METEORS AND AEROLITES. 281 



Thus compelled to seek for a source beyond the limits of 

 terrestrial action, the hypothesis of lunar origin next came 

 into notice, and was discussed or advocated by philosophers 

 of much higher eminence. Wonder has been called the 

 mother of Wisdom ; and bare conjecture has oftentimes long 

 anteceded the researches and results of more exact science. 

 A fall of stones at Milan, about the year 1660, by which a 

 Franciscan monk was killed (one of three or four recorded 

 instances of death from this cause) led a naturalist of that 

 country, Paolo Terzago, to publish his conjecture that these 

 stones might come from the Moon. Another great fall of 

 aerolites at Sienna, 134 years afterwards, brought the higher 

 genius of Olbers to researches founded on the same idea, 

 which seems to have been dormant in the interval. In 1795 

 he examined the question of the initial velocity required to 

 project a body from the surface of the Moon so that it might 

 reach the earth, and determined this to be about 8,000 feet 

 in a second. The lunar theory, and the dynamic questions 

 connected with it, (which Humboldt whimsically entitles the 

 ballistiches Problem,) speedily engaged the attention of other 

 philosophers. A characteristically bold and terse speech of 

 Laplace, at the Institute, in December 1802, gave impulse 

 as well as sanction to the enquiry. It was made on the 

 occasion already alluded to, when the report of the analysis 

 of meteoric stones by Howard and Vauquelin, and the in- 

 ferences thence derived, still found an incredulous audience 

 in this learned body. 



To that of Laplace may be added the other eminent names 

 of Poisson, Biot, and Berzelius, as successively engaged with 

 the hypothesis of lunar origin ; and their respective calcula- 

 tions of the projectile force required were sufficiently alike to 

 justify the conclusion of Olbers, stated above. The argument 

 then stood, and still stands, thus. It is well known that the 

 hemisphere of the Moon, permanently opposed to the earth, 



