%^2 On Stones wbteb have fallen from, (ht Heavens. 



ance, and of their component parts, evidently fl»o\v that they 

 have all had the fame origin. If we admit, with Halley and 

 Chladnl, that, befides the large celeftial bodies, there are in 

 boundlefs fpace an infinite number of fmall maffes which 

 move about till they approach fo near a planet as to enter its 

 atmofphere, when they take fire, burft, and fall down upon 

 it ; we can explain why all thefe mafles difperfed throughout 

 infinite fpace confifl of iron, nickel, filiceous earth, and talc 

 earth, which, according to the it)gcnious experiment? ot Mr, 

 Howard, are the component parts of all the malfes which 

 have fallen from the heavens. 



But, on the other hand, great difficulties occur, ifthefe 

 flones which have fallen from the heavens be ferioufly confi- 

 dtred as bodies projefted from the moon. In confequenLSi 

 of the motion of the moon, bodies projected from it acquire,; 

 befidts their projeclile velocity, that velocity which the moon 

 has in the direction of the tangents to her orbit. If we 

 therefore take this velocity into the account, it will appear, 

 that heavy bodies projefted from the moon with a velocity of 

 8000 ftet or more per fecond, as foon as they have got to 

 fuch a diftance from the moon as to experience Icfs attrac- 

 tion from it than from the earth, would defcribe around the 

 earth a conic fe£tion pafling more or lefs through the moon. 

 Thefe conic fct^ioiis, according to the difference of the di-- 

 rc6lion and vclocitv, mav be either hyperbolas or ellipfes*. 

 In order that the bodv {hould fall to the earth, the eilipfe it 

 dcfcribes ought to be of fuch a nature that its perigeum fills 

 within the bodv of the earth, or at lead within its atmofphere. 

 The moon, therefore, muft perceptibly decreafe in fize, as it 

 would be neceflary that it fhonld throw out a great number 

 of maflfes to make fome of them reach the earth. For this 

 purpofe alfo a very lin?ired dircftion and velocity of the heavy 

 bodies would be required. And would not an infinite num- 

 ber of fuch fmall fragments move around our earth as fatel- 

 lites ? Would they not be vifible through our beft telefcopes, 

 as we know that fire-balls fometimes are of very great fize, 

 and as the obfervaliou of Ceres and Pallas has ihown that 

 bodies of a very fmall diameter become vifible to ns when 

 illuminated by the light of the fun ; or are the fliooting (lars, 

 which feem to have a cofmical origin, fuch fmall ialt Uiles 

 of our earth? Perhaps we ought to clafs among ihcfe alio 

 (he fmall pale luminous fpot vihich Schroeier faw pafs over 

 the field of his telefcope. Thefe objeftions, and others which 



♦ A prodigious velocity wou'd be required ro make a body projedled 

 frum the moon co full tu the earth m aii li^pcruola. 



arife 



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