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SCIENCE. .

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Rhannu

SCIENCE. TO THE EDITOR, OF TirE C, A'Ti'E & GUARDI AN. Sjit. — In your Jiiurtial of Saturday, Jan 27, your correspondent I) enquires, "Why a hall, or other -olid body; dropped from a balloon at a hiyh eleva- tion will meet the earth in a perpendicular line from lIip. ballooa at the period of separation from it V In ausweriuur this question, let us consider the balloon, according to your correspondent, stationary. If then a hall be dropped from it, file ball will meet the erti-tb in a time depending on the alt itude if this be 3uan feet) file descent ill be the square root of 3000-16, or V 187,5 = 13,693 secot.ds; for fulling bodies obey this law, namely, as the squares of the times of fullinsj: and, as your correspondent state*, I liat 1, tile bull, iu is descent, travels at the rate of 120i) feet per minute, and would come in contract with the earth ill two minuIPs and all half." It is necessary to explain the rate for falling bodies. In the 1st second the ball falls I ii Ft. 2nd' (2 x ■>) = 4 & 4 x I C) 6J it. 3rd (3 3) = 9 & 9 lô = 114 (t. 4th (4 x 4) = 16 &16 x 16 = 25Gft.&c. It is thus found that 3030 feet = (13,693 13,093) x 16. The spaces fallen through are, as the iiiiin- tiers 1, 3, 5, 7, 9, &e. for each succecdiug second. which is evident from the calculation. I know not how I) derives his rllle of 1200 feet iu a minute, for a body fallill to the earth from any altitude. The time then of the balls reaching the earlh, from the height 3000 teet = 13,693 seconds and now we will explain by what law in physics it is so. The earth revolves from west to east, carrying the air or atmosphere wiili it, just as it carries the ocean or the rivers on its surface, and this respirable fluid (the aii) is a material substance, although of a very subtle nature, being to its pretty much what the water is to fi-hes they are buoyed along as well as irquatic birds, reposing on the bosom of the waters, iusensible to the diurnal and annual motion of the earth -so it is %vith bodies in the air. The bdlloon has tlie motion ofoui- plauet, conveyed to it by the atmosphere and the compound motion (the diurnal and annual path round the sun) are no Inore fell by the aeronaut, or the birds on wing, than is this same motion felt hy navigators, aquatic birds, or fishes. Were it otherwise, or that the eartli cut through the air, as we do in travelling, the result would be destruction to animal and vegetable life. The constant and rapid change of almospheric in- fluence would cause sterility in all climes, and no animals could endure the effects of the velocity with which they must come in contact. When we travel rapidly we are at once sensible of its effects; but assume that the air is not carried with the earth, as part ol its covering or appeudag", we encounter this dilemma: uieri, aud all other animals, and vegetable produc tions, must be rushing through the medium at the rale of 600 mil-es au hour in our latitude for diurnal, and 68,0;)0 uii'es per hour for the orbital motion. Migratory birds travel distiiievs; the passenger pigeons (Columbce migratorine) pur- lIue theIr wi:ralatiot1"J from Hud..ou'g B.IY as ('II' south as the Gulf of Mexico, at the rate at 60 or 70 miles an hour; they travel in vast flocks along the desert and illimitable air," and extraordinary flights they are; but from the organic structure of the feathered race, ihey can meet the air and make w..y where other animals would he destroyed; but let the earth cut through ttie atmosphere or leave it behind ill its double motion,could tliese same tenants of the air then make way ? for whilst they jouruied (>0 or 70 mile* from west to east, the earth would travel miles, how then could they reach their destination? it is needless to answer the ques- tioll. 'I'lie watl(lc-t'i:ig ali)it(ross (Ditnte(fil from lis peculiar air cells, intervening between Ihe muscles and skin, in addition to the vast spread of its wing*, ^10, 11, or l2teei) cuu so diminish its specific gravity, thai it is enabled tojloat in the air, as a fish does in water, This extraordinary bird has been seen suspended in the samei-pot motionless tor many seconds; if the earth kll, or cut through the air, the bird could not be seen after the lapse of a few seconds. The earlh would have out-travelled him, at the rate" of about IS miles per second. So with the -balloon I have see,, this noble exhibition of human skill and daring ascend majestically not moving (except with slight oscillations) to one side or the other, till it had attained a certain altitude. Where would ihe balloon have been, during this oil any other principle than that the mr or atmosphere was attached to our earlh, aud moved with it, as do the rocking billows or the ocean itself? The balloon has been iu sight for a considerable tune, and such a speck in the heavens would be invisible almost instantei, if we moved w iih our accustomed velocity, and the balloon partook not of the same velocity, But the earth does not leave the balloon, or the air they partake of her motion, varying oely as the allitude of the object. The ball let tall hCls the same motion impressed upon it, and we shall presem ly see how it reaches the eartli- Again, in estimating the power of winds they are classed according to their eil'ects, agreeably to this table, l'ronnrtif'l!1al force on a -1 Miles an hour. square to at in lbs. Winds, weight. 15 .V.V 1107 ■••• L>'isk Glle' 3"-> 4,4 -HJ ) „ 35 «,()•>: S •"•Higrh wind. 50 12,300 ,to,-in. 100 4U,JO A hurricane. Somc of us have doubtless witnessed these various w inds and their consequences—disastrous to life and property; but. Compare the hui rieane to the effects of earth's rushing through the air, and we can then imagine what would ari>e from 6S0 times this p iver bt iug exercised on the surface of the globe. Under such circumstances we must have a new order of things, a fresh adaptation through nature. Repro- duction could never go on • desolation would every where present itself and chaos would come again Birds of prey (the vulturidce especially) build their nests on the pinac^es of the highest rocks: they soar to immense heights, and from these, eminences descry their prey on land and sea; their desceut is astonishingly rapid, but in a few seconds if the earth were not accompanied with the- atmosphere, the prey would have vanished from these r-.iptoviul birds, and instead of pOllucing upou it direct from their aei-ial the prey would have travelled miles away, (la in every second of lime). But the atmos- phere belongs to the earth, is moved with it; and! all objects living or otherwise when in the air par- take of the earth's iliotio", iu the same manner that we partake of the motion of a ship or carriage. Birds, and aeronauts ill, their excursions are carried round with the motion of the globe; the only difference is, that the higher they are the greater is the velocity with which they move, a sub- ject we shall speuk of preseutly. Once for all, we inay consider our atmosphere as a vast envelope to the earth both partaking of the same motion which is communicated to every object within range; auy other hypothesis must not only reject all the physical data we are as yet furnished with, but set at nought the well-known principles of projectiles and flling bodies, on which enough has been written by philosophers and men of science tested by experiments, to prove that the eai-ti) and the air, or atmosphere, are borne aluli,, witil the same velocity, varying according to its altitude. Dr. Hultou says, in his dictionary, The atmos- phere surrounds the earth to a considerable height, partaking of all its mutionst both aunuai and diurnal," But although to our senses the fall of the bod »• from the ballowi is a perpendicular line, in reality it is not so, for the earth has travelled jn its diurnal motion 40 miles eastward iu'2 £ minutes, or 3 62 miles in the 13,693 seconds, besides z58 miles for the arbital motion, together above MO miles in 13,693 secotids, and tlii.,4 distance is passed over by the ball from the ballou in the time named in a vast s,,eep or,curve line (iiisen,ible to us oil the caitli, impelled by its motion) called the parabolic curve, the laws of which are in the ctfuic sections. Birds having the same motion impressed oil them must always perform their flights' and d<SCeiH8iu this well-known curve, the parabola. I With resp-'ct to the ball thrown across tho deck o! a ship. D. says, it will cross at right angles true enough, i! the ship be at rest, and Ihe same would happen if thrown by a person on shore, the ship b inj at rest. Were the ship movijtg, Ihe ball would cer- tainly pass to the opposite side, aud arrive at the same point in the ship as if at rest—but the ball although describing a right angle to all appearance by those on board, (having (he motion of the ,ship) would not iu fiict describe a right angle but the line of a diagonal ot a parallelogram irising from the compound force given to it one the moving of the sh;p, the other the throwing across the ball. This i, a,i(I wzi-, illu(Iod t,) afiiotigsi other subjects some weeks since, in' yutit- Should the ship move to tjie east, and tb- ball h. thrown to the hortb, the line %vi I be it) it direc- tion but how many points to the one or other must depend on the rate of sailing, width of dec! &c. ■ 1 I remain, Sir, Yours very obediently, G. L. TvknioTtvE ENGINT.S, &C.—At a meeting ol the of C'ivil a paper on Locomotive Engines, by Edward Woods, was read. Ibis paper contains an account of the alterations which were soon found necessary in tin- fir-t engines used on the Liverpool and Manchester Railway. I hese consisted principally iu strength- ening every part of ilit? engine, and the consequent increase iu the we:giit was such that it became ne- cessary to re-lay the whole line with stronger rails, aud, as a temporary provision, to add -a third pair ol wheels behind the fire box. The author then de- tails certain necessary conditions iu the structure of locomotives, aud the means adopted to obviate the rocking motion and the unsteadiness arising from lateral undulations. With respect to the objections urged against the use of six-wheeled 'carriages, he ohserve. that the adhesion, though less, is sullicteni aud that the additional weight does r.ot exceed two hundred weight,or produce a diminution in traction amounting to more than one -two-hundredth of ihe whole; and tlpit the additional strain and friction on passing curves fIIay be enlirely obvialed. 11,. then describes IlIe distribution of the whole weight of the engines o:i the wheels, which weight on the average, amounts to eleven and a half tuns. A paper on improvements iu water-wheels, by Isaac Dodds, was then read. The author suggests the adoption of two air vessels, forming the sides or water guides to the wheel, by which tlie wheel should be raised or lowered with the view of lessen- ing ther evil produced by the back-water. These ai.. ves.c! heill! p:-op,.rly ,llast"r!; any required dip may be given to the wu«h-boards aud Ihe race is so adapted that the dam head may be raised in the same proportion as the back-water.— A thenceum. M. CJMMAUD-—M. Gaimard lins been ap- pointed, by the French Government, to a new scien- tific expedition. Denm irk, Sweden, and Norway, are to be the scenes of his researches; and he is particularly desired lo bring back specimens of the rocks of Sweden and Norway, a series of trilobites, fragments of the rocks of Lapland, skeletons of the Narwhal and the elk, aud the heads of bears Athenaum. making mineral*, has submitted to the Academy of Sciences some stalactites of carbonate of lime, which have been pi-otiticeit iii a itiuiitli he liii- also succeeded in making microscopic glasses of melted rock crystal, which answer perfectly well, and magnify 2j[) times.—Athenttuni.

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