Note on the Yellow Helium Line. 



I'.V A. .St.C. DUNSTAN AND M. E. KICE. 



The published results for the distance between the two compo- 

 nents of the yellow helium line (5876) are not concordant; and 

 further seem to indicate that the distance is greater for solar helium 

 than for that contained in a vacuum tube. Thus Runge and 

 Paschen (Nature, June 6th, 1895) using a Geissler tube find for 

 the wave lengths of the two components 5875.883 and 5876.206 

 Ang. units, the latter being the weaker line. Mohler and Jewell 

 (Astrophys. Journ. 3, p. 351-355) find for Geissler tube helium X,= 

 5875.812 and A2=5876.i47. The distances between the compo- 

 nents deduced from these two sets are .323 and .335 respectively. 

 On the other hand, Hale and Ellerman (Astrophys. Journ. 2, p. 165.) 

 and Mohler and Jewell (1. c.) find for solar helium distances of 

 .357 and .341 respectively. 



The foregoing results having all been obtained by means of 

 gratings it seemed to the writers desirable to make an independent 

 determination by means of the Interferometer. 



For the helium Geissler tubes used in this work the writers are 

 indebted to Dr. E. C. Franklin of this University who kindly placed 

 at their disposal a number of tubes which he made in 1895. One 

 of these was so far superior in brilliancy to the rest that it was 

 used exclusively in the work. The helium was made from Samar- 

 skite and seemed to be remarkably pure, the tube showing only 

 the following lines, all of which belong to helium. 



6678 



5876 



5048.4 



5016 



4922.2 



4713-35 



447175 

 The tube was placed in series with an adjustable resistance of 

 amyl alcohol, in the secondary of a large induction coil, the pri- 

 mary of which was connected through an adjustable resistance to 



(85) KAN. UNIV. QUAU., VOL. VHI. NO. 3, APR., 1899, SERIES A. 



