746 KANSAS CITY REVIEW OF SCIENCE. 



our brief limits, and without the use of technical language, we will endeavor to 

 outline some of the more important results of observation and reflection upon 

 this subject. We shall be obliged to draw freely from the results elaborated dur- 

 ing the last fifty years by Bessel, Winnecke, Bond. Newton, Zoellner, Bredichin 

 and many others, without reference to individual authorities or digressions upon. 

 rival theories and claims. 



METEORS — OFFSPRING OF COMETS. 



§ I. About twenty years ago it was proved that certain annually recurring 

 displays of meteors are due to swarms of small bodies, which revolve about the 

 sun in elliptical paths, so situated in space as to encounter the earth at nearly the 

 same time in each succeeding year. These paths or orbits were found to be 

 idenJcal in some cases with those of certain well-known comets. The conclu- 

 sion seemed irresistible and is now accepted, that shooting stars, or meteoroids, 

 are simply the offspring of disintegrated comets. 



Most Hkely, aerolites (large meteors) which sometimes reach the surface of 

 the earth, are of the same origin. These bodies usually enter our atmosphere 

 with velocities (relative to the earth) tanging from twenty to forty-five miles per 

 second. In consequence of the inconceivable heat which would be generated 

 by such contact — manifested by the fiery train they leave behind — the smaller 

 meteors, however dense, would be at once converted into impalpable vapor. 

 Only the larger ones could survive the tremendous encounter, and reach the 

 earth. Still others, composed of more fusible substance, though very large, may 

 be unable either to overcome the mechanical resistance of the air, or the trans- 

 cendent heat produced. Furthermore, that fiery ordeal must strip aerolites of 

 all volatile matter and leave only refractory substances behind. Hence, analysis 

 of meteoric stones might give us an idea of the real composition of comets which 

 would be totally misleading; just as the ruins of a house, destroyed by fire, 

 would be no index of the chemical composition of all the material it contained 

 before the disaster. 



TESTIMONY OF THE SPECTROSCOPE AND POLARISCOPE. 



§ 2. The Spectroscope (light analyzer) rather reluctantly yields some testi- 

 mony as to the chemical and physical nature of comets. It seems to show that, 

 the nucleus is a solid or liquid incandescent (at a glowing temperature) mass. It 

 proves quite conclusively that the matter surrounding the nucleus contains hydro- 

 gen and carbon in one of their numerous compounds. The flame of the Bunsen 

 burner, which contains one of the compounds, shows a spectrum (light analysis) 

 which is very similar to, if not identical with, that observed in comets. Some 

 observers have reported that these elements give evidence of their presence 

 in the tails of comets at considerable distances from the head. If so, we must 

 suppose the attenuated matter of the tail to be self-luminous. This may be attrib- 

 uted to some form of electrical action ; since, considering the low temperature 

 of space, it cannot be due to incandescence produced by ordinary heat. 



