24 BULLETIN 94, UNITED STATES NATIONAL MUSEUM. 



The scientific mind was, however, slow in accepting these proofs. 

 Fortunately there occurred about this time (April, 1803) a shower of 

 stones, upward of 3,000 in number, in the neighborhood of L'Aigle 

 near Paris. The circumstances of this fall were fully investigated 

 under the auspices of the French Academy of Sciences, the report of 

 which was of so conclusive a nature as forever to set at rest all doubts 

 concerning their extra-terrestrial origin. 



PHENOMENA OF FALL. 



The fall of a meteorite is usually accompanied by noises vari- 

 ously described as resembling the fire of musketry, cannonading, 

 or even thunder. If the fall takes place during periods of dark- 

 ness it is also accompanied by a flash of light and followed by 

 a luminous rocket-like trail. These phenomena are due to the 

 rapid passage of the objects through the air, and the consequent rise 

 in temperature which is sufficient to produce fusion of the outer 

 surface and even ignition, thus giving rise to the thin, dark, glass- 

 like crust which is found coating all stony meteorites. The time of 

 passage through the atmosphere is, however, too short to permit the 

 heat to penetrate to great depths, and nearly all meteorites are quite 

 cool, or scarcely warm, on reaching the surface of the ground. It is 

 to the sudden rise in temperature and pressure of the atmosphere, 

 too, that is due the breaking up of a meteorite and its reaching the 

 earth as a shower of fragments rather than a single individual. 



We have little to guide us in estimating the speed at which a me- 

 teorite reaches the earth and its consequent power of penetration. 

 The velocities as given by various observers vary between 2 and 45 

 miles a second. These last, however, are the initial velocities, the 

 velocities possessed by the meteors on entering our atmosphere and 

 while still at considerable altitudes— in some instances 50 or 60 

 miles — and which become very materially reduced by atmospheric 

 friction long before reaching the earth. Indeed, from the calcula- 

 tions of Schiaparelli and others, it is commonly assumed that a 

 meteorite reaches the surface at the speed of an ordinary falling- 

 body. A. Herschell, as quoted by Flight,^ calculated the velocity of 

 the Yorkshire (England) meteorite at the time it reached the ground 

 as but 412 feet a second. The Guernsey (Ohio) meteorite was esti- 

 mated by Prof. E. W. Evans ^ to have reached the earth while travel- 

 ing at a speed of 3 or 4 miles a second ; that of Weston, Connecticut, 

 while at a height of some 18 miles, was estimated by Prof. Bow- 

 ditch^ to have a velocity of 3 miles a second. Newton* calculated 



1 A Chapter on the History of Meteorites, 1887, p. 219. 

 «Amer. Journ. Sci., vol. 32, 1861, p. 30. 

 sMem. Amer. Acad. Arts and Sci., vol. 3, 1815, p. 213. 

 *Amer. Jour. Sci., vol. 33, 1862, p. 338. 



