Part IT1.—Magnetic Perturbations of the Spectral Lines. 21 
ADDENDUM. 
Since the foregoing was written I have examined several spectral lines in a 
magnetic field of which the strength could be gradually increased up to a value 
considerably exceeding 40,000 C. G. S. units. In this very intense field I had 
hopes that some further resolution of the spectral lines might be observed, and in 
this hope I have not been disappointed. For example, the quartet form, such as 
the lines 5172°8 Mg, 4800 Cd, and 4722 Zn, becomes distinctly resolved into 
a sextet, the resolution taking place by the splitting up of each of the side lines 
into a doublet. This is shown in figs. 10 and 11, of which fig. 10 shows the 
Fic. 10. Fie. 11. 
magnetic effect as presented to the eye by a field of, say, 20,000 C. G.S. 
units, whereas fig. 11 shows the further resolution produced by a field of 
strength approaching 40,000 units. It thus appears that the quartet form as 
heretofore noticed is really a sextet in which the separation of the com- 
ponents of the side lines is considerably less than that of the components of 
the middle line. 
Even in this intense field the normal, or pure, triplets of the type 5167°5 Mg, &c., 
remain firm, and do not split up further, or, at least, the evidence of further 
splitting up is too slight to enable one to state that any positive indication in that 
direction exists. 
In the case of the complex, or diffuse, triplets of the type 5183°8 Mg, 
5086 Cd, 4810-7 Zn the character of the resolution become quite cleared up. 
For what was in the weaker fields merely a diffuse or nebulous triplet is now 
shown to be a triplet in which each constituent consists of three fine lines. These 
les are not of the sharp, steady character possessed by those of the normal 
triplet, but are of an unsteady, flickering character, and are backed by a 
good deal of hazy nebulous light. Further, the component nine lines are not 
equally bright, except in the case of the central three, which are fine and equally 
spaced. The triplets which form the wings, however, have their outer components 
