1868.] 



of Brorsen^s Comet, 



387 



examined the spectrum of another small and faint comet in May 1867- 

 The spectra of these objects, as far as their very feeble light permitted them 

 to be observed, appeared to be very similar. In the case of each of these 

 comets, the spectrum of the minute nucleus appeared to consist of a bright 

 line between B and F, about the position of the double line of the spec- 

 trum of nitrogen, while the nebulosity surrounding the nucleus and forming 

 the coma gave a spectrum which was apparently continuous. 



Unfavourable weather prevented me from obtaining an observation of 

 Brorsen's comet, at its present reappearance, before April 29. Since that 

 evening I have examined it on May 2, 4, 6, 7, 12, 13. As I have not 

 noticed any change in its spectrum during this time, I will put together 

 the results of my observations on different nights, in order to avoid the 

 repetition which would occur if the observations were arranged in the order 

 in which they were made. 



I tried various spectroscopes upon this object. The best views of its 

 spectrum were obtained with a spectroscope of the form already described 

 in my former papers*, and furnished with one prism of very dispersive flint 

 glass, with a refracting angle of 60°. Some measures were taken with a 

 similar spectroscope, with two prisms of 60°. 



The comet appears in the telescope as a nearly round nebulosity, in 

 which the light increases rapidly towards the centre, where on some occa- 

 sions I detected, I believe, a small stellar nucleus. Generally this minute 

 nucleus was not to be distinguished from the bright central part of the comet. 



1 











zyco 



:nsoo 



CO aitcc 



xsoo 



xaoc 



ji 



CO 







1 1 1 1 1 1 1 1 1 1 1 ! 1 1 



1 1 1 1 









1 



■ 





I 



■ 



KO. I 



r N Id 





I suspected two or three bright points in the coma. May 7, I perceived 

 a small extension of the faint surrounding nebulosity in a direction oppo- 

 site to the sun, so as to form a short tail. 



The spectrum of this comet consists for the most part of three bright 



Philosophical Transactions, 1864, p. 415. 

 VOL. XVI. 2 N 



