394 Intelligence and Miscellaneous Articles. 



in the spectroscope with the spectrum of the induction spark taken 

 in a current of olefiant gas. 



The three bands of the comet appeared to coincide with the corre- 

 sponding bands of the spectrum of carbon. In addition to an appa- 

 rent identity of position, the bands in the two spectra were very 

 similar in their general characters and in their relative brightness. 



These observations were confirmed on June 25. 



The remarkably close resemblance of the spectrum of the comet 

 to that of the spectrum of carbon, necessarily suggests the identity 

 of the substances by which in both cases the light was emitted. 



The great fixity of carbon seems, indeed, to raise some difficulty 

 in the way of accepting the apparently obvious inference from these 

 prismatic observations. Some comets have approached sufficiently 

 near the sun to acquire a temperature high enough to convert even 

 carbon into vapour. 



In the case of other comets, the author suggests that the difficulty 

 is one of degree only ; for the conditions are not known under which 

 even a gas permanent at the temperature of the earth could maintain 

 sufficient heat to emit light. 



The author states that some phosphorescent substances give spectra 

 which are discontinuous, but he gives reasons which would scarcely 

 permit us to consider cometary light to be of a phosphorescent cha- 

 racter. 



The spectrum shows that the colour of this comet was bluish 

 green. Considerable difference of colour has been remarked in the 

 parts of some comets. Sir William Herschel described the head of 

 the comet of 1811 to be of a greenish or bluish-green colour, while 

 the central point appeared of a ruddy tint. The same colours have 

 been observed in other comets. If carbon be the substance of some 

 comets, this substance, if incandescent in the solid state, or reflecting, 

 when in a condition of minute division, the light of the sun, would 

 afford a light which, in comparison with that emitted by the luminous 

 vapour of carbon, would appear yellowish or approaching to red. 



The author refers to the bearing of these results on certain co- 

 metary phenomena, and on the apparent identity of the orbits of 

 the periodical meteors with those of some comets. 



L. Intelligence and Miscellaneous Articles. 



ON STELLAR SPECTRA. BY FATHER SECCHI. 



TN one of my previous researches on stellar spectra I pointed out 

 -*■ that researches on coloured stars led us to admit a fourth type of 

 stellar spectra, the standard of which might be the spectrum which 

 I have published of the star 12561 of Lalande. Now (after having 

 completed a review of the coloured stars) I am absolutely certain of 

 this fact. This type had escaped me in my previous researches ; for 

 none of them exceeds the sixth magnitude ; and it would not have 

 been remarked without the introduction of the cylindrical eyepiece, 

 which leaves to the spectra of these stars all their brilliancy. 



