Determination of the Wave-lengths of the Hydrogen Lines. 35 



which agrees very closely with the wave-lengths of the three lines 

 Ha, Hp, H y given by Eowland. No correction to the formula has 

 been deduced, as only a small one is indicated, and it is desirable to 

 use a larger number of lines of reference than has been employed in 

 this investigation. The wave-lengths were determined from each series 

 of measures separately, and from the accordance of these the probable 

 -errors of the resulting determination of wave-lengths lie between 

 ± O'Ol and ± 0*02 of a tenth-metre for the different lines. 



Hydro - 

 sen 

 line. 



Int. 



n. 



Observed 

 wave- 

 length. 



! 



Wave- j 

 length by 

 Baimer's 1 

 law. 



Diff. 



Bemarks. 







5 



40 



6 



4101 -88 



•907 



-f '03 



Only measured on one photo- 

 graph. 



£ 



40 



I 



3970 -229 



•241 



+ -012 





I 



60 



8 



38S9 '101 



•216 





Helium line at 3888*785 not 

 separated. 



n 



40 



9 



3835 *540 



•oo0 



+ *010 





& 



30 



10 



3/98 0o7 



•063 



+ "006 





L 



30 



11 



3770 -765 



•794 



-i- '029 





K 



25 



12 



3750 322 



•315 



— '007 





A. 



18 



13 



3731 -565 



•531 



— "034 



Touching Fe line at 3735 *014. 



t* 



18 



14 



3 / 22 "060 



•101 



+■ '041 



V 



16 



15 



•"> -7 i o . -| f\(\ 



3712 109 



•133 



+ "024 





■ t 



16 



16 



3703 981 



•015 



+ -034 





a 



15 



17 



3697 '283 



•313 



+ -030 







13 



18 



3691 -670 



•717 



'+ '047 





P 



11 



19 



3686 -950 



•992 



+ -042 





<r 



9 



20 



3682 954 



•967 



4- -013 





r 



7 



21 



3679 -483 



•514 



+ -038 





V 



6 



22 



3676 -568 



•525 



- 043 



f 3676-457 Fe Cr 1 probably 

 t 3676-698 Co J interfere. 



* 



4 



23 



3673 914 



•920 



+ -006 





X 



5 



24 



3671 '574 



•638 



+ -064 



Probably Zr 3671 '412 inter- 













feres. 



+ 





25 



3669-595 



•625 



+ -030 





w 



! 



26 



3667 -891 



•843 



- -048 





a! 



2 



27 



3666-185 



•256 



+ -071 





! « 



4 



28 



3 )64-770 



•838 



+ '068 



Partly due to Y at 3664-760. 



1 l> 



1 



29 



3663 -565 



•553 



- -012 



5 



30 



3662 373 



•418 



+ -043 



Mainly due io Ti at 3662 -378. 





1 



l " 



31 



3661 -475 



•330 



- -095 



Possibly 6661 '509 Fe inter- 

 feres. 



