results beingcarried over to other columns. The wholeengine upon completion was to have 20places of figures of six orders of differences.

Differential AnalysersThe mechanical integrator usually makes

use of a variable gear, the gear being able tovary continuously. Kelvin explained theuse of the mechanical integrator for thesolution of differential equations, but failed toperfect a really satisfactory machine due to thelow -power output from the friction drive.

Machines of this basic type called dif-ferential analysers are now in existence, andthe difficulty of the low -power output fromthe friction drive of the integrator has beenovercome by the use of a torque amplifier.

The basic unit of the differential analyser isthe integrator, and this is shown in dia-grammatic form in Fig. 23.

Fig. 23.-Integrating wheel.

The vertical wheel is driven by the hori-zontal disc. The disc is so mounted that thecontact point between wheel and disc can bevaried at will.

The gear ratio is thus proportional to thedistance from the disc's centre to the pointof contact of the wheel.

Any continuous gear will serve as an

integrating mechanism. If the ratio " r "of a variable speed gear is varied as the drivingshaft is rotated the total rotation of the drivenshaft is f r d x.

On the latest machines a graph can beplotted on an inputtable and a photoelectric cell follows thegraph with greataccuracy.

This motion istransmitted by complexgearing to the disc andwheel shown in Fig. 23,giving the lateral dis-placement d2. A specialgeared pencil marks asolution on an outputtable and provides thesolution to the inputtable values. (SeeFig. 24.)

Machines are con-tinuously beinginvented to dealwith differential and integral equations,others to aid harmonic -analysis and solvecomplex simultaneous equations. This

September, 1946

article cannot hope to deal with such anarray. It will, however, become obvious to thereader that if a machine or device has amotion or characteristic which can berepresented by a mathematical equation,then that motion or characteristic is a toolfor the possible solution of that equation.

Useful BooksTo the reader whoatesires a more detailed

account of the many machines I give asynopsis of the literature I have found avital source of information :

" Calculating Machines," by K. S. Phillips,B.Sc. Vol. 12, No. 45. Institution ofElectrical Engineers.

" Mechanical Integration : 34 Kelvin Lec-tures." By Prof. D. R. Hartree, M.A.,Ph.D., F.R.S.

Babbage's Calculating Engine, 1889,"by H. P. Babbage.

" Newcomen Society Transactions," vol.13-14, 1932, 1934.

" Encyclopxdia Britannica."" Arithrnetik, 1678," by W. Leybourne." Calculating Machines," by Feldhaus.Catalogue of Science Museum.

Mathematics I." Modern Instruments," by Horsburgh." Nature," vol. 149, 1942, pages 462-5;

vol. 150, 1940, page 508." Pascal : Life and Genius," by Morris

Bishop." Calculating Machines," by L. T. Comrie.Acknowledgments are made to the Controller,

H.M. Stationery Office, for permission to

Fig. 24.-Diagram of a type of differential analyser.

reproduce the photographs on pages 342,389 and391 from the official Catalogue of the Collectionsin the Science Museum (Mathematics).

Power for the Brabazon I"FIRST official news of the engines to

power the giant Bristol 167 or" Brabazon I " air -liner was given by Mr. JohnWilmot, the Minister of Supply, recently inanswer to a question in the House of Commons.Listing the British civil aircraft now inproduction and those likely to be in productionbefore the end of 1947, the Minister revealedthat the " Brabazon would be powered byeight Bristol Proteus engines of 3,500 b.h.p.each.

The Proteus is a gas turbine airscrew unit,and this was the first official intimation thatBristol had in hand a gas turbine unit additionalto their Theseus I, preliminary details ofwhich were announced last December.Mounted in pairs and completely buried inthe wings, the eight engines will drive fourcontra -rotating propellers, giving a cruisingspeed of 35o m.p.h., at 35,0ooft. plus.

The Minister also disclosed the " Brabazon "will have an all -up weight of 284,0001b.,a range of 5,000 miles and night accommo-

dation for 72 passengers. Previously theall -up weight had been given as I to tons;the figure given by the Minister, therefore,exceeds this by 15 tons.

Radio Control of ModelsTT has now been announced that radio

control of models is again permitted.The G.P.O. have allocated a frequency of460.5 me s for this purpose, but no licenceis to he issued at present. Before such apparatusis brought into use, however, notificationmust be sent to the G.P.O. Such notifica-tion should be addressed to the Radio Branch,W.2 6, Engineering Department, G.P.O.,London, E.C.i, quoting reference 16311'46.Any radio equipment designed for the remotecontrol of models must be of such a naturethat the maximum power radiation does notexceed 5 watts and that there is no radiationoutside the limits of 460-461 me s.


Flameproof Flexible PipesA Noteworthy Dunlop Invention for Eliminating Fire Risk in Aircraft

ACONSIDERABLE quantity of data hasbeen amassed, particularly during thewar period, °I -lithe cause and severity

of aircraft crashes. From this data it hasbeen established that if the fire risk can beeliminated the proportion of serious crasheswould be very considerably reduced.

The majority of fires in the air are inductionfires, which, of course, take place in theengine nacelle, and can be isolated by afireproof bulkhead. A considerable amountof development work has been done on fireextinguisher systems, but it is quite apparentthat, with an induction fire, it will be necessaryfor the engine to function satisfactorily for ashort period during which the airscrew isfeathered, petrol supply switched off, etc.,and the fire in the nacelle extinguished.

The use of flexible pjpes for fuel and oilsystem on aircraft engines is now well

A special rig for testing the fire -resistingproperties of the pipe. The pipe has to withstandthe flame for a period of five minutes without

leakage.

established, and it is quite obvious that theusual type of flexible hose would rapidly failif exposed to fire, particularly a petrol firesuch as occurs in the engine nacelle. In viewof this it has been necessary to develop aflexible pipe which will withstand not onlythe normal arduous conditions of service suchas hot oils and fuels, vibration, etc., but alsoan engine fire without failure for a periodwhich will allow fire combative measures tobe taken.

Testing the PipeA considerable amount of work has been

carried out in order to determine a suitabletest which can be applied to a flexible pipein order that it will meet these conditions ofservice. The following test is at the momentestablished.

The flexible pipe, fitted with the appro-priate fluid, i.e., petrol or oil, at the maximumpressure likely to be met in the particularsystem in which it is to be used, is bent toits minimum bending radius. The hose isthen subjected to the flame of a blow -lamphead of defined nozzle and other dimensions,directed on the outside of the bend of thehose at a specified distance from the surfaceof the hose. The flame temperature is in theregion of t,000 deg. C. The hose mustsatisfactorily withstand this flame for a periodof not less than five minutes without leakage.

The Test Apparatus UsedVarious types of test rig have been tried

in order to obtain a consistent flame. Theapparatus now used comprises a fuel metering

and control unit coupled to a special blow-lamp head. The fuel is metered to the lampat a constant pressure, and the rate of burningis carefully controlled, ensuring uniform flametemperature. During the test the internalpressure in the flexible pipe increases due tothermal expansion of the fluid within thehose. Arrangements are incorporated in therig to enable this excess pressure to be bledoff during the test, and to maintain areasonably constant pressure in the hose.

The severity of this test can be imaginedwhen it is pointed out that within a fewseconds of the start of the test the outercover of the hose becomes a glowing red-hotmass.

Two types of hose have been developedwhich will satisfactorily meet the require-ments laid down. The more popular is thewire -reinforced high-pressure type of hose.

This comprises a syntheticlining tube over which is braidedsuccessive layers of cotton, hightensile wire and cotton, thewhole being finished with anouter cover of synthetic rubberspecially compounded to resistthe action of the flame. Incertain cases a layer of asbestosbraiding is incorporated in theconstruction in order to furtherimprove the flame resistance.

Synthetic Lining TubeThe second type consists of

a synthetic lining tube, speciallycompounded to resist the actionof oils, fuels, etc., which isreinforced by braidings of aspecially treated heat -resistant

-- cotton. Incorporated in the con-struction are layers of heat -resisting materials,such as glass fibre and asbestos, the outsideof the hose being finished with a similarflame -resistant synthetic cover to thatpreviously mentioned.

The first -mentioned type is to be preferredin that it is possible to maintain a smaller

outside diameter for a given bore size; at thesame time it should be borne in mind thatthe weight is somewhat greater owing to theuse of high tensile wire as a reinforcement.

Both oL the above types have been success-fully subjected to the most stringent tests.Tests have been recorded where the high-pressure type of pipe has withstood the flametest for a period in excess of go minutes, withan internal pressure of 30o P.S.I. withoutsigns of failure or leakage.

SUSPENDED BOMBSA NOTABLE device which relates to the" subject of bombs has been patented bya British inventor. He points out that inaircraft battle tactics it frequently happensthat the enemy approaches from behind.

The object of the additional inventionis to provide an effective defence against thismethod of attack. The new proposal is tolay a screen of floating bombs in the wakeof the aircraft threatened from the rear.

The bombs are each fitted with a para-chute attachment so that, when dischargedor projected from the defending aeroplane,the bombs are suspended in the path of theenemy.

In the case of furnishing a barrage againstair -raids, these bombs may be launched bya number of aircraft.

A supply of cartridges, each complete withprojecting charge and bomb with parachuteattachment, may be carried in any suitablepart of the machine, such as the tail. Andthey may be fired either in series or groupsfrom the bomb projector.

The bomb projector is of the barrel -lesstype in which bomb -containing cartridgesare carried in sleeves serving as tubes forprojecting the bombs. And they are accom-modated in links connected into a belt passingover a rotatable drum. This co-operateswith a multiple firing device for simultaneouslyfiring a number of bombs. The device isautomatically cocked by the rotation of thedrum.

A mechanic applying a blow -lamp to the piping as a further test of its flame -resisting properties,


THERE are five or six miniature slideprojectors coming on to the market.These instruments will be ,expensive,

but the home constructor can obtain quitegood results by adapting existing apparatus.

The projection of a transparency is thevery finest way of reproducing a photograph,and this is especially true of colour photo-graphs. It is relatively easy to produce areasonably satisfying transparency in colour,and at a low cost, but an equally good colourprint is vastly more difficult and expensive.For education and some industrial purposes,also, a still picture is as good, or even better,than a moving film, and very much lessexpensive.

But the weight and bulk of the old-fashioned full-size lantern slides, and theirhigh cost in commercial production, hasled to much research into the use of miniatureprojectors, using strips of 35 mm. film, oralternatively, small size slides.

(

Fig. 1.-Double condenser sys

The Sizes in UseThere is some confusion about sizes, due to

the fact that the original film -strips producedmainly for educational purposes carriedpictures the same size as the normal 35 mm.cinema, viz., 18 mm. by 24 mm. As avariation, one firm uses the square shape onthe same film, picture size 24 mm. eachway.

Amateurs and professionals, apart fromschools, however, mainly employ the normalcamera size, 36 mm. by 24 mm., i.e., twoframes of a cine film.

The necessity for preserving colour filmsof this size from damage led to the use ofglass slides tin. square (the actual size of theglass is 49.3 mm.). Lantern plates of this-size can readily be obtained, though theyare only slightly cheaper than the full size,owing to the thin glass used, and to thehandling costs, etc., being nearly as great.On these can be printed either optically orby contact, pictures up to about 4o mm.square.

Strip film reduces the cost of the com-mercially -produced lantern slide by 90 percent* and weight and bulk by 99 per cent.With glass slides the saving is not nearly sogreat, but it is very considerable.

The Miniature ProjectorIt is useless for the experimenter to attempt

to design or adapt his own apparatus unlesshe understands the principles of projectionand the peculiar difficulties of the problem.Nor, until he has tried for himself, will herealise the reason for the cost and complicationof the best projectors on the market.

Th.,- IlluminantThe ideal light source for use with a

condenser would be a point source (did notEuclid say that a point had no magnitudewhatever ?) No filament lamp approaches

Slide

tern.

Miniature Slide ProjectorsPresent Position and Principles as a Guide for Constructors and Purchasers

By M. K. KIDD

this standard at all closely. The best thing isto employ a low voltage lamp, which can havea short thick filament. Lamps are now beingproduced with a so-called " solid source " in12 volts up to 25o watts and in 24 volts up to400 watts. However, too watts is a commonsize, and many film -strip projectors are inuse which use only 24 or 36 watt automobiletype bulbs, which suffice in a well -darkenedroom.

The current is usually supplied by a trans-former. Although not usually provided,there should he extra tappings, or a resistanceto provide both for a lower voltage -to usewhen starting, and a higher voltage to allowthe bulb slightly to be overrun when extralight is required.

The Heat ProblemThe larger bulbs generate great heat ; this

problem is dealt with in two ways : ventilationand filtering. If ventilation to the lamphouse

is inadequate, the bulbwill get too hot, andits life will be reduced.In certain cases afan is provided-an

_ excellent scheme. Butno fan can preventthe heat rays frombeing focused uponthe film along withthe light. Therefore, thebest manufacturers fita heat filter. A newBritish glass is claimed

to absorb 8o per cent. of the heat, but lessthan 15 per cent. of the light.

Gathering in the LightA mirror is a most important item, and

the experimenter and constructor must onno account omit to fit one. The best areof silvered optically -worked glass, but metalones are sometimes used. They have towithstand considerable heat, and must becapable of minute adjustment and firmfixation.

The condenser usually consists of two pianoconvex lenses fitted with their convex facesnearly touching (Fig. s). Somewhat greaterefficiency, however, may be obtained fromvarious combinations of three lenses. In onesystem the lens nearest to the slide may bechanged to suit the size of slide being shown.Triple condenser systems (Fig. 2) are,unfortunately, not generally on sale, butordinary lenses are plentiful and not expensive.The cheaper ones are moulded, and quiteeffective. They are usually slightly greenishin tint, but this is of little importance.Better lenses are clear, and optically worked.

Light is scattered and lost whenever it entersand leaves a glass surface-this trouble is minimised bysome manufacturers by" bloom-ing " or coating with a fluoride.(Present price, los. per surface.)

The LensThe best lenses arc anastig-

mats made specially for pro-jection, but there are manysimpler lenses of the Achromator Petzval types which pass avery good amount of lightand give passable definition,especially in the centre. There-fore, one of these, if it gives apicture large enough, may prove

quite suitable for a miniature projector. Theusual aperture of projection lenses is between173 and f'4. The fact that a lens has a fasterspeed calculated as for camera use does notmean that it will be certain to pass more lightwhen used for projection.

As for focal length (to determine approxi-mate focal length of a lens, use as a burning

"glass, and measure the distance) Sins. to 4ins.is the size normally fitted. Two-inch lensesmay be used in a very small room or forprojection through a translucent screen. For

- a small hall 6in. lenses may be fitted.A fast camera lens will work more or less

satisfactorily, but beware of heat damage.

SlideholdersTwo-inch glass slides may be used in

adapters, or holders of the usual type, but it isquite sufficient merely to push them througha suitably -grooved holder, either vertically orhorizontally (Fig. 4). Light springs arenecessary to ensure that the slide is held incorrect focus.

Film -strip HoldersThese are a greater problem, which

increases with the heat of the lantern and theaperture of the lens. The picture is printedupon a strip of ordinary non-flam 35 mm.cine film, with the usual double sprockets,the " business " side being inside the curl.A few inches are provided at each end forthreading purposes.

The small size films have all their picturesone way, so that the film merely travels down-wards during projection, but 36 mm. by24 mm. transparencies depend, of course, onwhich way the camera was held. To show thissize, therefore, the holder must be made torotate through 36o degrees ; in some cases,the film -holder is attached to the front of thelantern-in others it forms a unit with thelens.

It will be realised that the film will soon bedamaged -by scratching unless great care istaken. The design should be such that neitherside is touched while moving, except at theedges. In the better projectors a pressure glassor frame is automatically raised before thefilm is moved on to the next picture. In these,too, a sprocket is employed to engage withthe holes in the film- to move it, instead ofmerely winding it on to the take-up spool,a method which causes more wear and isinconvenient when it is desired to turn back.

Adapting Existing ApparatusThe first thing to do is to see if a suitable

lens is available. A lens of 6in. focal length(see above) will just suffice in a hall or school-room, but not in the home. It is not practicable,in most cases, to obtain a larger picture by

AnastgmerLens

Filter

Fig. 2. ---Triple condenser system (Pullin Optical Co.).

September, 1946

using a supplementary lens, but by all meansexperiment-the object lens from an operaglass is the sort of thing required.

Next, to hold the slide or film. Start withan ordinary slide masked down to 36 ;; 24mm.,if you have no miniature transparencies.When satisfactory results have been achievedit will be time to construct a filmholder.

As it is now only necessary to illuminatesuch a small area, try adjusting the lamp andreflector to the best advantage, which maywell double the intensity of the light. It ispossible in some cases to secure good resultsby moving the slide forward, perhaps veryconsiderably, into the cone of light.

It will be found that the lamp is usuallysome 6in. from the condenser, and that


Lay a length of film along the zin. side andmark out the edges of the film and the extremewidth of the picture.

Cut an aperture centrally 24mm. wide and36mm. long unless only small size slides areto be shown, in which case 18mm. will do.A tension file will be found useful in cuttingthe hole.

Five spindles 2in. long and ;in. diameterare now fastened into position, either bythreading or by soldering.

In order that the picture side of the filmmay not touch, two thin strips of brass aremade to reach nearly up to the lines already

drawn to denote thepicture width. Fastenedby the same screws aretwo narrower pieceswhich nearly reach thelines showing the widthof the film. That is,the bearers will be25mm. apart and theguides 36mm. part.

The pressure plate is0 of 'any suitable metal,

but not too heavy. Ithas an aperture tomatch that in theframe, and is held inposition by two arms.These arms are fastenedto the pressure plate attheir lower ends bysmall bolts ; play isnot necessary, but

- "

-2"

Fig. 3.-General arrangement and side view of a simple film -stripholder.

most of the light goes off in any directionbut the useful one. This can only be improvedby moving the lamp closer-which necessitatesa condenser system of shorter focal length.For small slides this is now easily possible,and a new pair of lenses 2.in. or Sin. indiameter should be obtained and fitted inplace of the large ones. The effect will bestriking, as the lamp will now be placed muchcloser, and greatly improved illumination willresult. Adjustment of all parts will be foundmuch more critical, and careful experimentwill achieve the best result. Here are twohints : (I) adjust the lamp before using thereflector at all ; (2) place a piece of groundglass or paper in the position normallyoccupied by the lens (in focus) and secureimages of the filament upon it, from both lampand mirror.

In order to fit a film -strip holder to anordinary lantern it may be necessary toremove the lens, together with its tubeor bellows from the front of the body, andremount them on a new support. Exactdirections cannot be given as types vary somuch, but generally it will be necessary toextend the baseboard a few inches. No matterif there remains an open gap-modern lanternsconstructed on the optical bench principlehave no bellows and very little lens tube,and are very much cooler.

Film -strip HolderThis holder is built upon a strip of metal,

preferably brass at least I ,16in. thick, 7,,in.long and 3 wide, bent to angle shape,one part being 2in. inside the bend (Fig. 3).

a

they may need adjustment. Their upperends are fastened to a length of tubing whichfits over the rod. A coil spring is fittedas shown. It is desirable to fit.two narrow stripsof metal to the back of the pressure plate tohold the film by the edges. The whole trackof the film is thoroughly smoothed andpolished.

The take-up spool is of wood or metal notless than in in diameter. The end of thefilm is tucked under asemicircular clip fastenedto the middle of the spool,which carries a wheel ordisc I lin. in diameter atits end. A simple ratchet isuseful.

The film is loaded fromthe side, by merely raisingthe pressure plate.

The rotating device, ifrequired, can be added andplaced between the holderand the lantern ( Fig. 5;.

A disc 21in. in dia-meter, having an aperture40 32 mm. cut in it, ismounted in a ring 3 lin.external diameter and 2l in.internal diameter to fit thedisc.

It is best turned in brassor light alloy 1 or 3'16 in.thick, but plywood isfairly satisfactory, and aready-made substitute canbe found in the upper

r

431

part and lid of a golden syrup or similartin.

It will be seen that the filmstrip holder isspaced about Ain. from the disc. This ispartly to allow clearance for the clips whichretain it in place and partly to provideventilation.

The same holes and bolts which fasten thefilm bearers and guides serve to hold therotating disc to the holder.

AddressesVisual Information Service, 168a, Battersea

Bridge Road, S.W.1t and Newton and Co.,Ltd., 72, Wigmore Street, W.', supplyfilmstrips on travel, religious and generaleducational subjects. Usually there are 30or 4o pictures on a strip, and the price worksout at from id. to 3d. per picture. These firmsmake strips to customers' order at 31d. to6d. per picture, and also supply projectors.

The following make miniature projectorsas well :G. B. Equipments, Ltd., Wardour Street, W.I.Aldis, Ltd., Birmingham.Pullin Optical Co., Ltd., Great West Road,

Brentford, Middlesex.Common Ground, Ltd., Sydney Place,

S.W.7.The following supply optical goods, new

and secondhand :Broadhurst Clarkson and Co., Ltd., 63,

Farringdon Road, E.C.r.Misc. Trading Co., 135, High Holborn, W.C.r.

Fig 4.-Push-through holder for miniature glass slides, to replacefull-size carrier.

These firms make special lenses forprojection :Dallmeyer, Ltd., Willesden, N.W.ro.Aldis, Ltd., Birmingham.Pullin Optical Co., Ltd., Great West Road,

Brentford, Middlesex.The following firms supply projection

bulbs :Siemens, Ltd., Upper Thames Street, E.C.e.General Electric Co., Kingsway, W.C.2.

0 " 2"

Fig. 5.-Rotating device for film -strip holder.

-7"


Inventions of InterestBullet -resisting Clothing

THE evolution of armour for the body hasnot yet culminated in an absolutely

bullet-proof covering, but considerableprogress has been made -in the directionof shielding the wearer from bullets, shrapneland splinters caused by firearms andexplosions.

An inventor has been impressed with thefact that such a covering has not alwaysbeen convenient to remove. The protectinggarment has been heavy to draw upward.In the case of a wound, it might even haveproved an obstruction to access to the injuredpart.

Accordingly, the inventor in question hasdesigned a garment in which the front partand the back part are connected together in adetachable manner. He proposes the useof short lengths of manganese steel or otherbullet -resisting material in plate form.

To Train Horse RidersASUPER -ROCKING -HORSE has entered

the field. This equine wonder emanatesfrom the brain of an American citizen whohas applied for a patent in this country.The animal belongs to the family of mechanicalexercising horses.

The principal aim of the inventor hasbeen to produce a means whereby exercisesmay be taken which will simulate the variousmovements performed in the riding of ahorse. It is so contrived that there canreadily be imparted to one's arms, legs andtorso the movements occasioned when onerides a horse at a walk, trot, canter or run.

This exercising horse is operated bymuscular motion of the legs, arms andbody rather than by mechanical means.Consequently, the rider can ificrease ordecrease the speed of the action at will, andis not required to respond to movementscaused by a motor or other mechanism suchas is employed in previous types of exercisinghorses.

Safe for the YoungPRIMARILY the device is designed for

children. And it is so contrived thatit can be used by either adults or juvenileswithout danger.

Not only does the horse afford exercise toall the muscles of thee body, but it gives therider an opportunity of using his skill andjudgment. The inventor affirms that, whileit enables a child to develop those qualities,it also helps the youngster to co-ordinate themuscles of the arms, legs and other parts ofthe body.

Standing with each of his feet upon astirrup block, the rider leans forward in ariding posture holding the handle -bars atthe sides of the neck of the animal. He thenmoves or swings his body up and down,bending his knees and at the same timepushing and pulling the head of the horsebackward and forward.

This action puts the stirrup springs andthe horse's head into oscillating motion.As a result, the rider automatically moveshimself up and down in a manner resemblingthat of one riding a trotting or gallopinghorse.

Fire FighterWHEN an aeroplane crashes, the usual

sequel is that the ill-fated machine israpidly enveloped in flames. To deal withsuch a catastrophe is one aim of a mobile

The information on this page is speciallysupplied to " Practical Mechanics " byMessrs. Hughes & Young, Patent Agents, of7, Stone Buildings, Lincoln's Inn, London,W.C.2, who will be pleased to send free toreaders mentioning this paper a copy of theirhandbook, " How to Patent an Invention."

fire-fighter which has recently made itsdebut.

This contrivance consists of a vehicledriven by an internal combustion engine.It comprises a tank holding a sufficient supplyof water, a pump of adequately large capacityand mechanism for using the propellingpower of the vehicle to work the pump.

There is a hose connection to the pumpto direct and deliver water, liquid chemicalsor gases, separately or in conjunction, inlarge or small quantities from one or severalpoints, quickly and with efficiency.

This fire-fighter can be moved speedily,owing to its having the requisite power andits centre of gravity positioned low on thechassis.

September, 1946

housing. There it is held by a spring plungeror other fastening device.

The lock bolt is spring pressed and entersa recess in the steering column or in a platethat is brazed or otherwise fixed to it.

The end of the bolt may bear against thewall of the steering column within the recesswhen in its locked position.

Bombs Dropped in Water

ALTHOUGH hostilities have ended, thesupply of military inventions has not

entirely ceased. Here is one which is thesubject of a recently accepted applicationfor a patent in this country.

The device in question relates to bombsdropped into water and more particularly tofloatable bombs which are required to explodewhen rising in the water at a short distancebeneath the surface.

The inventor affirms that in order tominimise the errors in hits by under -waterbombs it is advantageous to obtain a highterminal velocity in air and a low terminal

The giant Northrop Flying Wing XB-35 is wheeled to a runway for its first taxi -test in preparationfor the initial test of flight, which took place in the United States recently.

There is a bank of compressed gas cylindersfor direct use in quenching particular typesof fires.

The tank covers the greater portion of thefloor of the chassis, and a foam generatorfeeds foam into the outlet from the forcepump.

" Mind Your Bike"THE bicycle thief is ever with us. To put

an obstacle in the way of this culprit acycle lock with new characteristics has beensubmitted to the British Patent Office.

In this instance the housing for the lockis brazed, or fixed in a similar manner,entirely within the top or bottom tube ortube liner where the tube enters the top orbottom head lug of the tube that containsthe steering column. And the lock is of sucha nature that it can be inserted in the downtube and then pressed laterally into the

velocity in water. Consequently, the depthto which the bomb sinks is limited and thetime of immersion for a given upward velocityis reduced.

In addition, the low terminal velocity inwater, by limiting the depth to which thebomb sinks, allows it to be used in rathershallow water.

The new device consists of an aerial bombprovided with a streamlined false nose coveringthe nose proper, which has a greater drag.The false nose serves to reduce drag whilethe bomb is falling through the air and todecrease the shock of impact.

The false nose, which may be madesomewhat fragile, disintegrates under internalpressure after the nose of the bomb hasentered the water. The nose proper increasesdrag and modifies the under -water travel ofthe bomb as required.


The Annals of Electricity -10Ampre's

IT was James Clerk Maxwell, himself atowering electrical genius of lastcentury, who first. described Ampere

as " the Newton of Electricity," an appella-tion which is certainly as apt as it is acomplimentary one. For just as Newton'sinvestigations and calculations served to laythe foundations of physics and mechanics,so also did the researches of the ingeniousAmpere, >by their clucidatien of the lawsgoverning the action of electric currents,bring into being the practical science ofelectro-dynamics which deals with electricityacting as a motive force, a science which,indeed, culminated in the invention of thedynamo and the electric motor, and therebyintroduced our present-day electrical age.

Yet, curiously enough, electricity was onlya sideline with Ampere. His interest coveredalmost the whole gamut of the sciences.He was' a botanist, a mathematician, aphysicist, a devoted student of naturalhistory, a chemist, an astronomer, a classicallinguist, to mention only a few of the subjectsin which Ampere made himself prominent.Nevertheless, if Ampere had not turned hisattention to electricity we should never haveheard of him in the ordinary way of things.The " amp.," that conveniently abbreviateddesignation of the unit of electrical quantity,which is Ampere's most lasting memorial,would never have come into existence.

Andre Marie Ampere lived a crowded life.Invariably he had half a dozen irons inthe fire at any one time so that it is impos-sible for us at this period of paper scarcityto trace out his career in any detail. Hewas born in Lyons, in the south of France,on January 22nd, 1775, the only son of oneJean Jacques Ampere, a well-known mer-chant of that town. Jean Jacques had beenin a prosperous way of business, and soonafter his son's birth he retired from activetrade and settled down as a countrygentleman in a village not far away.

An Infant MathematicianAndre Marie, the future electrician, turned

out to be an almost uncannily precociousyoungster. His innate mathematical abilityshowed itself the earliest. When he wasbarely seven years of age he was doing longcalculations with kidney beans or pebbles,and, having acquired the ability toread, his first choice of books took the formof treatises on algebra. When he was twelvehe was battling with Euler's and Bernouilli'smathematical works on the differentialcalculus, treatises which were written inLatin, which language he mastered especiallyfor the purpose of comprehending these twogreat masters.

Advances in Electrical Science

There was no regular schooling forAmpere in those days. He seems to havelearned what he liked, being aided in theprocess by his father and by the kindlyAbbe Dubarron, the learned librarian of the

Andre Marie Ampere.

College of Lyons. If was Ampere's wontin after life to remark that at the age ofeighteen he knew about as much mathe-matics as there was to learn, whilst it isa fact that at about this age he had readthrough and apparently thoroughly digestedthe great French Encyclopaedia of Diderot

A wire helix or " solenoid" which under, theinfluence of an electric current behaves like a

magnet.

and D'Alembert, a colossal compilationrunning into 20 folio volumes. This great.treatise on universal knowledge Amperedevoured from the beginning to the end.Years afterwards, indeed, he gave proof ofhis knowledge of its contents by recitingthe substance of articles chosen at randomfrom it.

Victim of the GuillotineIn the midst of his placid and, perhaps,

somewhat pathological intellectualism astorm broke with elemental fury into

Ampere's life. It was the world-shakingstorm of the French Revolution. It wasan upheaval which carried away his father,Jean Jacques Ampere, to the then almostcontinuously operating guillotine of theRevolutionary Government in Paris, forAmpere pere had, in his retirement, beena juge de paix-in other words, a magis-trate-and, as such, a member of the much -hated " aristocrats."

The tragic fate of his kindly father broughta great sorrow into young Ampere's life.He endeavoured to drown it by assiduousstudy. He went for long excursions andbotanising expeditions, and it was on oneof these excursions that he met his firstwife, Julie Carron. After their engagementAmpere became a private tutor in Lyons,and not very long after his marriage heobtained. a lectureship in chemistry andphysics in a French county school. Aftera year or two Ampere was able to returnto Lyons, having obtained (in 1803) theprofessorship of mathematics and astronomyin the newly founded Lyceum in that city.

Less than a year afterwards his wife died.He then gave up his professorship at Lyonsand sought refuge from his sorrows in Paris,obtaining there a post of tutor in thePolytechnic School.

After a little while things improved forAmpere. He settled down to his studiesagain, devoting much time to mathematicsand building up his scientific reputationby the publication of original papers. In1806 he was appointed secretary of theFrench Bureau of Arts and Sciences. Andin that year, also, he married again.

A couple of years went by, after whichhe became an " Inspector -general " to theUniversity of Paris. In the following year(18o9) Ampere was" nominated to the Profes-sorship of Analytical Calculus and Mechanicsin the Polytechnic School at Paris.The Top of the Ladder

Ampere had now climbed almost to thetop of the academical ladder. He remainedin Paris for almost the rest of his life. Allhis researches, electrical and otherwise, werecarried out under the roof of the greatPolytechnic in Paris, and in the famedFrench Institute in that city.

From these seats of original learningAmpere published a large variety of scientificpapers on mathematics, physics, botany,natural history, chemistry and mechanics.The subject of electricity happened to bejust one of the many studies which he" took up," as it were, almost automatically.It was a study which appealed particularly

el needle or a nail placed across a wire carrying a current becomesmagnetised.

Residual magnetic influence in a nail which has been electro-magnetised,is sufficient to exert its effect upon a compass needle.


to the brain of Ampere on account of itsneed for mathematical treatment. Henceit was that his interest in electricity andmagnetism, and, afterwards in electro-magnetism, was mainly of a mathematicalnature.

Let it be said at once that Andre MarieAmpere was no painstaking, practical geniusin the electrical art as was, for example,our own renowned Michael Faraday.Indeed, Ampere failed to make any reallyfirst-class electrical discovery. Yet it washe who, by systematising and explaining thediscoveries of others, particularly the dis-covery of electro-magnetism which wasmade by Oersted in 1820, put electricalscience on its feet and made it possiblefor future workers to have a clear under-standing of the subject in which they wereengaged. The great Faraday, among manyother original workers, was indebted to themore theoretically minded Ampere for muchof the groundwork on which he based hismagnificent discoveries.

It was Oersted's discovery of electro-magnetism in 1820 which seems to haveimpelled Ampere in his Parisian laboratoriesto concentrate his attentions on electricalwork. Within a week of Oersted'sannouncement of his discovery, Ampere hadworked out an almost complete expositionof Oersted's electro-magnetic effect, andhad demonstrated that all magnetic effectscould be produced by the electric currentalone. Such a result of high-pressure workon the part of a single individual is almostincredible, but dates are dates, and anyonewho cares to examine the publication datesof Oersted's and Ampere's original paperswill be amply convinced of this fact.

Ampere's RuleAmpere gave a definite rule for finding

the direction in which a compass needleturns under the influence of an electriccurrent, this effect constituting Oersted'soriginal discovery of electro-magnetism.

Said Ampere: " Picture a little manikinswimming with the current while facingthe compass needle. The north pole of theneedle will then be turned to his left, whilethe south pole of the needle will be turnedto his right."

This imaginary " bonhomme d'Ampere,"as others quickly dubbed the electricalswimmer, has from Ampere's time beenparaded in nearly all electrical textbooksas an aid to the student in determining themovement of the magnetic needle in relationto the direction of the electrical current, or,conversely, as a rule for ascertaining thedirection of the current from the observationof the movement of the needle.

Ampere did more than this, however. Hewas the first to show that if electric currentsflow through two adjacent parallel wires,the wires will tend to attract each otherwhen their respective currents flow in thesame direction, but that the wires will tendto repel each other when their respectivecurrents flow in opposite directions. Heshoward that this force of attraction orrepulsion is directly proportional to theintensity or strength of the currents andinversely proportional to the square of thedistance between the wires.

Perhaps it was this particular discoverywhich James Clerk Maxwell had in mindwhen he first called Ampere the " Newtonof Electricity," for, the reader will remember,it was the great Sir Isaac Newton who firstannounced a similar law with respect to theforce of gravitation.

Discovery of the SolenoidIt was Ampere who introduced the

electrical " solenoid " and, afterwards, theelectro-magnet.

It is very interesting to trace the courseby which these two discoveries came about,since, unlike not a few other discoveries,they were by no means creations of chance.

Ampere, in thinking out an explanationof the electro-magnetic effect observed byOersted, postulated a theory whichendeavoured to account for the phenomenonof magnetism by supposing that the magneticeffect of, say, an ordinary bar magnet isdue to a tiny electric current which con-tinually circulates around each individualmolecule of iron in the magnet. In thenon-magnetic state these supposed molecularcurrents circulate around the molecules invarying directions, but when the bar ismagnetised the currents, according toAmpere's reasoning, must circulate in onedirection only. So that, in effect, the sumof these minute circulatory currents would

MercuryCups

Solenoid

\1/4

Showing Ampere's method of suspending afreely -movable solenoid from mercury cupsin order to demonstrate the solenoid's behaviouras a magnet when a current is passed through it.

be equivalent to that of a larger singlecurrent moving in a series of circles.

Ampere's theory of magnetism was wrong,but it led to surprising consequences,practical as well as theoretical. It resultedin Ampere's trying out the effect of a singleelectric current flowing in a circulatorymanner through a helix of wire. And, justas Ampere expected, under these conditions,the helix behaved, when freely suspended ormounted, just as if it were a bar magnet,the helix taking up a horizontal positionnorth and south just as a bar magnet woulddo when freely mounted.

Ampere's electrical helix came to beknown as a " solenoid," the word beingderived from the Greek and meaning" tubular." Solenoids attract and repel eachother, as Ampere discovered, according totheir polarities just as ordinary magnets do.Indeed, as Ampere remarked, they are tobe regarded as " skeleton magnets," or, aswe might say to -day, synthetic or artificialmagnets. And just as a bar magnet willcommunicate its magnetism to a non-magnetic iron bar, so; too, will a solenoidimpart its magnetism to a metal rod or barwhich is placed within it, but out of anydirect electrical contact with its coils.

Illustrating the outcomeof Ampere's solenoid-the electro-m agnet,comprising merely aniron bar placed within

a solenoid.

The Electro-magnetHere, of course, we have the electro-

magnet, the parent of countless electricaldevices. Whether the first electro-magnetwas made by Ampere or by his brilliantcontemporary Francois Arago, a Frenchphysicist and astronomer, seems to bedoubtful. It was certainly Arago (notAmpere, as has sometimes been stated) whofound that a conductor carrying a currentwould feebly attract and magnetise a needleor a nail placed across it, but it was Amperewho ascertained that the needle or nail might,under these conditions, sometimes becomesufficiently magnetised to exert an influenceon a suspended compass needle in just theSame way as an ordinary magnet is able toattract or repel the pole of a compassneedle.

It is fairly certain, however, that toAmpere goes the priority of reasoning thata coiled wire ought to intensify this effect,and of thus bringing into practical possi-bility not only the solenoid but also its directoutcome, the electro-magnet.

Based upon the idea of the electro-magnet,Ampere put forward the notion of an electrictelegraph. But he was nor practically mindedenough to get anywhere with this project.For instance, the telegraph which heproposed was to be based upon the deflectionof a magnetic needle by a wire coil carryinga current, tut there were to be as manyneedles, coils and connecting wires as thereare letters in the alphabet. And since, also,the chemical battery was the only sourceof the electric current in those days, verygreat battery power would have been neces-sary for the operation of such a telegraphover any reasonable distance. Hence thewhole notion of the telegraph as projectedby Ampere was dropped in favour of morepractical schemes which were not very longin forthcoming. All the same, sinceAmpere's telegraph plan was announced ina paper read by him before the FrenchAcademy of Sciences on October 2nd, 1820,its projector must, in fairness, be numberedamong the few claimants for the honourof being designated " Father of the ElectricTelegraph."

This was about as far as Andre MarieAmpere went in the science of electricity.He laid the foundations, cleared away amass of former misconceptions, andindicated where others might build. Buthe took little, if any, part in the subsequentwork of applying electrical science topractical ends.

Indeed,. Ampere's life at this period seemsto have become one entirely of routine. Hissalary was small and he had accustomedhimself to living in what used to be termed" gentile poverty." in many respects,Ampere, during the height of his fame,seems to have been the typical personifica-tion of the legendary absent-mindedprofessor. If we are to believe variousaccounts of his ways and habits he wouldoften, when lecturing to his students on ahot summer's day, mop his forehead withthe blackboard duster and immediately

September, 1946

afterwards proceed to wipe out the black-board figures with his silk handkerchief.

Ampere's EssaiAlmost his last creative work was

Ampere's Essai stir la Philosophie desSciences, a work which he did not live tocomplete but which was afterwards pub-lished in its incomplete form in 1838.Ampere's last Essai attempts to present thewhole range of science and natural know-ledge to the student. It begins by dividingscience into two large categories, materialscience and the science of mind or thought.Each of these two divisions was subdivided,and by this means more than a hundredbranches of natural science were obtained.

Some of Ampere's names for his arbitraryscience divisions sound fantastic to our ears.

NEWNES PRACTICAL MECHANICS 435

Who has ever heard of the sciences of" terpnognosy," " technesthetics," " coenol-bology," and " cybernetics," to mention buta few of the strange names in Ampere's lastEssai ?

The Essai is, indeed, a work of a lifetime'sintensive learning, and a tremendous tributeto the ingenuity of its author, but, all thessme, it is unbalanced, impracticable,unfinished, and, as such, has been forgottenfor three generations.

As he grew older Ampere's health becamefeebler, and the time eventually came whenhe had to leave Paris and to go south insearch of relief from his chronic chesttrouble. He went to Marseilles hoping thatthe gentle breezes of the Mediterraneanwould restore him at least partially. Buthe had no sooner got there than he was

seized with a brain -fever. It was his lastillness, from which he died on June Toth,1836.

The scientific world regretted Ampere'spassing. Although retiring, nervous, shy,and impracticable, Ampere had made agreat impression, through his original work,upon contemporary scientists and philoso-phers. They acknowledged his originality,if somewhat belatedly, and they raisedmonuments to him.

But the greatest monument of all camein 1881 when the International Congress ofElectricians met in Paris and agreed todesignate by the term " ampere " the unitof electrical quantity, thereby translatinginto living language the memory of a manwho had done so much to establish thefoundations of electrical science.

The Netherlands RailwaysOne Year After the Liberation

Only half a year after the total destruction of the Oosterbeek railway bridge, nearArnhem, the first train passed over the emergency bridge.

FOR seven long months, from September17th, 1944, to May 5th, 1945, thegreatest part of the railway system and

industry of Holland lay paralysed. Stationsand yards, roadbeds, signal -boxes and bridges,everywhere lifeless and deserted, fell easy preyto the fury of the enemy, whose rage atapproaching defeat was vented on the first-class equipment and installations of theNetherlands Railways. This destruction,carried out with typical German thoroughness,transformed the Netherlands Railways intolittle more than a mass of wreckage, so thaton the day of liberation it seemed that itsrestoration might well be despaired of.

Certainly the restoration has been no simpletask ; primarily because the most indispensablematerials have been unavailable. But regard-less of this the railway personnel set to workwith all their might and soon the first trainswere running again in Holland. To beginwith they carried food and displaced personscoming home, but before very long a passengerservice was possible.

Now a year has -gone by. A year ofgreat effort on the part of everyoneconnected with the railway, from highto low. A year in which almostinsurmountable obstacles had to beovercome ; in which problems hithertounknown were solved by most originalmethods. But all these difficultieshave been, as far as possible, over-come. The means were found, byimprovisation or experiment-whilenever for one minute forgetting thatsafety is the most important con-sideration-and bit by bit, mile bymile, bridge by bridge, the rebuildingof the railway went on.

Reconstruction PlansIt is still going on, at full speed.

The reconstruction is to only a smalldegree complete. But this seems tobe an appropriate time, just exactly ayear since the reconstruction could bebegun, to look back and see what has

been accomplished during this period. Thiscan be most clearly shown with the aid of afew figures.

In September, 1944, the NetherlandsRailways operated 1,974 miles of railroad,of which by May, 1945, 1,221 miles, or 62 percent., were destroyed or torn up. Now, ayear later, 1,800 miles of line, or 91 per cent.,are back in use. In September, 1944, therewere 354 miles of electric line. Of this 315miles, or 92 per cent., were destroyed orrendered useless. Now 115 miles are back inservice.

Once there were 21 railway bridges overthe great rivers. Sixteen of them, or 76 percent., were blown up or obstructed. Thanks to

The bridges of Holland, with its numerous rivers andcanals, are of supreme importance. Everybody inHolland knows this, and so did the Germans, and they

destroyed 7o per cent. of the railway bridges.

436

tremendous efforts and the great help givenby our Allies, 12 of the bridges, or 57 per cent.,are open to traffic again. In total, 220railway bridges were blown up or damaged.At present 191 of these are open to traffic again.

There is one more set of figures that gives aclear picture of the achievements of this year ;this shows the distances travelled by train.In September, 1944, 38,562 miles were runby passenger train and 24,375 miles byfreight. On May 5th, 1945, the total-thanksto the restoration of one line in the south ofthe country-amounted to 1,183 miles and1,313 miles respectively. Now, one yearafterwards, the distances travelled are :29,493 miles by passenger train and 20,625miles by freight, that is 68 per cent. and 85per cent. of the former totals.

Shortage of MaterialsThe greatest difficulty facing this work of

reconstruction is the general world-wideshortage of materials. This also accountsfor the less rosy picture given by some otherfigures. In September, 1944, there werealtogether 163,000 seats in the passenger carsof the Netherlands Railways. Of these nofewer than 156,000, or 96 per cent., are a totalloss, as the Germans removed or destroyed ahuge number of passenger trains. On top ofthis, the workshops, where much repair workmight be done, were plundered and wreckedso that only a limited amount of work can bedone in them even now. Thus it is that the


Netherlands Railways still only have some45,560 passenger seats, or 28 per cent. of theoriginal total.

Finally, some figures on the rolling stock ofthe Netherlands Railways. Naturally, thegreater part and the best part of this is stolenand gone. The 137 streamlined electric carsthat the Netherlands Railways still owned inSeptember, 1944, were all removed ordestroyed, as were the 57 Diesel; electric and25 Diesel cars, which were once the pride ofthe Netherlands Railways. Most of this stockwas removed eastwards and what has returned-and it is by a long way not all-is in amiserable condition. However, it has beenpossible, even in the sadly wrecked workshops,to repair some of these cars so that there areat present 31 streamlined electric, 14 Diesel-electric and to Diesel cars back in service.

Steam EnginesThe Germans attached great importance to

steam engines, which they showed by makingoff with or destroying 722, or 84 per cent., ofthe total of 866 belonging to the NetherlandsRailways. Some 400 of these were locatedin Germany and have been brought home.But that hardly means that they are fit for use ;some of them will never run again and theironly value is that they can give material for thereconstruction of others. However, a certainnumber can certainly be repaired, which workis being carried out, with the valuable co-operation of private firms as well, at the

September, 1946

Netherlands Railways workshops at Tilburg.At present there are 326 locomotives running,which is 37 per cent. of the number in use in1944, and this includes 15 new Swedish arid19 not new but perfectly serviceable Swissengines.

This question of locomotives poses a con-siderable problem in reorganisation of theservice of the Netherlands Railways. For,though it is true that the railways also havethe use of 294 engines hired from England,these are not in good repair and, despite thefact that private firms are joining in the repairwork, it is hardly possible at one and the sametime to rebuild the damaged engines and keepthose now in use in repair. The result of thissituation is that the supply of locomotivesremains limited, while the work of re-construction cannot expand.

Shortage of CarsAn additional difficulty is the shortage of

cars for steam -powered engines. Before thestrike there were 1,498 cars, of which 1,406,that is 94 per cent, of the total, are gone.At present the Netherlands Railways have nomore than 466, or 31 per cent., cars which,in addition to the 232 loaned from abroad, isstill too few. It is for this reason that theNetherlands Railways have been forced to usefreight and baggage cars for its passengerservice.

But that all of these difficulties will be over-come, there is no question.

Scientific FactsBy Prof. A.

Air Is Mighty HardT HAVE often explained that hardness

depends entirely on speed and that ifyou slap your hand on a basin of water itwill sting because the water is hard at highspeeds. You can assure yourself and yourfriends by demonstrating the hardness, as itwere, of air at high speeds, or at least thepressure of air in the atmosphere againstwhich a car has to push its way.

On a smooth table, hanging over one edge,place a thin board about t8in. long by loin.wide. Open a newspaper and put two or threesheets over the half of the board which restsupon the table. You have positively " nailed "the board to the table and if you give theoverhanging part a really hard blow with yourfist you will find that nothing happens.

It is a matter of time, because the paperprevents the air getting under the boardduring the period of your blow. Press slowlywith your little finger on the overhanging partand up she comes without a tremor.

Any pilot will tell you that to open yourmouth at 200 m.p.h. in an open 'plane wouldbe very stupid and if you try to hold out yourhand from an aeroplane cockpit the air athigh speeds is so hard that it knocks it backas if it had been hit by a brick.

I once saw air escaping from a pressurechamber at about 5,000lb. per square inch.Hammers and spanners and half bricksbounced on the stream exactly like the ping-pong balls which dance on a thin water jetat a shooting gallery. So you must think ofthis factor of speed. Engineers always do.When gas has to travel fast in a pipe theycalculate the bends as if they were dealingwith treacle and not air. Air in inlet pipescompresses, gets hot and bounces about likea lot of springs. The watching eye of a high-speed cinema has got to have a butterflyon the wheel effect, the picture itself travellingwith everything that moves.You Can See By ItWHEN writing about light I think I did

not make it clear that what you and I

M. LOW

call light is only one form of an etherialoscillation. It mildly resembles wirelesswaves except that its frequency is vastlyhigher. Grey light from the sky is a combina-tion of all the spectrum colours and if youpaint a white disc about Sin. diameterwith segments of each of these rainbow coloursand then spin it like a top you will soon findthat the colours blend into white. There aremany other kinds of light, each differentfrom its neighbour. There is the cathode-raywhich makes some of the platinum compoundsfluoresce, a property very useful to makers oftelevision screens. X-rays are also light, buthave quite different properties, and arecapable of penetrating apparently opaquesubstances owing to their very short wave-length with which the particles .of normallysolid matter are liable to interfere. If youhad eyes which were sensitive to X-raysyou would be able to see through walls ;if you had eyes like a microscope you wouldsee the air full of living creatures, and if itdid not happen that the sun's rays werecomposed mainly of these spectrum coloursyou would never have taken white to be plainand not coloured. If the sun's rays had beengreen your relative eye sensibility wouldhave been different for you are a creature ofevolution in nature's plan. You would havelooked at a pair of bright red pants andremarked " what a pity they are not coloured."While white would, no doubt, have seemedmost glaring and out of place. Heat is merelya slightly different form of light with a longerwavelength. It can be focused as in thenormal electric fire, and its rays can be bentlike those of light by using the proper material.In the early days of infra -red photographywhen it was first discovered that photographscould be taken through cloud the first experi-ments were made with lenses constructedof rock salt because this substance did notcut out the heat rays. There is no realdifficulty in taking a photograph inside a darkroom by the light of a kettle of hot water.

At the other end of the stick we haveultra -violet light, which is invisible, and

which does not pass through lenses containinglead. That is, of course, why special glasshas to be employed if the full benefit ofthe sun's rays is to come into your house.In this world we know very little about light,but we do know that it is a somewhat materialthing, and I quite think that when atomicpower has been further investigated and wehave found how to change matter into energyquite easily, we shall be able to writeknowledgeably about the weight of light.For light has weight, and actually hits us allthe time. It has been calculated that if a half-penny was raised to the temperature of theinside of the suh the actual weight of light pro-ceeding from it would knock down everyoneto a radius of over five miles. Obviously, itwould frizzle them up first, but in these war-like days that is probably not so interesting.

Floating MetalDURING the war, and at the height of

London's bombing, I was engaged ontoying with explosives in an area round whichburning houses enabled the reading of anewspaper in the middle of the night to becomfortably practicable. So you will under-stand that the anti-aircraft defences wereof some interest to me.

A friend came along with the suggestionthat if we could fill small cylinders a fewfeet long and a few inches in diameter withhydrogen, releasing them in millions, theywould prove definitely unpleasant to enemypilots.

He did not realise, of course, that toachieve such an object the aluminium wouldhave to be so thin that it could never be usedin practice.

Yet one can understand that without alittle arithmetic he could easily go wrong,for the gasbag of the original Zeppelin wasconstructed entirely from sheets of aluminium.The volume of gas contained in this waywas far greater in proportion to its weightthan could ever be arranged with smallcontainers.

No aluminium could be made sufficientlythin to render the use of hydrogen -filledwalking sticks of any purpose although Ishould mention that metals can be so thinthat light is often transmissible. The resultingcolours and interference with light waveswhich result arc surprisingly beautiful.


Radar Aids the Weather ForecasterA Brief Outline of the Developments Made in this Important Branch of Science

IT has been found that radar of the shorterwavelengths can see areas of rain, fallingsnow, and certain types of cloud that

are dangerous to 'planes, in addition todetecting targets such as ships and aircraft.

The echo obtained from these weatherphenomena is easily distinguishable, beingspread out over the radar screen, consequentupon the large area covered by the " target,"whereas the echoes obtained from shipsand aircraft are very precise.

By watching _the motion of these weatherechoes across the screen the speed with whicha rain belt, or a thunderstorm, is moving canbe accurately calculated ; so that from theinformation of its exact position given bythe radar, it is possible to forecast to withintime limits of two or three minutes whenthe rain will reach a given place.

Furthermore the brightness of the echoindicates the intensity of the rain, thus theweather forecaster is able to say whetherapproaching rain is becoming lighter orheavier.

Advanced TechniqueWith the type of radar set at present in use

for this work, one is able to watch the weatherover the area within a hundred miles radiusof the set. As a rain belt rarely moves acrossthe land, or sea, with a speed of more than20 m.p.h., use of radar to forecast its arrivalshould enable nearly five hours' accurate warn-ing to be given. Unfortunately thunderstormsare a somewhat different proposition, as theygenerally develop rapidly, and the radaroperator will see the echo of the stormsuddenly appear on the screen as the thunder-cloud reaches an optimum state in its develop-ment. It is, however, found possible to givea 55 minutes' warning of the approach of athunderstorm.

As may be imagined, the use of thistechnique in weather forecasting is a greatadvance on previous methods, when thetime limits of predicting the arrival of abelt of rain were within the regions of anhour, and as far as thunderstorms wereconcerned it was only possible to state thatthey could be expected over a large area,and no warning at all could be given to theplaces subjected to a downpour.

Besides seeing rain, radar can detect fallingsnow. This gives a less intense or brightecho than a steady fall of rain so that thereis a danger that by merely using radarobservations it may be difficult or impossibleto distinguish between light rain and heavysnow. This, however, is no great problemas the weather forecaster can state definitelyfrom the information normally available tohim which of rain or snow is to be expected.

An interesting phenomena is that meltingsnow gives a far brighter echo on the radarscreen than the rain which it eventuallybecomes. Meteorologists believe that in thiscountry all rain commences to fall as snow,so that by directing a radar beam up intofalling rain, a very bright echo will be obtainedfrom the melting snow flakes at the freezinglevel of the atmosphere ; thus enabling theheight of the level to be measured. Thisprovides a valuable aid to meteorologists, asa knowledge of the height of the freezinglevel is of vital importance when forecastingicing conditions for aircraft-a matter ofgrave concern to pilots.

Another danger to aircraft is the type ofcloud in which there are large verticalupcurrents. These currents frequently attainvelocities of over zo m.p.h., so that the

By E. L. WILLEY,

strongest aircraft is soon broken up if ithappens to enter one of these clouds. For-tunately such clouds may be detected byradar, so that the pilot of an aircraft needhave no fear of such clouds in the dark, ifhis craft is equipped with suitable radar.

The radio sonde meteorological balloon readyfor release. A small parachute is tied belowthe balloon which expands as it rises into therarefied upper air. In the stratosphere, at aheight of ten miles or more, the balloon bursts,and the apparatus floats down on the parachute.

Value to IndustryIt thus appears certain that the use of

radar for watching the weather will prove ofimmense value to industry, commerce, andshipping. Power supplies may be put out ofaction over a wide area by a heavy thunder-storm, a failure which can be averted if thepower company has a 55 minutes' warningof the deluge.

Radar in aircraft may be used to warn thepilot of dangerous clouds and areas of badweather that lay on the course of the aircraft,and the weather information obtained from aset at an airport can be used to guide incomingaircraft so that they avoid areas of badweather and dangerous clouds. Also theaccurate forecasts possible as to the weatherconditions at the airport will prove ofinvaluable assistance to the flying controlauthorities in planning the various alterationsto flying schedules which the weather makesnecessary.

In the tropics the impossibility of accuratelytracking typhoons has seriously impaired theaccurate forecasting of their movements, adifficulty which the use of radar will to aconsiderable extent obviate.

The weather forecaster at sea will findradar an invaluable assistant. Even in peace-time, weather observations over the seaare sparse, a fact which makes forecastingat sea a difficult task. Now with the aid ofradar, the sea -going meteorologist is able towatch the weather for a hundred milesround his ship and as a result is able toforecast with the same facility as his colleagueashore.Wind Speeds

An important feature of a weather forecastis the speed and direction of the wind up toheights of to,000 to 15,000 ft. A knowledgeof these is essential for the navigation ofaircraft, and in wartime for accurate gunnery.The meteorologist normally finds these windsby observing at given time intervals thehearing and elevation of a hydrogen -filledballoon, rising at a predetermined rate ofascent. Then by the use of simple trigono-metry he calculates the wind speeds anddirections at the various heights. Thepresence of low cloud, in which the balloonsoon becomes lost, more often than notbrings such observations to a premature end.A rubber meteorological balloon, in itself,gives no echo on a radar set, but now anumber of types of radar targets for attach-ment to these balloons have been developed,so that they can be tracked by radar throughoutthe course of their ascent.

As a result the winds at high levels may befound in good or bad weather, by night orby day.

All the developments outlined in thissurvey have been produced as a weapon intime of war, but now we may look forwardto the use of radar in weather forecasting asan invaluable help in time of peace.

At Pasadena, California, Glena Bassett examines the ionisphere rocket, developed by the CaliforniaInstitute of Technology, that set an American altitude record of 230,000ft. in a recent test.


THE WORLD OF MODELSBy "MOTILUS"

A Realistic Model Railway, and a Gloucester Man's Model Ship Built from MatchesTHE model railway which forms the

basis of this article is the property ofan architect, Mr. H. Linley Bown, of

Grain Beck, Killinghall, near Harrogate. Itis seldom that such a complete and detailedlayout comes up for sale, particularly at atime when model railways are still at apremium, but the circumstances of war havetaken away the boy for whom the railway wasbuilt and it is natural that his father will notnow have the same interest in their mutualhobby.

Electrically OperatedMr. Bown tells me it is getting on for

zo years since the first electric railway waspurchased for his son. It was an electrictrain of German make, purchased as a birthdaypresent, and it worked direct from the mainssupply through a resistance coil and carbonlamps. But after he had suffered one or twoshocks whilst operating this layout, Mr.Linley Bown decided it was not very safe for

the lad to work himself and the idea came tohim to build a model railway, using scalemodel track, rectifier and control, togetherwith locomotives, rolling stock and all generalequipment.

Being an architect it was not difficult forhim to draw out a detailed plan of his layoutand he sent this to Bassett-Lowke, Ltd.,asking them to supply all the materialsrequired. Apart from getting a joiner tomake the table, Mr. Bown built the entirerailway himself and did all the wiring forpower and lighting with the exception of theconnection from main supply to rectifier andthe fixing of main switch and fuses. He did,however, have occasional help from anelectrician for connecting up to control andthe electro-mechanical point operating device.

At the week -ends and in his spare time he

worked away at the layout, and it took himabout 18 months to build. The cutting andthreading of the point rodding and connectingto the bell cranks for operating points andsignals took perhaps the longest, especiallygetting the adjustment to give the necessarythrow for points, but railways had always

Two views of Mr.Linley Borvn'smodel railway.(Above) R ug byStation in theforeground. (Left)The main line andgoods sidings.York station is seenin the background.

been of great interest to him, and ever sincehe was a boy he had had the desire to constructa working layout.

The gauge of the railway is the standardgauge 0 (Win.), and the total length ofthe main double line track is 34ft. Thereare also five sidings accounting for another

25ft., making a total of nearly 6oft. in all.The main supply of electricity is 23o voltsA.C., transformed through a rectifier andreduced to 6-8 volts D.C. A vertical patterncontrol switch is used for starting, stoppingand reversing, and this is also fitted withterminals for use with two road railways.

Locomotive StudThere is an interesting locomotive stud-a

Princess Elizabeth passenger locomotive, astandard tank locomotive, the famousL.N.E.R. Flyinq Scotsman, and three2-6-0 types, G.W.R., L.M.S. and L.N.E.R.-and his rolling stock includes three passengercoaches electrically lit and one mail van withpick-up apparatus. His goods rolling stockis all in wood and comprises brake vans,covered wagons, open wagons, timber, brick

A close-up view of York Station.


Passenger and goods trains passing through York station.

and Colas wagons, and these are all fittedwith automatic _couplings, with a device forfly -shunting in addition.

The track is laid in scale model permanentway and has two signal boxes, each of whichcontains six lever frames operating thesignals and the points. Both the stations arelighted by electricity and, in addition, thereis one set of electro-mechanically operatedpoints. Other items in the layout are twoengine sheds, a turntable, a goods depot, acoal office, a platelayers' hut, a water towerand a loading gauge. Mr. Bown has notattempted to make elaborate scenery but hasobtained an excellent effect by cut-outsilhouettes of impressionistic style round thewalls. Realism is also achieved by the ampleattention to detail in the platform accessories-the numerous model railway station staff,the pillar boxes, trolleys, seats, bookstalls,telegraph posts and wires, and electric lightstandards on sidings make the railway live.The track is all ballasted, and the embank-ment is carried out in plaster of paris, colouredup and with trees and shrubs fixed in, eventhe addition of swans and a bridge to lend anout -of -the -ordinary touch.

Mr. Bown's boy joined the Forces in 1939and did not come back, but he has neverregretted the work he put into this railway.His son spent nearly all his spare time inrunning it, setting himself problems ofshunting and assembly of goods trains, time-tables for his passenger trains and in demon-strating to his friends, and during the waryears Mr. Bown himself has given displaysto the children in the village and to friendsand their sons, to whom the railway must havegiven in all hundreds of hours of enjoyment.

To run two trains, work the signals andpoints and do any shunting required, demandsconcentration to avoid accidents and in Mr.Bown's opinion helps to train a boy to thinkquickly, and the assembly of goods trainsin a pre -arranged order entails study andcalculation, helping to inculcate a sense ofresponsibility and carefulness in the buddingmodel engineer.

Here is an opportunity for someone else'sson. If the railway has not been disposed ofby the time this article appears in print,Mr. Bown would be willing to sell it complete,but the would-be purchaser must give anundertaking to arrange for dismantling andtransport. The table on which the railwayis built is made up in four sections and couldbe taken apart without removing the per-manent way, stations, tunnels, sheds, etc., asthe lines, point rodding, wiring and so forthcould be disconnected at the ends of- eachsection.

Model Cargo LinerNow from model railways to boats. I have

recently come across a very interesting modelcargo liner built by Mr. William Brain, of

Gloucester. It is sft. gin. long by min. wide,and is estimated to contain nearly 33,000matches.

Prior to 1941, Mr. Brain, who is nowemployed by the L.M.S. Railway Company,had been connected with the sea for over3o years and had served in the MerchantNavy. His hobby of ships dates from the timehe was at sea and he has constructed numerousother models. His latest model was built by,arrangement with the L.M.S. Home Guard,and waste matches have been sent to himfrom the goods station, while neighbourshave also helped to keep him supplied.

Working on this model in his spare time,Mr. Brain has taken about three months tobuild the ship, which weighs 121b. 20Z. Heused ordinary glue to stick the matchestogether and then painted the finished model.

His latest effort is to build a model of theL.M.S. Railway Company's motor vesselPrincess Victoria, which when completedwill be given to the Railway ServantsOrphanage.

Model Making in SwitzerlandThe writer has recently returned from a

visit to Switzerland for the first time sincethe Swiss National exhibition of 1939, and willhave a mass of interesting information onthe progress of model -making in Switzerlandduring the last seven years for our next issue.

Mr. William Brain and his model cargo liner.

Pegasus Engines in B.O.A.C, Flying -boatsTHE B.O.A.C. Hythe-class flying -boat

Hudson took off from PooleHarbour, Dorset, on the morning of

Sunday, May 12th, to re -open the Empireflying -boat route to Sydney, suspendedduring the war. Fitted to the Hudson,as to all other aircraft of the Hythe class,are Bristol Pegasus 38 engines, developing1,030 b.h.p. at take -off and driving deHavilland three -blade airscrews.

The Pegasus has had one of the longestand most remarkable records in the whole ofaero-engine history. First produced in 1932,the Pegasus initially developed 570 b.h.p.To -day it gives over i,000 b.h.p for the samecapacity. Four world height records werecaptured by Pegasus-engined aircraft in theyears before the war. The first was in 1932,when a Pegasus-engined Vickers Vespareached 43,976ft. The second and fourthflights, in 1936, and 1937, were made bySquadron Leader F. R. D. Swain and FlightLieutenant M. J. Adam respectively in Bristol

138A monoplanes in which the Pegasusengines was fitted with a two -stage super-charger. Adam's flight recaptured the recordfor Britain after it had been won by Italy-with a Pegasus-engined Caproni aircraft.

In 1938 Pegasus engines gained anotherhonour when they powered the VickersWellesley aircraft of the R.A.F. Long RangeDevelopment Flight, which beat the world'slong-distance non-stop flight record.

That the Pegasus was not merely an enginefitted for special record -breaking operationshas been proved by its reliable and efficientservice in military aircraft during the warand in civil aircraft both before and after thewar. With this engine, the Hythe-class flying -boats operate at 170 m.p.h. T.A.S. on 6oper cent. of take -off power.

Now the Pegasus is back on its pre-war job,for it was with Pegasus-engined flying -boatsthat the service to Sydney was inauguratedand maintained before the war.

ir

440 NEV/NES PRACTICAL MECHANICS

QUERIESa,,,,dENQUIRIESA stamped addressed envelope, three pennystamps, and the query coupon from the currentissue, which appears on back of cover, must beenclosed with every letter containing a query.Every query and drawing which is sent mustbear the name and address of the reader.Send your queries to the Editor, PRACTICALMECHANICS, Geo. Newnes, Ltd., Tower House,

Southampton Street, Strand, London, W.C.2.

Gold-plating BathIWISH to set up a small electro-gilding bathA for gilding some small articles.

Please let me have the formula for making thegold solution (t pint). Also the voltage to useand current density per sq. ft. of surface.-N.,Tibbitts (Gloucester).,THE simplest and the best way for any inexperienced

Person to set up a gold-plating bath is to purchaseready made a quantity of gold-plating salts from afirm of specialists in plating materials, such as Messrs.

.Wm. Canning and Co., Ltd., Great Hampton Street,Birmingham.

tt, If you wish to make your own solution, proceed asfollows :g Dissolve a quantity of fine gold (i.e., pure gold) ina mixture of 3 parts hydrochloric acid and t part nitricacid. After the gold has dissolved, evaporate thesolution to dryness. Then dissolve the residue in alittle distilled water and add to the resulting solutionstrong ammonia drop by drop until there is no furtherprecipitate.

The precipitate so obtained consists of gold fulminate.It is quite safe as long as it is wet or moist, but inthe dry state it is a highly dangerous detonatingsubstance. Hence, you must never allow it to becomedry.

Make up the following bath :Potassium cyanide .. to grams.Sodium carbonate .. 15 grams.Water .. 500 ccs.

This solution should have about 2 grams of the goldfulminate dissolved in it, although the exact quantityof the fulminate is immaterial. Use an E.M.F. of three -'quarters of a volt and use the bath at a temperature of6o deg. C. to get a full gold colouration. At lowertemperatures the gold is'deposited in a paler shade.

As an anode, you can use a piece of pure gold wireor, alternatively, a length of platinum wire. If you usethe platinum anode you will have to make additions ofgold fulminate to the bath from time to time in orderto make up for its loss in strength, the platinum anodenot dissolving in the bath.

It is, however, our opinion that, unless you arepractised in the art of gold-plating, you would be welladvised to buy your gold salts ready made.

`,.` Paste" Stones and ,jewelleryCAN you please tell me how paste stones 'and

jewellery are made ?-K. Beall (Sutton).THE term " paste " used in connection with

jewellery refers to varieties of glass which arecoloured by admixture of traces of certain metals.These special glasses have a brilliant appearance, inconsequence of which they serve extensively as gemstones.I- Here, for instance, is a " paste " for making imitationdiamonds :

Pure white sand, too parts (by weight) ; lead oxide,35 parts ; potash, 25 parts ; borax, to parts ; man-ganese dioxide, 5 parts. The ingredients are very finelypowdered and then heated in a furnace to white heat,at which temperature they fuse and form a variety ofglass which is afterwards made into " paste ' orimitation diamonds.

Electric Arc Furnace : lin. Spark CoilCAN you advise me concerning the voltages

necessary for an electric muffle andi anelectric arc furnace. I wish to run them off A.C.mains, so could you please specify what kind of atransformer and also any other requirementsthat I shall need ? Where can I obtain the partsfor the furnaces ?

I am in the process of making an inductioncoil to produce a spark of at least tin. from12 volts. Could you give me particulars of length,etc., of the wires for both primary and secondarycoils ?-B. A. Rimmer (Catterick).

N electric arc furnace can be supplied through aAsingle-phase air-cooled transformer from the

A.C. mains. For -lin. carbons you could use a trans-former having an output of about 20 amps. at 55 volts(x.t kVA.). A choke coil or series resistance should beconnected between the secondary of the transformerand the electrode.

You may be able to obtain suitable muffles fromThe Thermal Syndicate, Ltd., Walisend, North-umberland ; and Newtempheit insulating material

from Newalls Insulation Co., Broxbournbury,Broxbourne.

For a tin. spark coil fed from about t2 volts D.C.you could use a core built of 22 s.w.g. annealed charcoaliron wires built up to tin. diameter by 91in. long. Thecoil bobbin could be 81in. long between cheeks of27,in. diameter. The primary could have two layersof t8 s.w.g. D.S.C. wire, and the secondary lb. of38 s.w.g. D.S.C. The secondary layers should beabout a halt' shorter than the primary layers. Whenwinding the secondary the wire should be passedthrough a bath of hot paraffin wax, the surplus waxbeing wiped off with a piece of old linen whilst feedingthe wire on to the bobbin. A layer of thin papershould be wound between each of the secondary layers.The complete coil should be well basted with hot wax.A condenser should be connected across the make -and -break contacts. This could be made with too sheets oftinfoil, Tin. by 5in., interleaved with sheets of waxedpaper Bin. by 6in.

Field Winding for a Small MotorIHAVE a small electric motor (voltage 230-250),A the armature and field stamping of which areshown in the accompanying diagrams. I intendto use it for driving a cinema projector, or smallemery wheel. The field windings are burnt out,

I/ Commutator Segments

Clearance Between Armature & Poles 0.020'Armature and field stamping for a small

electric motor. (G. Webb.)

and I shall be glad if you will inform me howmany turns and what gauge of wire to use forrewinding the field coils.-G. Webb (Woodley).IN view of the fact that the number of turns and size

of wire on the armature are unknown, it is onlypossible for us to give you an approximate specificationfor field windings. We suggest you wind each fieldpole with 45o turns of 28 s.w.g. enamelled wire, thetwo field coils being connected in series with eachother, so the poles have opposite magnetic polarityand in series with the armature.

The speed of the motor will vary considerably withthe load, which makes the machine not very suitablefor driving an emery wheel, as the motor may run veryfast when unloaded. A switch should, therefore, befitted near the motor so this can readily be switchedoff at the end of the cutting period.

Solid 3tercuryT REQUIRE some solid mercury for experi-

mental purposes. By what simple methodwould you suggest I freeze the metal ?-O. Davies(Treorchy).

MERCURYfreezes at a temperature of -39 deg. C.

( -38.85 deg. C., to be exact), so that you willhave to cool the metal down to about --40 deg. C. ormore before you can obtain it in solid form.

September, 1946

A mixture of 2 parts of crystallised calcium chlorideand a part of powdered ice will lower the temperatureto about --40 deg. C., so that this freezing -mixturewill-theoretically-suffice. Yet, practically, it is notefficient. Your best plan is to use either Dricold,"which is solidified carbon -dioxide gas and which is(normally) obtainable from Imperial ChemicalIndustries, Millbank, London, S.W.t, or, better still,by the use of liquid air, which is a commercial, trans-portable commodity obtainable from The BritishOxygen Co., Ltd., Wembley (through one of its nearestlocal branches). A quart of liquid air (costing about6s.) would freeze pounds of metallic mercury and keepit in solid condition for days without in any wayaffecting it chemically.

Oil StainT DESIRE to make up small quantities of oil -

stain for use on woodwork, and should bepleased to receive your guidance as to the formulaand manufacturers of the materials required.-V. D. Armstrong (Birmingham).ALL you need for your purpose if a supply of

linseed oil and a quantity of oil -soluble dye,both of which commodities can be obtained from anylarge paint stores. Alternatively, the oil -soluble dyescan be obtained from any chemical manufacturer orwholesaler, such as Messrs. Philip Harris & Co., Ltd.,of Birmingham, or Messrs. A. Boake, Roberts & Co.,Ltd., Stratford, London, E.15.

Dissolve about to parts of dye in qo parts of linseedoil so as to give a to per cent. solution of dye in oil.If darker or lighter shades are required, vary theseproportions accordingly.

The stain is merely rubbed or brushed on to thewoodwork and subsequently allowed to " dry in."

Magnifying Power of TelescoperOULD you please let me know whether-, there is any method of determining themagnification power of a refracting telescopewithout special apparatus, and, if so, what it is ?

I am also mystified by the markings onbinoculars such as, for example, 6 30, andwould be much obliged if you would explainthis also.-S. Hadden (Nottingham).THE magnifying power of a telescope is governed

by the focal length of the object glass and by themagnifying power of the eyepiece. The longer thefocal length of the object glass and the greater theeyepiece power, the greater will be the magnificationof the instrument as a whole.

To determine the focal length of the object glass,remove it from the barrel of the telescope and hold itin the sun's rays so that an image of the sun is thrownon to a sheet of white paper. Move the glass backwardsand forwards in front of the paper. At one positionof the glass, the circle of light (i.e., the sun's image)thrown on the paper will be the sharpest. Measure,now, the distance from the centre of the object glass tothe paper. This will give you the focal length of thelens. The focal length of the eyepiece can be estimatedin the same manner, but the eyepiece focus or focallength will be in inches, whereas that of the objectglass will usually be in feet.

Strictly speaking, the business of the object glass isnot to magnify. It is merely to form an image of theobject looked at, this image then being magnified bythe eyepiece glass. Hence, the greater the focallength of the object glass and the greater the magni-fication of the eyepiece, the greater will be the degree ofmagnification of the telescope system as a whole.

The same principle applies to binoculars. Thesmaller numeral refers to the object glass magnification,the larger numeral referring to the diameter (inmillimetres) of the object glasses. The greater theobject glass diameter, the more light it admits and themore brilliant is the image. The greater the eyepiecemagnification the greater is the apparent nearness ofthe object looked at.

The Composition of AlabasterIWISH to knew if alabaster is a compositionA substance, and whether or not it is a patentedformulae ? Also, how is it made and coloured ?-A. Charlton (York).ALABASTER is not an artificially made substance.

It is a naturally occureing mineral. It is a soft,semi -translucent material composed of calciumsulphate with a little calcium carbonate, together witha little iron, which gives it veins of yellow and brown

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and sometimes red. It used to be mined chiefly inItaly.

A so-called imitation of alabaster is said to be madeby colouring plaster of Paris with a little ochre, butthis material is brittle and not satisfactory. There is,in fact, no satisfactory imitation of the real material.

Water AnalysisCAN- you tell me whether there is a chemical

formula dhereby one is able to deter-mine the purity of water so that it may be safefor drinking purposes ? I wish to experimentwith several samples of water, and to find outwhat foreign matter or pollution they contain.-G. Tanner (London, S.W.).THERE is no simple chemical or chemical formulx

which will enable you to determine the purityof water for drinking purposes.

Water analysis is, at the simplest, a complicatedmatter, even when non -drinking waters are concerned.When drinking waters are involved, not only chemicalanalysis, but also bacteriological examination is essential,since a water may be fairly pure chemically butcontaminated bacteriologically, and vice versa.

What you require is a good modern book on waterexamination and water testing, such as one of thefollowing :

W. P. Mason : Examination of Water : Chemicaland Bacteriological (r8s. net) ; J. C. Thresh andJ. F. Beal : Simple Method of Water Analysis (35.net).

We believe, also, that Sofnol, Ltd., Greenwich, issuea useful booklet on water -testing, and we think thatthey would let you have a free copy if you would writeto them on this matter. Otherwise, your only modeof becoming expert in water examination is to study agood textbook and to make experiments as you progressin the subject. A good working knowledge of normalchemistry is, of course, also essential.

Welding GlassesWOULD you please let me know the best way to

keep welding glasses clear in hot weather ?Also, I would like to know what colour of glass isbest for these glasses or goggles when used forlight work, such as the mudwings of motor -cars.-J. G. Huggins (Enniskillen).MAKE up a stiff paste by squeezing together shredded

soap and glycerine. Smear a thin film of thisover- the glasses. It will help to keep them free frommoisture condensation.

A dark green or greenish -blue glass is probably thebest for the work you name, although the pure blueglasses supplied with many welding outfits are quitesuitable. Light blue glasses and those which are merelytinted should not, of course, be used, since they do notkeep back the intensely powerful rays which areinjurious to the eyes.

Aquarium Water TestingPOULD you give me any information on- aquarium pH or hydrogen ion water testingsets ; if they could be made, or where I couldbuy one ?-J. Thompson (Southfields).AQUARIUM water pH testing sets comprise

a series of tubes containing coloured liquids,each liquid having a definite pH value (or hydrogen ionconcentration). A few drops of the water to be tested areplaced in an empty tube of similar size to the specimentubes and a drop of coloured " indicating ' liquidis added to the water under test. The resultingcolouration is then compared with the series of specimentubes and the precise pH value is thus readily estimatedby this comparative method.

These pH value testing sets for aquarium water canbe obtained through any of the big London dealers inaquarium supplies and requisites, or, direct, from TheBritish Drughouses, Ltd., Graham Street, City Road,London, N.I.

Renovating a Chipped Bath'THE enamel on my, bath has chipped away

exposing large black patches. I should liketo re -enamel it, and shall be glad if you couldprovide me with a simple formula and method.If this is not possible, what other action can Itake to make it fit for use ?-J. Marco (Leicester).YOU do not say whether your bath is one of the

porcelain :enamel type or whether it is merely aniron bath which has been given one or two coats ofa white enamel paint. In the latter case, the remedy issimple, consisting merely of smoothing the sides of thedefective area and in re -painting the bath.

If, however, the bath is a " porcelain " one, that isto say if it has an iron base which has been vitreousenamelled, there is, unfortunately, no remedy for thetrouble which you yourself can apply. The vitreousenamelling of the bath is effected by painting the bathwith a special enamel and by afterwards Subjecting itto white heat in a specially -designed furnace wherebythe constituents of the enamel melt and fuse togetherto form a glass -like surface which is rendered opaqueand coloured by the white pigment in the enamel.You cannot possibly imitate this process yourself evenon the smallest scale, and it would be an exceedinglyexpensive job to have the bath re -enamelled by thevitreous enamelling process. Thus, so far as we can see,the only move which you can make is to buy fromyour local paint store a small quantity of some reallygood white enamel paint, and, after smoothingdown the edges of the defective area of the bath, toapply several coats of the white enamel paint, therebygradually building up an enduring white coating over theunderlying black patches. This treatment, to a large

extent, will hide the disfigurement, but, naturallyenough, the enamel paint will not be anything like asenduring as the normal vitreous or " burnt -on "enamel of the bath. But in this matter, it is, we areafraid, a case of Hobson's choice.

Etching on CelluloidT SHALL be glad of any information of methodsA of etching on celluloid. It is required to formclear lines which will be filled with a suitableblack. Can you suggest such a black ?-T. A.Locke (Newquay).THERE is no satisfactory chemical method of etchingA on celluloid. Liquids which attack celluloid,

such as acetone -amyl acetate mixtures not only dissolvethe celluloid exposed to their action but they alsosoften the surrounding parts. Hence, by treating thecelluloid with such liquids you would not get clearlines.

Celluloid can, of course, be embossed by means ofheated stamps, and its surface may also be lined by meansof an electro-engraving stylus. For filling the lines,use a stiff black ink made by working lampblack intobeeswax which has been softened by a- mixture withraw linseed oil.

For actual surface writing on celluloid in black, usethe following ink :

A. Tannic acid .. 5 grams.Acetone .. 25 c.cs.

13. Ferric chloride .. 5 grams.Acetone .. 25 c.cs.

Mix A and B together to produce the black ink, andstore it in a bottle provided with a well -fitting stopper.This ink attacks celluloid, and probably it might be ofsome use for your especial purpose.

Windings for a " Growler"T ENCLOSE a drawing (Fig. a) of an assembled

" Growler " which is usccl for testing smallD.C. armatures for short-circuits. From thedimensions given, can you tell me how manyturns I shall have to put on the coil and also the

Movable JawsBrass Clamp

, 0( c

8

Core A 26x7"

Coil

by diverter control. We may be able to suggest suitableresistances for such a motor if you will let us know thepresent speed on full load, the speeds required, andpreferably the voltage drop across the field coils onfull load. Resistance control will result in rather a bigvariation of motor speed on a varying load.

Removing Stove EnamelT WISH to construct a tank for the purpose of

removing paint, particularly stove enamelfrom bicycles. Would you please oblige by givingdetails of : a. Composition of bath ; a. Formulaof liquid.-G. C. Rink (Birkenhead).TZEAL stove enamels are very difficult to remove.Ix The cheapest medium for dealing with suchenamels is a strong, hot solution of Soda ash or causticsoda.

Alternatively, the following composition has beenrecommended for removing enamels :

Benzene .. 5o parts (by weight)Methylated spirit .. 25Acetone .. soNitric acid .. . so 92

Turkey Red Oil 5Beeswax .. rA simpler solution of this type can be made by

dissolving 3o parts of paraffin wax in 500 parts of benzeneand then adding soo parts of acetone. This is veryhighly inflammable. It is best brushed on to the enamel,'allowed to remain on for five minutes or so, and thenscraped off.

Any kind of metal or earthenware tank is suitable forcontaining this latter solution, but the caustic sodasolution previously mentioned and the one containingnitric acid must be stored in a glass vessel. For thispurpose, old glass accumulator cases are admirable.

It is not usually necessary for the enamelled parts tobe immersed in the liquid. It is sufficient to brush theliquid over the parts, but in all cases, the parts willneed a final scraping or rubbing down to remove thesoftened enamel.

Tooth Cut Out""

Coil

Winding Slot -2

Coil

WireBinding

TeethRemoved

Figs. I and 2.-A " Growler" assembly and diagram indicating modificationto armature stampings.

size of the wire I must use ? The apparatus isto be used on a 230 volt, 5o cycle circuit.

I also wish to use a similar piece of apparatusfor testing small 3 -phase stators (core diameter :21in. ; core length: 21in.) for short-circuits.Can you please advise me on the design of such a" Growler " ? The apparatus will be used on thesame circuit.-W. Taylor (Ripley).WE suggest you wind the coil of your " Growler "

with 1,500 turns of 18 s.w.g. d.c.c. wire.A small testing appliance for the stator windings

could be made from armature stampings built up to2 tin. long. The diameter of the stampings shouldbe such that, when modified as in the sketch (Fig. 2),they will enter the stator bore. Certain teeth should becut out of the stampings as indicated and a radial slotmade to allow of winding. The coil should be woundwith 2,000 turns of the largest size of s.s.c. enamelledwire which can be accommodated.

Increasing Speed of Small MotorIHAVE obtained a z h.p. electric motor which

I wish to use for dental work. It is 230/250 volts,worked off the A.C. mains. Would, it be possibleto make this into a three -speed machine withoutcausing a serious drop in power ?-W. G. Avery(Witham).IF the motor is an induction motor, having a squirrel

cage rotor, it is very doubtful if it could be rewoundas a three -speed machine without involving aconsiderable loss of power. To advise fully on thispoint we should like to know the inside and outsidediameters of the stator laminated core, together withits length and the number and dimensions of the statorslots. Would it be essential for the motor to be selfstarting or could it be -started by hand ?

If the motor is a series or universal motor, having thearmature winding in series with the field winding, thespeed could be reduced by means of a series resistance.The safe full load torque would be approximatelyconstant, so the safe full load horse power would bepractically proportional to the speed. It may alsobe possible to increase the speed somewhat by meansof a diverter resistance connected across the field coils,in this case the full load torque would fall with increasedspeed, the horse power being practically unchanged

Staining IvoryWOULD you kindly let me know what technique

to adopt to stain ivory in such a manner asto allow the " grain " to show-the colour requiredis any shade of red ?-P. H. Kirk (Kettering).VERY gently simmer the ivory in water for one to

two hours so as to soften the outer skin of thematerial and to allow better penetration of the dye.Then plunge the article into a hot and rather concentratedsolution of the dye containing a little Glauber's saltand some soap, both of which latter materials serve topromote evenness of dyeing. A suitable dyebath wouldbe :

Dye powder .. 8 -to grams.Glauber's salt (Sodium sulphate) .. 3 grams.Soap .. I gramWater .. .. TOO C.CS.The dye liquor should be hot (nearly boiling), and

the ivory article should be immersed in it for about3o to 45 minutes, a little water being added to thebath from time to time in order to make up for evapor-ation losses.

Rinse the ivory in warm water, then dry it in hotsawdust, and give it a finishing treatment by rubbingit over with a cloth charged with a little raw linseed oil.

If darker shades are required, increase the quantityof dye in the bath.

Any water-soluble aniline dye will serve for thispurpose.

Spirit stains (which dissolve in methylated spirit)may also be used, the stain solution being brushed onwith a camel hair brush. In this instance, although thedyeing is easier, patchy results are likely to accrue,'ogether with poor penetration of the dye. Further-more, such colours tend to fade in strong light, andthey can often be washed off with soap and water.

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September, 1946 THE CYCLIST 89

lVa.,

Editor : F. J. CAMM

SEPTEMBER, 1946 No. 295

Comments of the Month.- -

All letters should be addressed tothe Editor, " THE CYCLIST,"george Newness Ltd., Tower House,Southampton Street,Strand,London,

W .C.2.

Phone : Temple Bar 4363Telegrams : Newnes, Rand, London

The Revised Highway CodeTHE Minister of Transport has submitted

to Parliament for approval a revisededition of the Highway Code, and this

must be approved by both Houses of Parlia-ment before it becomes effective. As, however,the present Government has announced thatany opposition from the House of Lordswill be countered by the creation of Labourpeers to outvote them, presumably therevised Highway Code merely needs theapproval of the House of Commons. Suchis the position created by the new democracy.

The Highway Code is a code of direction,lacking the power of an Act of Parliament,and prepared by the Minister of Transportin accordance with Section 45 of the RoadTraffic Act, 193o. It really is a Code ofConduct for the guidance of all road users,and a contravention of the provisions of theCode is not in itself an offence, but may betaken into account in proceedings in theCourts.

Cyclists and MotoristsTHE Code is largely directed to cyclists

and motorists, and only in a minorcapacity to pedestrians. The only offencewhich a pedestrian can commit on the highwayis that of obstruction, and although, as everycyclist and motorist knows, pedestrians aregrave offenders in this and other respects,less than a dozen cases a year are broughtagainst this largest section of road users.As Governments during past years havemade up their minds that our traffic problemscan be solved by regulations and prosecutions,this is somewhat surprising.

We are told that the new Code has beenprepared in the light of experience and onthe advice of experts, and the Ministeracknowledges the valuable work done by allconcerned in the drafting of the documents.

The existing provisions with regard toindividual precepts have been reproducedalmost without exception in the new editiop.In addition, certain new precepts have beenadded, of which the following are the mostimportant :

Paragraph 7.-Watch the children.Accidents to small children are terribly

frequent.Paragraph 8.-If you are a parent or

guardian teach your own children to crossthe road safely and set them an example byyour own road conduct. Do not let yourchildren play in the street. Children underseven should be accompanied by an olderperson when using busy roads.

Paragraph 12.-Wait until a bus or tramhas stopped at a recognised stopping placebefore you get on or off.The section entitled " Hints to Cyclists "

is useful, and is intended to aid the pedalcyclist in the safe use of his machine.

Braking ChartABRAKING chart printed on the

inside of the back cover brings hometo motor drivers the fact that a motor vehicle

cannot be brought to a stop in the shortdistance which many experienced driversthink possible, although what this phraseis intended to convey is not clear. Certainly,it will make experienced motorists smile,and even inexperienced motorists knowthat the stopping distance depends upon theefficiency of the brakes, the speed of thevehicle, the condition of the tyres and thecondition of the road surface. Every house-holder in the country is to receive a copy ofthe revised Code and it will be deliveredfree of charge by the Post Office.

Driving TestsACOPY will also be issued to all new

applicants for driving licences. Whendriving tests, which have been generallydiscontinued during the war, are reinstitutedduring the next few months, candidates willhave to submit to a searching examinationof their knowledge of the Code.

The ultimate object is to make the Codea treaty of good manners between all roadusers. The original Highway Code was firstpublished in April, 1931, and it was revisedin May, 1935. A further revision contem-plated in 1939 was abandoned on the outbreakof war.

A great deal will have to be done by theauthorities before the Code itself can beimplemented by road users. Many of theaccidents are caused by the so-called safetymeasures introduced to prevent accidents.

ObstructionOBSTRUCTION, due to the excessive

use of traffic lights and the all toonumerous road islands and pedestrian cross-ings, is a prolific cause of accidents. Nowthat the various experiments have been triedand have failed they should be abolishedand the roads kept clear for vehicular traffic.

We do not subscribe to the view of theMinistry of Transport and the police thatour roads should be handed over to publicservice vehicles. Many people have to usetheir vehicles in connection with their work,and it is the duty of the authorities to provideadequate parking places for them-cyclesand motor vehicles.

Bus Stopping PlacesTHE fixing of bus stopping places, fixed

some years ago by a committee appointedby the Ministry of Transport is in need ofserious overhaul and readjustment. We alsothink that the principle of paying policemen3s. an hour overtime when they appear inCourt is a direct invitation to the bringingof frivolous charges against road users.

Visit of Australian CyclistsTHE National Secretary of the New South

Wales Pedal Cyclists' Association andAustralian Cycling Association wrote a letteron April 25th to the editor of an Englishperiodical who had criticised the proposed

By F. J. C.

visit to this country of two Australian riderswho were to compete in B.L.R.C. events.

Here is the reply :" I have your letter of 25th April, 1946,

and have observed your comments on theitem regarding a proposed visit to Britainthis season by Australian cyclists to competein events organised by the British Leagueof Racing Cyclists, a comparatively smallBritish breakaway body. The informationregarding the difficulties of a visit fromAusnidia to Britain for cycling purposes wasobtained from a reliable source. You do notprovide any evidence whatever that anyof the statements in the item are in error,and before making any further referenceI would, of course, require more detailsfrom your organisation. Could you answerthe f011owing questions, as this might help ?

" 1$ the A.C.A. sending riders to Britainfor O.L.R.C. events this season ? If so,have passages been booked and all thenecessary permits secured ?

" What British events will your riders beentering ?

" How long will they stay in Britain ?" Are they aware that the B.L.R.C. is not

affiliated to the U.C.A., and that its effortsare regarded with disfavour by the majorityof organised British cyclists`?

" Does the A.C.A. allow its amateur ridersto accept money prizes ?

" How many members has the A.C.A. ?" On the answer to these questions depends

whether I agree or otherwise with your viewthat 1` the whole paragraph is a grossmisstatement of facts.' "

The answer, of course, is that the twoAustralian riders have arrived, and havecompeted. Mr. P. Small, the NationalSecretary, in a message of greeting to theB.R.L.C., said :

" The Australian Cycling Association isvery proud to know that it has fulfilledits promise to the British League of RacingCyclists.

"Alfred R. Strom delivers this message L.)you personally.

" You invited two Australian riders, and-despite most trying conditions-we havesent two. May all the luck of the gods gowith them. We feel that they will be in goodhands."

Now that the Brighton -Glasgow race isover, our contemporary will have had hisvarious questions answered by the eventitself. The letter which he wrote to theNew South Wales Pedal Cyclists' Associationevidently discloses a doubt as to whethertwo Australian cyclists were to be sent tothis country to compete in the events. Wetherefore gladly give publicity to the abovecorrespondence, since it is unlikely it will bepublished in any .other journal, and it is onlyfair that the facts should be known.

We leave our readers to judge the chargeof "',gross misstatement of facts." Thisjournal fairly represents all sides of a question.

90 THE CYCLIST September, 1946

"Raise the StandardMOST cyclists who Nave reached middle

age must have noticed the gradualdecline in the standard of cyclists

on the road ; over the past few years theconduct of a section of clubmen in tea-rooms and inns is nothing short ofmonstrous.

Many of these people belong to what wereonce famous clubs, but, unfortunately, a lotof these have, degenerated into nothing moreor less than sections of the largest of allclubs, "The Kerbstone Wheelers."

Surely we have enough " cyclists " ridingand wobbling all over the road completewith feeding -bottles, ice-cream jackets, etc.,without adding to the number. At onetime members of old -established clubsprided themselves on their conduct and didall they could to uphold the name of thegreatest of all sports ; those who did notbehave in a civilised manner were removed,as indeed they should be.

If we want to keep our place on the roadwe must conduct ourselves as civilised andresponsible members of the community.We don't need to look upon every motoristas a deadly enemy to be inconvenienced ifat all possible ; such a policy is foolish forseveral reasons. Even if we do succeed inholding up a motorist for a few minutes,what do you think his feelings will be whenhe meets the next cyclist, who may be agood roadman, and yet get cut closelybecause of the stupid conduct of some foolwho should not he on the road at all. Thereare some dyed-in-the-wool people in ourranks who say cyclists are always right andmotorists wrong ; that's rather foolish, to putit mildly. There are good and bad in allwalks of life ; generally speaking they aremostly good.

If, for instance, you see an opportunityof giving a motorist a signal which will helphim, you will invariably find that he willgive you a wave of the hand, and as hegoes on his way he will be thinking thatsome of us are at least civilised. We wantmore of the spirit of give and take in ourdaily lives, and, above all, on the road.

Roadside MannersTwenty or more years ago no cyclist in

trouble by the roadside had long to waitbefore a fellow wheelman came to hisassistance ; nowadays, if they notice him atall, it's only to shout some ribald remarkat him and pass on their way. I supposeit's the spirit of the age in which we livethat causes such conduct as this. Surelylife is more pleasant if we try to help oneanother. After all, courtesy costs nothing.

I know quite a few cyclists who are middleaged and have dropped out of club life.These chaps are not snobs, but they justcan't stand the element typical of club lifeto -day

' the clubmen who infest the depots

and shops of lightweight makers are boringand overbearing in their manner, and strutabout like peacocks on the strength of aweekly "25." Longer distances to them are" hard work." After they have done a few" 25s " and failed in a " 5o " or so theypack up the game, having got all they couldout of it and, of course, putting nothingback. The percentage of chaps who tryto help youngsters to become real roadmenafter they themselves have finished islamentably small.

My own entry into serious cycling wascaused by puncturing on. the Hogsback atnight. I was making a very ineffective repairwhen along came a couple of clubmen whosoon did the job, and we rode on together,doing bit and bit till we reached London.

By R. L. JEFFERSON

From then on I began to realise that therewas more in this game than just pushingthe pedals round. There is a history ofnearly 15o years to this game of cycling ;let's all try to live up to the ideals thatwere established by older and wiser genera-tions of wheelmen, and also try to be alittle more humble. There is no need tofeel smart because you've done 13 secondsfor a 220 at " The Hill " ; Jimmy did betterthan that in 1893 on a 64 gear. Thinkthat over. Johnson did under 12 secondsfor a 220 at Antwerp in 1920 ; his wheel-base was 42in., and he sat 6in. behind thebracket, his head angle being 68 deg. Itseems rather remarkable to me that thosewho talk of modern super cycles being fasterand quicker steering still don't go as fastas Bailey, Johnson, Ryan, etc., of 20 or moreyears ago on the same track. The fact isthat the older generation had the ability totrain and live right. They lived, breathedand oozed cycling, and that's what anyracing man has got to do if he wants toget his wheel in front of any foreigner atthe world's championship.

Attracting the PublicLet us realise that we have a long way

to go to raise the standard of cycling soas to attract the public. At present theman in the street regards cyclists as a noisy,vulgar mob. Can we deny that some ofus are guilty ? Don't forget that thehooligans on wheels are always noticed; thequiet chap isn't. If you have a few hooli-gans in your club, try to educate them ;point out what fools and traitors they are.

If they don't see reason, get rid of them ;they will only serve to bring discredit onyour club. Don't try to be the lord of allcreation when you're out on your iron ;remember if it hadn't been for men likeMacmillan you would probably not becycling at all.

Ours is the greatest of all games. Wehave the modern magic carpet to travelon, to enlarge our horizons, to give usmemories that one can't read in a book orbuy id a shop. Let us not abuse ourprivileges, but show by our conduct thatours is the greatest of all games. We willget recruits to our ranks who will get others.that is our plain duty as decent cyclists.

A National Sport !I for one want to live long enough to

see cycling become a national sport in thesense that football and cricket are. Thiscan come about if we wish it, but we'vegot to improve a lot. We've got to be lessselfish, less noisy, and those who race havegot to take it far more seriously. Alsowe have to eradicate the paid amateur andgive an equal chance to the youngster whocan't afford decent equipment. If a manis known.to be in receipt of equipment ormoney from a maker, ipso facto make hima pro or bar him from competing withamateurs. It's all very well paying lipservice to pure amateurism and wilfullyclosing our eyes to things which We all knoware going on.

So for the sake of the game let's make1946 the first year of a great revival ofcycling, and a reawakening of interest bythe man in the street. By our conductshall be judged. It's up 'to us all to proveour worth and earn our good name.

ParagramsBicycle for Two-SometimesAN Italian cyclist has evolved a special kind of

£ tandem, the rear portion of which can be quicklyunfastened so that the tandem forms two separatecycles. The unfortunate part of it is that after theseparation there are only two wheels for two cycles,so it is not wise for the riders of the tandem to disagreewhile out on a run or one of them will have to walkback home.

Kettering CelebrationMR. TREVOR KILMISTER, of Birch Road,

Kettering, captain of Kettering Friendly CyclingClub, celebrated his coming of age by inviting themembers of the Club, With other friends and relatives,to a tea and entertainment at Kettering Central Hall.Mr. Kilmister was presented by the Club memberswith a leather writing case.

Proposed Damming of LoweswaterA STORM of controversy is likely to be caused by

the recent proposal that Loweswater shall bedammed, and the waters of Mosedale Beck impounded.

What effect the damming of Loweswater wouldhave on its scenic value is hard to gauge. The lake isdependent for its attractiveness on the views overCrummock and Buttermere, its sister lakes, and of themountains grouped around the three waters.

The engineers describe as " most attractive " ascheme for impounding the waters of the MosedaleBeck, " particularly if other authorities joined in andreaped the benefits themselves." Mosedale is thenarrow valley between the fell of Melbreak dominatingthe east side of Crummock and Hencomb. Here awayfarer on his way from Loweswater to Ennerdalemay see, as probably nowhere else in the Lake District,the rarest birds of the mountain ranges, the peregrineand the merlin, not to mention the raven and thebuzzard.

Conferences of the local authorities have alreadytaken place, and they are agreed that the implementationof the County Council's report on the subject mustremain a matter foi the local authorities concerned.

Clock From Cycle PartsMESSRS. H. U1'PADINE AND SON, cycle

manufacturers, "Why, near Doncaster, haveconstructed what is probably a unique clock. The

whole of the clock is constructed of cycle parts and isdriven by a weight. The face is a specially made6o -toothed chain wheel, the hands are cycle cranks,and the movement is built up from gearwheels and chain.

Seventy Years a CyclistM.R. W. H. WOOD, of Gainsborough, Lines, rho

has been a cyclist for 7o years, and a choristerat his church for 6o years, celebrated his goldenwedding recently by cycling to church to sing inthe choir.

The Fines Fly TooTHE difficulty experienced in obtaining payment of

fines imposed on airmen, most of whom arecaught cycling without lights, was referred to by theclerk to Kettering magistrates when two airmen askedfor time to pay. He said : " Many airmen have beenfined at this court and then they move to anotherstation. Pursuing them, we discover they have againmoved and finally, before we catch up with them andthe fines can be paid, they have gone overseas."

One of the Centresgal LE old milestone in Long Street, Atherstone,

Warwickshire, one of the several places claimedto be the centre of England, has been cleaned afterbeing smeared with tar during the days of possibleinvasion. In addition to the well-known inscriptionshowing too miles to London, too miles to Lincolnand too mites to Liverpool, the cleaning has revealedfurther lettering, which reads : " Litchfield as,Lutterwoith 171 and London too."

ToughCHARLIE WILLOUGHBY, 70 -year -old Lincoln-

shire farm -worker, who still cycles a dozen milesor more when he wants a drink of beer, wears a pairof velvet fustian trousers which first came out of thetailor's shop 107 years ago. The trousers are old-fashioned in cut but show few signs of wear, in spiteof Charlie having worn them for 4t years after theoriginal owner ceased to have any need of trousers,

International T.T. in the Isle of ManRFFERRING to the illustration on page 82 of theA% August issue, the caption stated in error thatthe riders were taking the hairpin bend at GovernorsBridge, Douglas. It is, of course, the famous HairpinBend at Ramsey.


Around the Wheelworld

The B.L.R.C. Brighton -Glasgow RaceAS one would naturally expect with an

organisation like the B.L.R.C., theBrighton -Glasgow race was a well -organisedaffair, and was carried through withouthitch, without accident, without incident,without police opposition, but with police

. co-operation and collaboration, and as usualwith B.L.R.C. events it was well supportedby the national press, and by editors whoseminds are not still buried in the past or whoare advised by those with minds similarlyinterred.

I understand from one of the officialmouthpieces of the Minister of Transportthat he does not like this form of racing, andtherefore would like it abolished. As theB.L.R.C. massed start races are run in strictaccord with the law (indeed, the B.L.R.C.would welcome police action. against anyof its members who broke the law ; theywould themselves take action against therider), the League is not concerned with thelikes or dislikes of Ministers. Only an Act ofParliament can set this form of racing aside,but with it would go time trials and roadrecords. The fact that the N.C.U. and theR.T.T.C. and the R.R.A. and the C.T.C. donot like this form of racing either is not anindication of national cycling opinion, as isevidenced from the vast numbers who takean interest in it, and turn up to witness thevarious stages of it.

Sir Stafford Cripps, I am given to under-stand, does not like meat, alcohol or tobacco,and if every citizen were to kow-tow to thelikes and dislikes of various Cabinet Ministerslife would indeed be intolerable. I, for one,am going to enjoy my cigarette and my rumpsteak (when I can get it) and my modicum ofalcohol (also when I can get it), and I presumethat cyclists of a similar mind are going tohave their massed start racing.

Because one or two of the faint -heartshave rejoined the N.C.U., some of the morepontifical of the cycling scribes seem tothink that 1946 will hear the Swan Song of theLeague. I can assure them that they willhear their own Swan Song first.

Terrific congestion is caused by the LordMayor's Show and the Boat Race, for example,but no one suggests that they should beabolished. The League events can be of equalnational importance, and I am glad to thinkthat the B.L.R.C. refuses to be brow -beatenby the so-called national bodies.

B.L.R.C. versus N.C.U.

IN a journal appropriately entitled,I Challenge the B.L.R.C. and theN.C.U. present their cases in parallel form.No disinterested party free from bias orblinded by hero-worship can fail to recognisethat the N.C.U. lost its case. The B.L.R.C.case is well known, and so I merely quotefrom the N.C.U. case as stated by the nationalsecretary of the body.

" The public authorities . . . lost no time inmaking up their minds that the King's high-way could not be used as a race track. . . .

They were supported in this by a very largemeasure of public opinion." I should liketo have evidence of this public opinion.Did not the national secretary here meanpolice opinion ? As the N.C.U. at that timecontrolled all cycle sport it was the duty of thatbody to represent cycling opinion, not ill-informed public or police opinion anyway.The fact is that cyclists at the time were soannoyed with the N.C.U. that they brokesway and formed rival bodies.

By ICARUS

" A way was found (the time trial system)where speed tests can be indulged in withoutinconvenience to traffic or congestion of thehighway generally."

The inference here is that massed startevents as run by the B.L.R.C. are causingcongestion and inconvenience to other traffic,when as the national secretary knows fullwell this is not the case, although it mayhave been in the days when the effete N.C.U.ran massed start racing.

The modern races are efficiently run, thecourses are well marshalled, the policeco-operate, and all of the evidence shows thatthere is an entire absence laf congestioneither at the start, during the course of therace, or at the finish.

The national secretary has to admit in thecourse of the article that " there was un-doubtedly a strong feeling that time trialsshould be abolished, but the responsibleMinistry, having examined the rules of timetrials and seen the position, stated that so longas they were continued on those lines they sawno reason to interfere."

Why, therefore, did the N.C.U. ban time -trials and forbid its officials from taking partin them ? As the N.C.U. was wrong abouttime trials there is good reason to suppose thatits judgment is equally unsound on massedstart, a point which " the responsibleMinistry " would do well to remember. Inother words, the Ministry can safely ignorethe opinions of the N.C.U., for fifty years ofroad sport have proved how wrong they werein throwing it overboard and causing thecreation of other bodies such as the B.L.R.C.,the R.T.T.C., and the R.R.A.

The C.T.C. I dismiss as a body of littleimportance as far as sport is concerned. Itknows little, if anything, about it, and ismainly concerned with cycle touring; althoughthe Minister might bear in mind that someof its district associations have hard riders'sections whose events amount to massed startraces. I believe that the C.T.C. can alsoerect " Dangerous Hill " signs, on hillswhich are by no means dangerous to -day.

The Minister is also informed that viewsof members of the C.T.C. on the subject ofmassed start racing are not necessarily theviews of the C.T.C., which has not expressedan official point of view about it; nor is itcompetent or authorised to do so.

Cycle Tube Repairing by VulcanisationAN interesting outfit recently introduced

by Mr. William Frost, the well-known pioneer of repairing vulcanisers inthis country, is the " Autotherm " CycleTube Repairing Vulcaniser, whith per-manently seals and reinforces the damagedarea of the tube, synthetic or natural rubber,by a reconstructive method which, in effect,duplicates the original manufacturing processat the point of repair.

The Autotherm Vulcaniser itself is a smallbut efficient vulcanising press, a substitutein miniature for the vulcanising presses usedin rubber factories everywhere. It is handyand extremely simple to use, by the roadsideor elsewhere, yet fulfils all the requirementsof scientific repairing by vulcanisation.The outfit, which is sold at the extremelymodest price of 7s. 6d., is complete in everyparticular, and includes an initial supplyof repair -heat units (2 in 1) as well as othermaterials for a variety of jobs, such as hot-water bottles, football bladders, and othersmall rubber articles.

To many cyclists, the idea of repairing theirtyres by vulcanising may be a novelty.

It should be pointed out, however, that thecompulsory use of synthetic rubber hasreduced the reliability of patching andemphasised the value of vulcanising forpermanent work. The Autotherm method isjust as easy as patching, it is interesting andeven fascinating to young cyclists, and can becarried out by anyone with complete success.

The Autotherm Vulcaniser has alreadybeen on the market long enough to prove itselfas an indispensable outfit for cyclists, and auseful shop appliance for cycle traders.

The " Autotherm" cycle tube repairingvulcaniser in use.

If there is any difficulty in obtaining theAutotherm outfit, cyclists should send thename of their usual cycle dealer to WilliamFrost Products, Ltd., Kautex Buildings,Elstree Way, Elstree, Herts.

The Trader HandbookTN spite of paper restrictions, new features1 have been added to " The TraderHandbook " (motor, motor -cycle and cycletrades), the fortieth edition of which has justbeen issued by The Trader Publishing Co.,Ltd., Dorset House, Stamford Street, London,S.E.r, at 7s. 6d., post free. The chief additionis a complete list of index marks or regis-tration numbers allotted to motor vehicles bythe Licensing Authorities in the UnitedKingdom from 1904 to February, 1946 ; withthis list it is possible, with few exceptions, toascertain the approximate age of any motorvehicle. Another new feature is a...table ofspecification details of cars, commercialvehicles and motor -cycles put on the marketin 1946. ;There is also a completely revisedlegal guide for traders, a " Buyer's Guide,"and an alphabetical list of some thousands ofbranded goods used by the motor and cycletrader, and a directory of manufacturers,factors and wholesale suppliers to theseindustries. Much other useful technical andgeneral trade information is included in the312 pages of this handbook.

New Works DirectorFOLLOWING the retirement of Mr. J. H.

Furniss after many years service withthe company, Mr. Walter F. Withers,A.M.I.A.E., has joined the Hercules Cycleand Motor Co., Ltd., as works director, ingeneral control of the Rocky Lane and ManorMills factories.

Mr. T. A. Yapp, M.B.E., will continue asworks manager of Manor Mills Factoryspecifically, and Mr. P. J. Lester as worksmanager of Rocky Lane Factory.

Mr. Withers, who has had exceptionallywide engineering experience in Birmingham,was formerly works director of Wilmot -Breeden, Ltd., and his appointment to theHercules Company is in line with theirextensive post-war plans in relation to thedevelopment of cycles and three -speed hubs.


Better InformationT AM convinced that what this pastime of ours1 needs is a better -informed public. I supposethe majority of people would say they know all aboutcycling having once ridden a bicycle, but in my opinionthe first part of that sentence would be gross exag-geration, to say the least of it, for the majority of peopleare ignorant of cycling in its proper sense, and knowfar too little about the bicycle or the way to ride it,if their purpose is to wander freely and easily over thislovely land. It is astounding that such should be thecase considering the bicycle has passed its century, and,really, I blame the makers and sellers of their machinesfor such a state of affairs. Observation alone wouldreveal this ignorance to any expert rider, but I am notrelying on that only. Occasionally I consort with acrowd of people, young and not so young, who haveformed social clubs for the purpose of decoratingleisure, and they ask me to tell them about cycling, whatI see in it, what I get from it, why I keep riding whenI need not, and why I ride the type of machine theycan examine. Such folk are a fair sample of thatcommunity seeking a way of life to give them joy intheir leisure time ; and I say from intimate knowledgethat their ignorance of the pastime is colossal. And thefact that many of them use bicycles or have done soin their time merely exaggerates the state of suchignorance. I do not expect everyone to know cyclingas intimately as I imagine I do, but I would expect

'such folk to understand how to buy best and how to usetheir purchase for that widening of physical and mentalhorizons that is at once a joy and adventure, an exercisein health and a pleasant attraction to anyone fond ofthe country and concerned to add variety to life.

A Wider PublicityIT is difficult to put the story of cycling over to

such people in a brief talk, difficult to break downthe long standing prejudice that cycling is " hardwork," and really a trifle infra dig. to folk with a gentlesense of their own importance. And curiously enough,most of them seem really interested in your story, andoften a trifle covetous of the healthiness you display,and the enthusiasm that emanates from the impromptusentences. The soil is right to receive the seeds ofcycling propaganda, but the seeds are missing, or atleast are only scattered in such haphazard ways asthese indicated. Cycling was once the interest of thedaily press, but where is it now ? Yet there are moreriders than ever, and all of them are readers to -day,and there would be far more potential cyclists if thegood gospel of the pastime could but find a proper placein the pages devoted to the sports and pastimes. Maybewhen paper restrictions are removed we. shall see achange and cycling will find a place in the columns,for it deserves one, not merely for the numbers inter-ested, but because it is perhaps the worthiest of allgames to fill with joy the leisure hours of a greatcommunity. Indeed, if this lovely land of ours is tobecome a playground for holiday folk, an attraction toforeign guests, and a means of making Britain morethan a name on a map-as our authorities appear todesire-cycling must play a major part in such a desirabledevelopment, for the simple reason that it is the

'cheapest, as well as the healthiest means of movement.;Therefore, I say that we need to teach people how toride and what to ride and why, for the joy of the gameis bound up with the correct method of playing it, asis the fact with all games, and that especial developmenthas been neglected for years. It is time we all awakened,for the conditions were never more favourable, and theindustry never stronger to urge their interests in themanner of publicity for the benefit of the pastime. Thetechnical press, the daily. press and the B.B.C., suchare the avenues, and if the industry is wise it willsupplement these with its own Book of the Bicycle,as a free gift, telling people the best way of using itsproducts for the pursuit of freedom, health and happi-

ness, by presenting everypurchaser with a copy.Think what an attractionsuch a volume could be, anindex to another life inparagraph and picture, ameans whereby folk couldbegin to understand whatcycling can mean to happi-ness-for no man can tellthe whole story because itsindividual joy is beyondexpression.

One Day OutT CARRIED out my own1 precepts one goldenSunday some weeks ago,and it was indeed aglorious day. There were acouple of us, both well oversixty, and because we hadnot seen the Avon andSevern Valley from the ridgeof Fish Hill above Broadwaythis year, we decided onthat route by way of Bidfordand the Roman Road tothe foot of Saintbury Hill.We were in Bidford juston eleven o'clock for theusual cup of tea, and bythat time the sun was reallypowerful anti every traceof the overnight frost haddisappeared. I looked outfor violets, but apparentlyit was still a little tooearly for the hedgerow kind,

though some of the cottage gardens showed peeps,with the white bell of the snowdrops in profusion. Wetook an easy turn along the Roman Road, for thegrade runs slightly up and the wind came steadily intoour laps, but just before one o'clock we were at theTower on the edge of Fish Hill and looted at thedazzling picture of the vale, half Idddeif and halfrevealed in the haze of an azure day. Finding nosolace of refreshment on the ridge we dropped intoBroadway for a lunch of sorts and the cheery flicker ofa fire, and soon after made quietly for honie by way ofWelford, Binton and Aston Cantlow. It was justglorious, the day and the easy loping speed-the windwas now abaft-and the happy talk of how often wewould do this thing and fill some of our Sundays withcontent. We had tea in Henley -in -Arden, a mighty teaof toast and an egg and buttered scones, and in thegloaming drifted home the dozen miles to makeup a run of well over seventy. In the quiet momentsbefore bedtime I thought-as so often is the case inthese latter days-how lucky I am to be able to dothese things, to use so lovely a day for the joy of visionand burn the miles away with an easy energy thatleaves me nothing more than happily tired at theend of them. That is whatcycling can do for you rightdown the years if you will letit, and it is an abiding mysteryto me that so comparatively fewfolk have discovered the fact.

And Stormy TimespRIOR to that ride I had an-1 assignation on Saturdayafternoon when a full-bloodedsouth -wester drove a biggervolume of water at me since theyear started. Fourteen mileswould see me there, and anhour and a quarter of time.But I had not reckoned with thegale. It was low gear for choiceon any rise, and a horizontalposition to escape the wind andkeep the rain from half blindingme. In an hour and a half Iwas there, ruffled, a trifle damp but very,ilap.py, and I think the

latter condition was mainly dueto that feeling of egotism weall experience on the com-pletion of such a journey.You have done something andyou are glad you were able.A roaring stove and a satisfyingtea was the prelude to acouple of cheery hours withthe lads and lassies, so that thestruggle, was worth the effortindividually and collectively.With another early bird I leftthat comfortable hostel just oneight o'clock with the gale atits height driving the rain onhurrying, ghostly legs alongthe road, but now we wereall travelling in the samedirection. That was a greatride, following the flicker ofthe lamp's beams with thewater running down thebacks of our ears. Wemade home in an houreasily with no more dampness than the fringes of ourhair. Yet weather of this kind seems to appall somepeople who positively shudder at riding in suchconditions. Believe me, it is never .so bad as it looks,and the only risk of real discomfort is the very remote

one of sustaining a puncture or some mechanicaltrouble. If cycling was all fine weather, blue skies andfair winds it would lose much of its adventure, and formyself, I do not intend that it should.

No Immediate HopeArt! me, I was told the other day by a big makes

that any hope of switching over to new types ofbicycle with better material and equipment was verydoubtful as far as this season is concerned. The world'shunger for bicycles is so great that manufacturers cannotmeet the demands, and all the available labour isconcentrated on output, leaving little or nothing overto give attention to the first-class stuff or put into pro-duction all those improvements so glibly promisedduring the war. This man said quite frankly that theposition is disappointing ; he wanted to improve thebreed, to get down to the type of machine which heknew was in demand in the home market ; but thefact was that export must come before the highestquality, and export is the business on which he wasconcentrating. But I have reason to believe that weshall have good rubber tyres to buy in the not too -distantfuture, and this is a relief, for it will aid us to keep theold machine running with something left of its oldliveliness. If we cannot feel any joy in the position itis at least something to know we are far better offthan cyclists in any other country, not excludingU.S.A., where they have yet to learn what real cyclingis. So it is a matter of saving your money for themoment, and " make do and mend " with the oldmodel ; the new one, when it is available will seem allthe sweeter.

PrayerTHIS paragraph may not catch the eyes of my

motoring friends, but if perchance it does dropinto the consciousness of a few of them, I would askthem to listen to my prayer. On stormy days, whenthe wind howls down the street and the rain hits meobliquely in the diaphragm, some motorists pass meuncomfortably closely 'when there is no need lotshaving tactics. They seem to forget my single trackvehicle cannot be held on a dead true course when thegale comes howling round the corner at fifty an hourand a ballooning cape has to take the impact. It ismerely asking another road user to show a sense ofdecency and good manners to the vulnerable traveller.The other desire I would like to see self-imposed bythe motorist is a greater consideration for the discomfortimposed on pedestrians and cyclists when he fails toslacken speed passing or overtaking on a rain -floodedroad. It is most unpleasant to be presented with afootful of dirty water, and I don't know what someof the ladies think when their garments are bespatteredby the thoughtless action of an urgent driver. It is onlyduring excessive storm times that I would like tosee motoring consideration given to these matters, brit,unfortunately, the majority of drivers are eitherignorant of the discomfort and damage they fling atother people, or they just don't care. I prefer to believethe former, for human nature is mainly selfish becauseit is mainly thoughtless, and a word in season may leadto an attempt at improving the present attitude towardsthis question. If cyclists splashed cars-never mindthe passengers-in the same way cars splash cyclists,there would be a bother, and it would be justified.

historicCouncil Pouse

ShrewsburyZaaes. IC was lie last of

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"No other tyrewill really satisfy me now"

BEST TODAY * STILL BETTER TOMORROW


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The firmill/he roadThe turn in the road,ever revealing theunexpected, is one can cycle in safety if you fitof the fascinations ofcycling. But it mayalso reveal an un-expected emergency:be ready to meet it. ALL-WEATHER BRAKE BLOCKS

Remember, rain or shine you

FERODOFERODO LIMITED

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CHAPEL -EN -LE -FRITH IFERODOI,IF613 TRACI, MARK


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The Vexed Question of Bell -ringing

IDO not refer to the tuneful ringing ofchurch bells, but to the " warning

bells " of cyclists. Some riders have apassion for ringing their bells, and to mymind there is little or no use in the prac-tice. I wonder how many riders havemachines without bells ? The number mustbe great, and I am not sure that it is notbetter to be minus a bell than to be addictedto the habit of constantly " tinkling."Personally, I have a bell on my machinebut I very rarely use it, and do not findthat it is often necessary to do so.

Gay Father ThamesTHE other Saturday I spent some time

at Marlow and recaptured somethingof the romance and charm of the Thames.It was a hot and sunny day ; punts andboats and yachts were out tit plenty, andswimmers dived from the brie* with skilland grace. And on the spacious lawns ofthe " Compleat Angler " folks sat and dozed,or drank tea, or gazed upon the water. Allvery peaceful and all very English, and Ithoroughly enjoyed my visit. And ridingin the Buckinghamshire country is alwaysgood . . . it is a county I love, particularlyin the autumn, when the beeches are attheir very loveliest, and one may ridethrough leafy lanes, communing with thespirits of Milton and Penn and gentleCowper . . . all having strong links withBuckinghamshire.

Lure of the Night -rideWHEN darkness falls, and the owls hoot

in the spinney, and the moon castsa silvery radiance over the familiar country-side . . then it is that I like to take outmy bike and go for a spin. Night-timetransforms the world, softening the lines andcorners and imbuing objects with newbeauty. And the long road is deserted .

a ribbon beckoning on to romance andadventure. The little village which was sofull of bustle and activity when we rodethrough it on that summer afternoon is nowwrapped in sleep ; the inn is shut ; the greyold church looks almost eerie in the moon-light, and we are in a quiet and strangelybeautiful world. I often wonder why more

4/ Ie.,.

cyclists do not indulge in night -riding, forit is fascinating and most soothing to thenerves. Try a moonlight spin when youhave had a particularly worrying day ; itwill do you more good than a bottle ofmedicine, and you will be surprised howdifferent your familiar road can look whenkissed by the moonbeams!

"See Britain by Cycle"

THE title is not mine . . . but that of anew and interesting series of advertise-

ments issued by Dunlop and appearing inthe cycling press. The series depicts variousfascinating places it is possible to visit bycycle, and is finely illustrated by that goodartist, John Pimlott. Canterbury, CorfeCastle, Ullswater, Snowdonia, Polperro, andFlatford Mill, and all the delightful scenesof the Stout and Constable country, all arefeatured in this series, and I have no doubtthat many cyclists have cut out these adver-tisements and filed them for ready referencewhen touring. It is a truism that advertisingcan be educative and informative, and thisseries is pleasing proof of the fact.

Is it Really Necessary ?T REFER to the-I- habit of calling aplace where teas aresrved " Ye Olde TeaShoppe." I hate thepseudo "old andarty," and it is strangethat genuine old cot-tages should be marredby such cheapinscrip-tions. The countrycottage where a cyclistmay obtain tea andrefreshment fills agreat need, and itssign is ever welcome

. . but I do plead for terPr..the dropping of " Y.eOlde "-t o me italways makes the tealess drinkable, andwhatever food is pro-vided in these daysof austerity, 1 e s spalatable!

" A Cycling Adviser "CLUB secretaries and members of clubs

in Southern England are to have anexpert adviser on tyre and rim equipmentat their service. He is Mr. F. A. Borton,and he has excellent qualifications for hisnew appointment. He has been a keencyclist for more than twenty years, and foreighteen years prior to the war he actedas secretary of Harrow Cycling Club. TheDunlop people have now appointed him toa special position to study and look afterthe needs of riders and give advice on theirmachine equipment and its use. Mr. Bortonwill be in close touch with light -weight cyclebuilders and assemblers. It is the sort ofappointment I welcome, and many riderswill, I know, be pleased at this extensionof Dunlop service to the movement.

The Raleigh Handbook

MY good friend Fred Keller, the busyadvertising manager of the Raleigh

organisation, informs me that the first editionof the Raleigh Cyclists' Handbook, pub-lished early in the year, has been sold outand that a new edition is contemplated. Iam not surprised at the success of the firstedition, for the handbook was a model ofall that such a publication should be:concise, easy to read, and of handy pocketsize. I often wish that more cyclists wouldread some simple instructional manual aboutthe care and upkeep of the cycle, for onestill sees many cases of gross neglect andmaltreatment.

The B.B.C. and the CyclistAN ardent rider was talking to me the

other day and asked me why moretalks were not given by the B.B.C. for thespecial benefit of cyclists. His contentionwas that the Corporation neglected thecyclist and the cycling fraternity. Is thistrue ? I certainly cannot recall many talksdevoted to our " game" .. . and one wonderswhy. What a mine of treasures exist inconnection with the history of the cycle,the stories of famous cycling clubs, the featsof old-time riders, and the delights of cycletouring! The B.B.C. has, I realise, amighty problem to cater for all tastes andall classes . . . but think of the millions ofcyclists in this country! Maybe it is timethat the " talks producers " did somethingabout it.

4st

710

96 THE CYCLIST

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My -Pointof View

and leading a hectic life foran hour in the morning andan hour in the eveningwhen everybody, with oneaccord, is intent on simul-taneously travelling to orfrom his (or her) work. Aremedy suggests itself toone who, as indicated, hasfor so many years suppliedhis own transport. If moreand more people wouldmake a point of cycling toand' from their work howmuch better it would befor everybody concerned!The public transport situationwould be eased, but, betterstill, the boys and girlswould find it a great advantageto be riding to and fro. Itis a healthy business, andconvenient withal. Thi:bicycle provides door-to-doortransport, which , is alwaysready, always available. Nowait ing --- no crowding - no

... Asto queues --no steamed v, indows--no_breathing of the air with

LU111.1CifOIN.C1IlyCk.Sussex .

One of Irsqlands- smallest -churches. A lonely little

surrounded k treesofi the main road from Westbean to Alfriston..Only the chancel nun:sins ofthe onginal huildmq whicit wasdestromed centuries. ago. by

By " WAYFARER "

Good HabitAN advertisement in the Personal column of. The

Times led off with the words : " Riding Habit .j.22." The habit of riding (bicycles) is a very goodone, which I possess. The price, however, is doubtful.

They Don't TryWHEN I stopped for tea the other day, the caterer

asked me how far I had come. The reply," 6r miles," brought the retort : " Coo ! I'd he deadff I rode six miles ! " Not literally, of course-but somany people could do so much more cycling if onlythey would try. You cannot excel at piano -playing,or climbing mountains, or knitting socks, or ridingbicycles, without practice, backed by the will toconquer. There is so much fun, and so great a benefit,to be extracted from our recreation, that I wondermore folks do not make an effort to get " value formoney." The reward is waiting for them-but ithas to be earned.

which, for the moment, otherpeople have finished ! Cyclingto and from work has a greatdeal to commend it. It is

"" worth trying.

Shut up !AMIDLAND daily newspaper recently reprinted

a paragraph from an issue of 5o years agornconceing the stag -beetle's habit of flying about in

the gloaming, and, " the cool of the day being alsothe hour of the bicyclist " (!), a warning was issuedconcerning " the peculiar danger " arising, one of thesebeetles having flown " straight into the mouth of aninnocent cyclist." The majority of cyclists, it wassuggested, ride with their mouths open. Just fancythat ! It must have been a poor issue of the newspaperconcerned if the foregoing were judged the mostsuitable paragraph for quotation half a century later IStill, the right plan for cyclists is to keep theirmouths shut.

Rain InfrequencyOWING to the folding -up of the war job on which

I have been engaged for the last six years I havejust ceased to cycle to and from work. For most ofthe half -century (and more) during which I was in

'business the bicycle was my travel medium, and thepoint is mentioned at this juncture merely so thatcomment may be made on the use of the weather -protection I always carried. No record, of course,was kept, but, despite the notorious recklessness of ourclimate, the number of times I have had to make mydaily journeys wearing a cape seems to be relativelylow. It was felt, at times, that the number was far toohigh, especially when a stop had to be made en routein order to don my regalia (on such occasions I waspretty fluent on the subject !), but I am sure thatstatistics would reveal quite a small percentage ofjourneys under cover. 'Which is remarkable, con-sidering the acknowledged instability of our climate.

RemedyWROM this point it is an easy step to take in order-a; to make reference to a problem which is atpresent troubling the transport authorities of the greatcity which I adorn with my presence. The difficultiesattendant in the morning and evening peak hours arebecoming more and more acute, and the powers -that -beseem to feel that, in the absence of more staggering "on the part of business firms, there is bound to be someform of collapse of the existing arrangements. Thereis the further point that a Considerable proportion ofexpensive trams and buses are used for only a shortperiod daily, spending most of their time in garages,

Code Advice,'"1.{1" UNDERSTAND that the

revised Highway Codecontains the advice thatdogs shOuld be kept undercontrol, whether on the roador in a vehicle. " Manya person," we are told," has been killed or injuredbecause the driver swerved toavoid a dog." Yes; and manya cyclist has sustained a nasty

fall owing to the fact that dogs are allowed to roam thepublic highways just as they fancy. Some day, perhaps,there will be legislation on the point, carrying with itthe implication that, broadly speaking, human life isof greater importance than the canine equivalent.

Radiant MemoryOF all the countless pictures which hang in the

storehouse of my mind one of the most preciousrelates to the first of two days devoted to the traverse,some 23 years ago, of what is known as the Ring ofKerry-or the Grand Atlantic Coast Route. A pairof us, on our initial visit to Ireland, stayed for a coupleof nights in Killarney, an action which prompted anIrish; cycling journalist to voice the silly and somewhatSpiteful remark that we " had done Killarney byCandle -light." Then we set forth to ride fromKillarney to Killarney by way of Kenmare, SneemWaterville, Cahirciveen, Glenbeigh, and Killorglin,with a detour to Valencia Island, and the journey wasa joyous one.

I had previously seen mountains, but never suchmountains : never had I-never have I-been soimpressed and inspired by the earth -lumps whichentered into our vision. A matchless panorama fellto our lot. We saw something of the jungle ofmountains which constitute the real Killarney, thetown of th.at name being little more than a slum,dominated by a fine cathedral. We saw the mountainsacross the broad waters of the Kenmare River, andthose across the broader waters of Dingle Bay. Some-times these great uplands were in full view ; sometimesthey were partly concealed, partly revealed, by cloudswhich hurried over the scene. We saw, too, some ofthe " drowned mountains " lying off the west coast ofIreland-chunks which might easily have risen fromdry land instead of from the bed of the ocean-and thesight was an impressive one.

No doubt we were both under the influence of thespecial glamour attaching to a first visit, causing us toview things through rose -tinted spectacles. No doubt,too, we were influenced by our remote location-bythe fact that we were about as far from home as wecould ever expect to be in these islands. Remotenesshas always appealed to me as a cycle tourist ; I alwayslike to get a hit farther away-and still a bit farther.

Since those far-off days I have seen many uplands,including near and far views of Snowdon, Cader Idris,and Plynlimon. I have looked at Ireland from Scotland,and at Scotland from Ireland. I have viewed theto Bens of Connemara from the south side of GalwayBay, and the mountains of Killarney from the northside of the River Shannon, as well as from the Mallowroad. I have ambled among the Wicklow Mountains ;I have seen the. Mountains of Mourne from the footof Howth Head, 6o miles away. I know the backboneof England by sight, and have gazed at the LangdalePikes. Pictures of the Coolins hang within my mentalstorehouse, and I have dwelt visually on the tumbledwest of Scotland's mainland from vantage points inSkye. From various places my eye has ranged overthe Inner and Outer Hebrides. But, if I have toaward the first prize for beauty, combined with inspira-tion, then I award it in respect of those two Augustdays in 1923 when I made the circuit of the WatervillePeninsula. A radiant memory, indeed !

The Magical BicycleT HAVE often spoken, with conviction, of the bicycle-1- as a magical instrument of travel. Possibly, thatalmost supernatural characteristic of the two -wheeleris to be found, in excelsis, in the case of that small

September, 1946

army of people, mostly women -folk, who have nevermastered the art -of balancing a bicycle, and who yetride thousands of miles every year. The answer tothis superficially insoluble problem is, of course, thatsuch people occupy the back seat of tandems. Theyare all cyclists-but they cams* ride a bicycle ! Theyare enthusiasts on cycling-but they must have com-pany ! Some of the keenest women cyclists I knowere the people who, 'for one reason or another, wouldbe completely -at sea if they were asked to ride a single.Yet they account for thousands of miles every year,thanks to the magical bicycle.

Another aspect of the magic attaching to the bicyclehas just come to my notice. A young relative of minewas recently found to be afflicted with contraction ofthe muscles, following child -birth. Her doctor --obviously a man of sound common sense-said thatthere was only one thing for it : she must resumeher cycling. So the tandem, which had been put awayfor the time being, has been extracted from its lair, andhusband and wife are enjoying themselves awheel in aquiet sort of way, and to the advantage of both parties.

Pernicious DoctrineMY daily newspaper, in reporting on the recent

Royal visit to Cheshire, spoke of "the towns ofNorthwich and Nantwich, where the streets are dan-gerously narrow." This is a pernicious and poisonousdoctrine that a cramped space means danger. It doesnothing of the sort. Of itself; a narrow street orbridge, or a steep hill, can never cause danger. It isthe traffic which persistently ignores the obvious con--

that creates the danger.

Follow the LeaderI PAUSED, foot on ground, at the suburban road

intersection, in order to let the cross traffic flowpast. A stationary motor -car was on my right, andone or two others were panting behind me. When anopportunity came for me to negotiate the intersectionin safety I took it. The motorist immediately behind''me, unsighted by the still stationary car, decided tofollow the leader.. He overlooked that a cyclist cannip over a road very quickly, and he failed to appreciatethe circumstance that. No. 2 in a procession cannot ofnecessity do what No. a has achieved. A squealingof brakes prompted me to glance back when I reachedthe " still waters " of my desire, and I saw that twomotor-cars-the one immediately behind me andanother hurrying up the road at right-angles-hadnearly kissed each other. This little incident has itslesson for cyclists. Don't cross the road if your visionis obstructed ; don't assume that what was safe for theman ahead will be safe for you also.

" Shortening the Tourney."ICYCLED home one Sunday in the early summer

with a man whom I do not often see and, whenthe parting of the ways came, he thanked me for mycompany which (he said) had had the effect of " shorten-ing the journey." He did not quite mean that. As ageneral rule, we cyclists do not seek to abbreviate ourrides, though there are exceptions to the rule. Whenwe are " up against it " owing to difficult weather orgeographical conditions, or if we are tired, companydoes seem to " shorten the journey," but, in the ordinarycourse of events, the presence of a genial companionadds to the pleasure of a ride and, makes the time passquickly.

Dividing the DistanceIT is very easy to be dogmatic on the question of

dividing the distance which constitutes a day'sride, but the personal equation must always be bornein mind. I have often suggested that an easy way ofviewing a jaunt of roo miles is to split the distanceinto three equal parts, plus one. Thus, 33 miles in themorning, 33 in the afternoon, and 33 (or 34) in theevening, sound quite easy of achievement-as, indeed, .

they are. But this arbitrary division, all right on aper,is not of necessity the best in practice, and it is for theindividual to ascertain how best he (or she) can disposeof a century of miles. At one time I, riding badly inthe morning, would have transferred a block of themileage to the evening when, normally, I am at mybest-such best as it is 1 But nowadays the time makeslittle differen% and I employ no science in the dividingof my day's distance. I am a law to myself-whichis another way of saying that the personal equation,all-important, is allowed to function. Thus, on onerecent morning, I did 21 miles before lunch, while onthe following morning I accounted for 34 miles. Myusual evening mileage is in the neighbourhood of25 miles. As an exception I rode 44 miles after teaon a recent day. There is no perfect, or universal,method of dividing one's daily mileage. The matteris always one for personal decision, regard being hadfor one's mood _and for the conditions in which thejourney is being done.

ObservationsNOTICED during the recent (or, perhaps, still

current) beer famine: (s) The sudden andcomplete unpopularity of motor -coaches, which donot seem to be wanted anywhere. (In one place,however, a slight variation was observed, the wording ,of the notice being : " No coaches except by appoint-ment." Fancy a motor -coach having to make anappointment with a pub just as though it were ahuman being going to have a tooth out !) (2) Onepub exhibited a notice : " No beer-only pop ! "As Robb Wilton would say : " Well, of all Use things !Imagine hose a consumer of alcohol would view theoffer of a bottle of " pop " ! (3) At a pub called" Ye Olde Half-waye House," a wag had adjusted thegrim notice about the fluid famine, so that it read :

Solde Outs.." It was thus in keeping with "YeOlde " tripe 1

SANGAMO SYNCHRONOUSMOTORS. -Self-starting, exception-ally good torque ; rotor speed 200r.p.m., 200-250 v. A.C., 50 c. Consump-tion 22 watts. Size 22x2. Geared I rev.CO:min., can be reset to zero by frictiondrive from front or back. Shaft din. x1/10 to run clockwise ; ideal move-ments for making electric clocks, timeswitches, etc. Nickel -plated finish.Price 2216 each.12 to I Dial Trains to fit above spindle,per set, 216.SANGAMO SYNCHRONOUSMOTORS (as above). -Geared I rev.60 sec. Ideal movements for makingelectric dark room clocks, timeswitches, etc. Nickel -plated finish.Price 2216 each.CHAMBERLAIN and HOOKHAMSYNCHRONOUS MOTORS (En-closed Type). -Self-starting, excep-tionally good torque ; rotor speed200 r.p.m., 200-250 v. A.C., 50 c.Consumption 3 watts. Size 22 x 2.Geared I rev. 60 min., can be reset tozero by friction drive from front orback. Shaft (in. x 1/10 to run clockwise ;ideal movements for making electricclocks, time -switches, etc. Nickel -plated finish. Price 251- each.12 to I Dial Trains to fit above spindle,per set, 216.15 AMP. MERCURY SWITCHES,enclosed bakelite tubular cases, 2.1in. xyin., fitted swivel saddle, connectorblock, etc., 516 each.WIRE -WOUND NON-INDUC-TIVE RESISTANCES, 2 watt, idealfor Meter Shunts, Resistance Boxes,etc., 21 per cent. accuracy, wound onbakelite bobbins, Kin. x in. One ofeach of the following ratings, 25, 50,100, 200, 400, 600, 1,000 and 2,000 ohms.516 per lot, postage paid, quantitiesavailable.THROAT MICROPHONES, fittedwith elastic bands, 'phone plug, 15

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