90 Things not generally Known. 



Euripides, in Phaeton, terms the sun "a golden mass," that is to say, 

 a fire-coloured, brightly-shining matter, but not leading to the infer- 

 ence that aerolites are golden sun-stones. The Greek philosophers had 

 four hypotheses as to their origin : telluric, from ascending exhalations; 

 masses of stone raised by hurricanes ; a solar origin ; and lastly, an 

 origin in the regions of space, a* heavenly bodies which had long re- 

 mained invisible: the last opinion entirely according with that of the 

 present day. 



Chladni states that an Italian physicist, Paolo Maria Terzago, on 

 the occasion of the fail of an aerolite at Milan, in 1660, by which a Fran- 

 ciscan monk was killed, was the first who surmised that aerolites were 

 ofselenic origin. Without any previous knowledge of this conjecture, 

 Olbers was led, in 1795 (after the celebrated fall at Siena, June 16th, 

 1794), to investigate the amount of the initial tangential force that 

 would be required to bring to the earth masses projected from the 

 moon. Olbers, Brandes, and Chaldni thought that "the velocity of 16 

 to 32 miles, with which fire-balls and shooting-stars entered our atmo- 

 sphere," furnished a refutation to the view of their seleiiic origin. Ac- 

 cording to Olbers, it would require to reach the earth, setting aside the 

 resistance of the air. an initial velocity of 8292 feet in the second ; ac- 

 cording to Laplace, 7862 ; to Biot, 8282 ; and to Poisson, 7595. Laplace 

 states that this velocity is only five or six times as great as that of a 

 cannon-ball ; but Olbers has shown that " with such an initial velocity 

 as 7500 or 8000 feet in a second, meteoric stones would arrive at the 

 surface of our earth with a velocity of only 35,000 feet." But the mea- 

 sured velocity of meteoric stones averages upwards of 114, 000 feet to a 

 second ; consequently the original velocity of projection from the moon 

 must be almost 110,000 feet, and therefore 14 times greater than Laplace 

 asserted. It must, however, be recollected, that the opinion then so pre- 

 valent, of the existence of active volcanoes in the moon, where air and 

 water are absent, has since been abandoned. 



Laplace elsewhere states, that in all probability aerolites " come 

 from the depths of space ;" yet he in another passage inclines to the hy- 

 pothesis of their lunar origin, always, however, assuming that the stones 

 projected from the moon "become satellites of our earth, describing 

 around it more or less eccentric orbits, and thus not reaching its atmo- 

 sphere until several or even many revolutions have been accomplished." 



In Syria there is a popular belief that aerolites chiefly fall on clear 

 moonlight nights. The ancients (Pliny tells us) looked for their fall 

 during lunar eclipses. Abridged from HumboldCs Cosmos, vol. i. (Bonn's 

 edition). 



Dr. Laurence Smith, U.S., accepts the "lunar theory," and 

 considers meteorites to be masses thrown off from the moon, 

 the attractive power of which is but one-sixth that of the earth; 

 so that bodies thrown from the surface of the mocn experience 

 but one sixth the retarding force they would have when thrown 

 from the earth's surface. 



Look again (says Dr. Smith) at the constitution of the meteorite, 

 made up principally of pure iron. It came evidently from some place 

 where there is little or no oxygen. Now the moon has no atmosphere, 

 and no water on its surface. There is no oxygen there. Hurled from 

 the moon, these bodies, these masses of almost pure iron, would 

 flame in the sun like polished steel, and on reaching our atmosphere 

 would burn in its oxygen until a black oxide cooled it ; and this we find 



