52 



Mr. J. S. Ames on some Gaseous Spectra. 



spectrum of hydrogen has been shown by Hasselberg * to be 

 due to this gas, and the wave-lengths of many of its lines have 

 been measured by him. Cornu does not say whether he 

 observed the secondary spectrum as well as "the stellar 

 series " or not, but I judge from a chance remark that he did. 

 I was entirely unable to get the stellar series by itself, although 

 my hydrogen was pure I am confident, and I varied the tubes, 

 the current, the vacuum, and the exposure. I also introduced 

 large condensers without any noticeable change. Cornu's 

 plates were 5 centim. long, and one was sufficient for the 

 entire hydrogen spectrum from G f to 6. His time of expo- 

 sure was often three and a half hours. My plates were surely 

 more sensitive than his ; and, as the secondary spectrum 

 includes the stellar series, I think the lines observed by him 

 appear on my photographs, especially as he speaks of the 

 " brilliant rays " coming from his tube, in contrast with the 

 nebulous lines in the spectra of the stars. If his lines had 

 been faint and hazy, I might suppose my dispersion too great. 

 The wave-lengths of the most important hydrogen-lines, as 

 measured on my plates, with their intensities, and the corre- 

 sponding wave-lengths as given by Hasselberg and Cornu are 

 as follows : — 



F 



G 



0(6563-042). 

 5084-9 

 5055-2 

 5013-15 

 4973-3 

 49288 

 4876-1 

 4861-49 

 4838-3 

 4797-9 

 47640 

 4719-2 

 468395 

 4634-15 

 4580-1 

 4534-8 

 4498-75 

 4461-1 

 4447-85 

 4412-35 

 434066 

 4212-65 

 4205-2 

 4195-9 

 417725 

 4171-35 



Hydrogen. 



6 

 6 

 4 

 20 

 4 

 4 

 3 

 5 

 5 

 6 

 4 

 2 



4 

 5 

 3 

 5 

 15 



5084-56 

 5054-22 

 501221 

 4972-51 

 4927-95 

 4875-23 

 4860-60 

 4837-31 

 4796-81 

 4762-53 

 4718-33 

 468300 

 4633-10 

 4579-44 

 4533-72 

 4497-53 

 4460-62 

 4447-24 

 4411-75 

 434006 

 4211-83 

 4204-39 

 4194-98 

 4176-47 

 4170-66 



Cornu. 

 4339-5 



* Mem. de VAcad. imp. St. Petersb. xxx. p. 7 (1882), xxxi. p. 14 ; 

 Bull, de VAcad. imp. St. Petersb. xi. p. 203 (1884). 



