THE TWO COMETS OF THE YEAR 1868. i8l 



strange circumstance that an astronomer who had 

 analysed the structure of a body millions of miles away 

 from the earth, should take into his hands and subject 

 to chemical analysis a fragment which had once in all 

 probability belonged to a similar comet! 



In conclusion, I must notice that there has been a 

 remarkable absence during the past few years of those 

 brilliant and long-tailed comets which alone seem 

 calculated to afford the spectroscopist the means of 

 answering some of the difficult questions suggested 

 above. The tail of Winnecke's comet was too faint to 

 give a visible spectrum. In fact the comet itself was 

 only just visible to the naked eye. When a blazing 

 object like Donati's comet or the comet of 1861 comes 

 to be subjected to spectroscopic analysis, we may hope 

 for an amount of information compared with which 

 that hitherto obtained is probably altogether insig- 

 nificant. 



From Frazer's Magazine for February and June 1869. 



COMETS OF SHORT PERIOD. 



IT is related by Apollonius the Myndian, that the 

 Chaldean astronomers held comets to be bodies which 

 travel in extended orbits around the solar system. 

 ' The Chaldeans spoke of comets,' he says, ' as of tra- 

 vellers, penetrating far into the upper celestial spaces.' 

 He adds, that those ancient astronomers were even able 



