395

COMMITTEE ON SCIENCE AND THE 2~RTS.

Report on U.. 5: Government ~leamer " V i r g i n i a , "

The Committee on Science and the Arts, constituted by the Franklin Institute of the State of Pennsylvania, for the promotion of the Mechanic Arts, who, agreea- bly to request, witnessed, by sub-committee, the experiments tried on the Dela- ware river with the U. S. Government Steamer "" Virginia," REroaT:--

That they understand that the hull of this vessel was built by Win. H. Brown of New York, and that her dimensions are as follows:-- Length on deck, 147 feet 6 inches; breadth, 24 feet 3 inches; depth, 15 feet 10 inches; tonnage, 403~§ tons; draught of water, 7 feet forward, and 7 feet6 inches aft. Shewas formerly propelled by two paddle Wheels, of Aldrich's patent, similar to the "Hunter submerged wheel," but working vertically. The external diameter of these wheels was nine feet nine inches; each having 16 paddles of 20 by 14 inches. In place of these wheels, the "Virginia" has been recently furnished with two " L o p e r propellers," worked by the same engines which were used to drive the original paddle wheels. These propellers are each eight feet in diameter. The two engines have each 24 inch cylinders, and 30 inches stroke.

The Committee have no knowledge of the relative speed of this vessel when she was worked by the above mentioned paddle wheels, and are therefore unable to make a comparison between her former and her present performance. They can only state the result of their observations made on an experimental trip with the "Virginia ," on the morning of the 1 l th September, 1847, after the paddle wheels had been removed, and the Loper propellers substituted.

Leaving the wharf, at Dock street, the vessel proceeded down the river, passing the south side of the large ship-house at the Navy Yard at 10 h. 20 m. 47 s., and being opposite the north side of the lower wharf at the Point House at 10 h. 34 m. 47 s.; which makes the time of passing this distance (2"19 miles by coast survey) exactly 14 minutes. Continuing her course, the vessel was opposite the flag-staff at Fort l~diiitin at 11 h. 10 m. 50 s., giving a running time, from the Point to the Fort, of 36 m. 3 s.--or, from Navy Yard to Fort, 50 m. 3 s. The distance from the shears at the Navy Yard to Fort Mifflin is, by coast survey, 7.16 miles. During the downward passage,the engines worked very uniformly, making 54 revolutions per minute; it was made against tide, but with a moderate breeze in our favor.

Below the Fort, the experiment was tried of putting the vessel about, by stopping one of the propellers, and also by reversing its action. The first half turn, by which the course of the vessel was reversed, and her head brought so as to be directed up the river, on an exactly opposite course to that pursued immediately before being brought about, was accomplished in 4 m. 30 s.,'bringing her head round against a stiff breeze from the N . E . The next half turn, by which the head of the vessel was brought to her original course down the river, w a s

396 t~ranklin I~slilule.

made in exactly two minutes, by the action of the propellers alone. This experiment was repeated, and her head again directed up the river, in 3 m. 2 s.; while the next half turn, to bring her again upon the downward course, occupied 2 m. 14 s.

In returning up the river the tide was favorable, but the passage was made against a stiff breeze from the N . E . From the flag-staff at Fort Mifflin to the Point House wharf, the run was made in 29 m. 17s., and from the Point House to the Navy Yard in 12m. 20s . - - total time, from Fort to Navy Yard, 41 m. 3os.; the engines making 50 revolutions per minute. The Committee had no means of ascer- taining exactly, for themselves, the pressure of steam employed; but were informed that it was 60 pounds to the square inch.

By order of the Committee, WILLIAM HAMV.TON, Actuary.

PhiTadelphia, Nov. 11, 1847.

Report on J. H. Schomacker ~ Co.'s Pianos.

The Committee on Science and the Arts, constituted by the Franklin Institute of the State of Pennsylvania, for the promotion of the Mechanic Arts, to whom was referred for examination an Improvement in Pianos, invented by Messrs. J. H. SCHOMACKER & CO., of Philadelphia, Pennsylvania, REPoaT:--

That they have examined the application to pianos of the inventions lately made and patented by J. H. Schomacker & Co., of which the following is a brief description :

The sounding-board, in these pianos, is constructed so as to be detach- ed from the sides of the Instrument, resting oil props, or supports, which are secured to the bottom of the case; one end of the sounding-board being made with a return, so that its whole length is virtually increased. This construction frees it entirely from the injuries which it would re- ceive from changes in the form of the case caused by the strain of the strings, or from the usual shrinking and warping of the wood used in construction, and gives it the fullest opportunity to aid in the vibration consequent upon the sounding of the string.

The result of their.examination, which has been carefully made, is, that Mr. Schomacker has, by his detached sounding-board, attained, in the tone of his pianos, a much greater degree of sonorousness and resonance than the Committee have before observed in other instru- ments of the kind. They are also of opinion that these pianos will be more durable than those made by the old principle, and that the in- ventor is deserving of much praise for introducing this improvement, which will doubtless accelerate the perfection which these instruments are gradually attaining.

With regard to the patent arrangement for candle-sticks, on the music-board, the Committee believe that it is a very convenient ar- r a n g e m e n t - n o objections can now be raised as to the danger of their