6 



Prof. J. N. Lockyer. 



[Nov. 21, 



ordinarily seen, and as taken in the comparison of May 4, does not 

 represent the place of the brightest component of the double line, so 

 that exact coincidence was not to be expected. 



Thongh the observations are not yet quite completed, the circum- 

 stance that the line is double in both gas and chromosphere 

 pectrum, in each the less refrangible component being the fainter, 

 taken in conjunction with the direct comparisons which have been 

 made, render it highly probable that one of the gases obtained from 

 cleveite is identical with that which produces the D 3 line in the 

 spectrum of the chromosphere. 



Other observers have since succeeded in resolving the chromo- 

 spheric line. On June 20, Professor Hale found the line to be clearly 

 double in the spectrum of a prominence, the less refrangible compo- 

 nent being the fainter, and the distance apart of the lines being 

 measured as 0*857 tenth-metre.* 



The doubling was noted with much less distinctness in the 

 spectrum of the chromosphere itself on June 24. Professor Hale 

 points out that Rowland's value of the wave-length (as well as that 

 of 5875*924, determined by himself on June 19 and 20) does not take 

 account of the fact that the line is a close double. 



Dr. Huggins, after some failures, observed the D 3 line to be double 

 on July 10 ;f he also notes that the less refrangible component was 

 the fainter, and that the distance apart of the lines was about the 

 same as that of the lines in the gas from cleveite, according to Runge 

 and Paschen. 



It may be added, that in addition to appearing in the chromo- 

 sphere, the D 3 line has been observed as a bright line in nebulaa by 

 Dr. Oopeland, Professor Keeler, and others ; in /3 Lyrae and other 

 bright line stars ; and as a dark line in such stars as Bellatrix, by 

 Mr. Fowler, Professor Campbell, and Professor Keeler. In all these 

 cases it is associated with other lines, which, as I shall show pre- 

 sently, are associated with it in the spectra of the new gases. 



The Blue line, \ 4471*8. — A provisional determination on April 2 of 

 the wave-length of a bright blue line, seen in the spectrum of the 

 gases obtained from a specimen of cleveite, showed that it approxi- 

 mated very closely to a chromospheric line, the frequency of which is 

 stated as 100 by Young. 



This line was also seen very brilliantly in the tube supplied to me 

 by Professor Ramsay on May 1, and on May 6 it was compared 

 directly with the chromosphere line by Mr. Fowler. The second 

 order grating spectrum was employed. The observations in this 

 region were not so easy as in the case of D 3 , but with the dispersion 

 employed, the gas line was found to be coincident with the chromo- 



* < Ast. Nach.,' 3302. 

 f < Ast. Nach.,' 3302. 



