THE STUDY OF METEORITES. 431 



found to differ in composition from any known terrestrial substances. 

 The character of these indicates the complete absence of water and of 

 oxygen in any large amount from that portion of nature's laboratory 

 where meteorites are formed. Important investigations as to the gases 

 occluded by meteorites were begun by Boussingault in 1861 and have 

 been continued by Wright, Ansdell, Dewar and others. It has been 

 proved that large quantities of hydrogen, as well as carbonic acid gas, 

 are contained in these bodies, under pressure greater than that of 

 the earth's atmosphere. These investigations led further to the spec- 

 troscopic study of meteorites by Vogel, Wright and Lockyer. The 

 spectra thus obtained when compared with those exhibited by comets 

 showed striking resemblances, which have led to a growing belief 

 among scientific men in the identity of origin of comets and meteorites. 

 Lockyer has indeed pushed this conclusion to the point of believing that 

 "all self-luminous bodies in the celestial spaces are composed either of 

 swarms of meteorites or of masses of meteoritic vapor produced by 

 heat," and he draws from this many important deductions relating to 

 the origin of the stars, comets and nebula?, and the physical condi- 

 tions prevailing in them. It will remain for the twentieth century to 

 test the correctness of such conclusions, but the facts already brought 

 out have considerably shaken the confidence hitherto placed in the 

 nebular hypothesis. Another interesting result of the century 

 has been the establishment of a general similarity between shooting 

 stars and meteorites. This idea was first suggested by Chladni in 

 1798, but it has remained for Newton, Adams and Schiaparelli to give 

 it shape and proof. The general verdict of science is now in accord 

 with the belief of Newton, "that from the faintest shooting star to the 

 largest stone meteor we pass by such small gradations that no clear 

 dividing lines can separate them into classes." Moreover, the long- 

 existing belief in le vide planetaire, space filled only with a mysterious 

 fluid called ether, has been shown to be untenable. Careful records and 

 estimates have shown that 20,000,000 cosmic bodies large enough to 

 produce the phenomena of shooting stars are encountered by the earth 

 daily. The number of these bodies existing in space must be, therefore, 

 beyond all calculation, and their existence implies that of smaller par- 

 ticles in sufficient number to form a widely pervasive cosmic dust. Many 

 remarkable meteorite falls have occurred during the century. Beginning 

 with the stone shower of L'Aigle in 1803, when 2,000 to 3,000 stones 

 fell, no less than eleven such showers have been recorded. In the shower 

 of Pultusk, Poland, which occurred in 1868, 100,000 stones are estimated 

 to have fallen, their total weight reaching over 400 pounds. In the 

 shower at Mocs, Germany, in 1882, more than 3,000 stones fell. In our 

 own country about 750 pounds of meteoric matter fell at Estherville, 

 Iowa, in 1879, and several thousand stones fell over an area nine miles in 



