Some Thoughts concerning the Sun and Moon, When Near the Horizon, Appearing LargerThan When Near the Zenith; Being Part of a Letter from James Logan, Esq; To Sir HansSloane, Bart. President of the Royal Society, &c.Author(s): James LoganSource: Philosophical Transactions (1683-1775), Vol. 39 (1735 - 1736), pp. 404-405Published by: The Royal SocietyStable URL: http://www.jstor.org/stable/104048 .

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SX. Some Thoughts co cerrst22g- the Sun agd Moon, qvbex nevr the torzo-n} appearigg larger than rhetz near the Zenith; bei^g

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tPart of a Letter frorz James Logan, EAq; to Sir tSans Sloane) Brt. EPreJ gent of the Royal Society, @a.

* 8 * TtuitaoGeEplDia, Sept 20. I73f.

T T may, perhaps, be needlcSs now to add any thing in Confirx:latioll of D-r. AWallis s Solution (Xee thefe

granJaSiogs} 1Q I87.) of the Sgn and Moon>s aF pearing So much larger at rifing or WettingX than whell ill a greater Altitude; tho' fome have very abfillrdly ficill gone on to account tor it from STa. pours, which I remembcr was ginZen mc in my Youth for thc trut CauSe of it, 'TJis truey indeed) that iis tllefe Vapours, or the Attnofphere, aIon-e, that make thoge Bodies, wl;ien uery near to the HonzJny ap pear in a rpheroidal Forlz7 by refraXting, and there by raifing (to ;Sight), the lower Limb more than the

pper, yet tllefew can be no CauSe of the other. The Sgn ard Ainon, eacll fubtellding about half a. V gree, appear in vlle M¢ridian of tslle Breadth of eiglut or tell inches, to foune Eyes more, and to others lefs; and in the Horizoa to be t:wo or three Foots mo;re or lefs, accoldilag to the Extent of Ground they are Seen over: But if one can have an Oppor tunity, as 1 have here frequently had} of fecing the Sgn rife or fet over a fmall Emincnce at tlle Dif tanc.e a£ a Mile os two w-ith tail Trees on it lland-

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[ 4°S ] ing plttty clofe, as is uEual in AItood-s svitllout U£E- derwoodX his Body will then appcar to be ten or twelve FOOt ill Brcadth, according to the DiAance and CircumRances oif the Trees he is Ween through; and where there has been fome thin Underwood, or a few Saplings} I have obferved that the 5M4n fetting red, has appeared through them like a large extenfive Flame, as if fome Hcsfe wcre on Fire beyond them. Now the Reafon of this is obvious, faez-* that being well acquti4Wd with Trees, the Ideas of thc Space they take up are m a Martner Ssyd, and as ze of thoks Trees febtends- an Angle at the Eye, perliaps not. exceeding two or three Seconds, and-would fcarce bt diPringui{hable} were it not f<9r the firong Light behiad themX the Sn's Diameter of aboue thirty Mi- nlltes talies in feveral of them, and therefore will n3turally be jlldged vafily larger. Hence 'eis evident,, that thoSe Bodies appea- greater or leSs, azording to the Objeds stgrpofed or taken irl by the Eyc on. viewing the And- to this only is ehat Phxno- menon to be imputed.

I am fenfible this Method of arguing is not news yet the ObServations here given may probably tend £0 illullrate the Cafe beyond what had been ad- wanced QSl. thc Subjedc. * * *

F I N I &e

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