572 



Prof. E. 0. 0. Baly on Light 



25 



26 



27 



Second Series. 





First Series. 





-^ 







1/A. 



\ calc. 



\ obs. 



X caic. 1/A. 



i 389-57 



25669 







389-93 



2-5646 



2-5636 





390-28 



2-5622 



2-5608 



2-5608 39051 



390-63 



2-5599 







391-00 



2-5575 







391-36 



2-5552 







39172 



2-5529 







) 392-07 



2-5506 



2-5520 





392-43 



2-5482 







392-78 



2-5460 



2-5469 





393-13 



2-5437 







393-50 



25413 



2-5425 



s 



393-86 



2-5390 







39422 



2-5367 







r 394-57 



2-5344 



2-5352 





394-93 



2-5321 



2-5311 





395-28 



2-5299 





2-5288 395-45 



395-63 



2-5276 







396-00 



2-5253 



2-5262 





396 36 



2-5230 



2-5235 





u 



12 



The justification for the correctness of the calculation does 

 not rest on this agreement so much as on the facts that 

 Sleator has observed no more lines than are obtained by 

 the use of the formula, and that the average difference 

 between the observed wave numbers of his consecutive 

 lines is just equal to that given by the formula. In view 

 of the fact that the whole calculation is based onlv on the 

 frequency differences 7'5xlQ 10 and 1' 7301 x 10 u first 

 obtained by Eucken, and the atomic frequency of oxygen 

 obtained from the absorption-system of sulphur dioxide, 

 it may be claimed that these results afford a somewhat 

 striking confirmation of the theory of the system of 

 absorption-lines shown by a substance between the limits 

 13 fi and 02 jjl. 



Sleator's measurements of the region between 5*02 fi 

 and 6*85 /x do not reveal such a complexity of absorption- 

 lines, and it is not worth while therefore to calculate the 

 frequencies of all the lines which should appear in this 

 region. It will be sufficient if the central frequencies of 

 the two series of sub-groups are calculated and compared 

 with the observed values. The central molecular fre- 

 quency of the band as already stated is 6*1326 x 8 X 10 12 

 or 4*90608 X 10 13 , and therefore the frequencies of the 

 central lines of the first series of sub-groups will be given 

 by 4-90608 x 10 13 ±m x 1-7301 x 10 12 , and those of the second 

 series by 4" 90608 x 10 ls ±n x 7 5 x 10 11 , where m and n equal 

 0, 1, 2, 3, etc. In Table II. are given the wave numbers 



