

On the Spectra of Comet a 1890 and the Nebula (r.C. 4058. 217 



the broadest, but they are all broad, though even in this photograph 

 they are not seen with the distinctness which is necessary for ascer- 

 taining accurately their relative character. 



The sixth line occurs where the spectrum is faint, almost at the 

 limit of this photograph, which was taken when Sirius was some 

 distance past the meridian, and we are not able to find out whether 

 this line completes the group, or whether there may not be other 

 lines still more refrangible belonging to ifc. We expect to be able to 

 determine this point, namely, whether the group ends with the sixth 

 line, when the opportunity comes round of being able to photograph 

 the star when it is near the meridian. 



The new group of six lines is well seen when the photograph is ex- 

 amined with a lens, but when the plate is placed under the measuring 

 microscope it is only with some difficulty that the lines can be ob- 

 served with the distinctness which is necessary for measuring them 

 with a fair approach to accuracy. 



For this reason, the wave-lengths given below must be regarded as 

 only preliminary, and but roughly approximate measures of the 

 positions of the new lines. 



1st Line X 3338 



2nd X3311 



3rd X3278 



4th X3254 



5th X322S 



6th X 3199 



* On the Spectra of Comet a 1890 and the Nebula G.C. 4058." 

 By J. NORMAN LOCKYER, F.R.S. Received and Read 

 June 12, 1890. 



The comet discovered by Mr. Brooks on the 19th of March (a, 1890) 

 has recently been observed at Kensington with the view of testing 1 

 the sequence of spectra which resulted from my discussion of all the 

 spectroscopic observations of comets which had been made up to the 

 end of 1888.* The orbit, however, is such that the comet has only 

 passed through a small range of temperature, and no changes have 

 been observed in its spectrum beyond the gradually increasing 

 brilliancy of the carbon bauds relatively to the continuous spectrum. 

 As I pointed out in the paper referred to, the citron band should be 

 most variable, for the reason that the brightest flutings in the spectra 

 of manganese and lead fall near it ; but, although this band has been 

 carefully observed on every occasion, it has retained the same wave- 



* ' Koy. Soc. Proc.,' vol. 45, p. 189. 

 VOL. XLVIII. R 



