O. C. Lester — Oxygen Absorption Bands. 153 



Indications that the first A band is continued beyond the 

 last strong pair are not lacking though they are not so strong. 

 The other groups are too faint for corresponding lines to be 

 observed in them. 



The geometrical relations of both lines and bands are clearly 

 seen in Plates III and IV. 



In most spectra it is the vibration numbers which are sub- 

 ject to regular laws rather than the wave lengths, but in this 

 case it makes little difference so far as Deslandres' first law is 

 concerned, which is taken. The first law is but a rough 

 approximation, as is shown by the following application to the 

 second series of the second band of B. The constant b is cal- 

 culated from the sixth line. 



-7T calculated. Diff. 



A 



14526-27 

 524-84 

 520-53 

 513-36 

 14503-33 

 490-42 

 474-65 

 456-00 

 424-49 

 319-67 

 406-26 292-92 



The accuracy of the measurements would allow a variation 

 of only a few hundredths in the last column. The fact is, 

 Deslandres' constant b is not really a constant, at least for this 

 spectrum, as the following values of b, calculated for the dif- 

 ferent lines of the above series, show : 



— observed. 



A 



14526-27 



520-15 



513-49 



506-29 



14498-65 



490-42 



481-70 



472-45 



462-72 



418-53 



o-oo 



+ 4-69 



+ 7-04 



+ 7-07 



+ 4-68 



o-oo 



— 7-05 



— 16-45 



— 38-23 



— 98-76 



— 123-34 



6*12 when n = 



1 



b = 



= —1-098 when 



n — 7 



3-195 " 







— 0-993 



a 



2-22 " 







— 0-911 



a 



1-726 " 







— 0-846 



u 



1-434 " 







— 0-792 



a 



1-238 when n = 



6 





— 0-748 



— 0-710 when 



n = 13 



iations of b are 



: the 



same 



for all the bands, exc 



The 

 that for the second band series the initial values are always 

 larger than for the first. Also, the values of b for homol- 

 ogous lines of the same band series are nearly constant. 



If the values of b for any series are plotted as ordinates and 

 the values of n as abscissae, curves are obtained which at once 

 suggest a much better law. 



