SHOOTING STARS. COMETS. 53 



twenty stars have since been confirmed and extended 

 by Mr. Christie, now Astronomer Royal, in succession 

 to Sir G. Airy, who has long occupied the post with so 

 much honour to himself and advantage to science. 



To examine the spectrum of a shooting star would 

 seem even more difficult. Alexander Herschel first 

 succeeded in doing so, and determined the presence of 

 sodium ; since which Yon Konkoly has recognised the 

 lines of magnesium, carbon, potassium, lithium, and 

 other substances, and it appears that the shooting stars 

 are bodies similar in character and composition to the 

 stony masses which sometimes reach the earth as 

 aerolites. 



Some light has also been thrown upon those mys- 

 terious visitants, the comets. The researches of Prof. 

 Xewton on the periods of meteoroids led to the remark- 

 able discovery by Schiaparelli of the identity of the 

 orbits of some meteor-swarms with those of some 

 comets. The similarity of orbits is too striking to be 

 the result of chance, and shows a true cosmical relation 

 between the bodies. Comets, in fact, are in some cases 

 at any rate groups of meteoric stones. From the 

 spectra of the small comets of 1866 and 1868, Huggins 

 showed that part of then* light is emitted by themselves, 

 and reveals the presence of carbon in some form. A 

 photographic spectrum of the comet recently visible, 

 obtained by the same observer, is considered by him to 

 prove that nitrogen, probably in combination with 

 carbon, is also present. 



No element has yet been found in any meteorite, 

 which was not previously known as existing in the 

 earth, but the phenomena which they exhibit indicate 



