i 
i} 
DUNSTAN, RICE, KRAUS: SPECTRAL LINES OF SODIUM. 85 
Exponential curves b’, c’, d’, e’, of the same form are also drawn 
through the points of half initial visibility of the curves b, c, d, e, 
Fig. 2. 
It is evident from these curves that the visibility curve has 
changed form, and hence the distribution of light in the source has 
been somewhat modified by the influence of the magnetic fields; 
but still the visibility curves for maxima are non-periodic, and 
fair approximation to the form and breadth of the source may be 
obtained from these exponential curves b’, c, d’, e’, whose equa- 
tions are: 
cc 
Ounveray. Vea 70x 2 
GurVerbl Wire 70 ci 
(is) 
CG ) 
( 
) 
D 
Grae reas | Wie 76 eZ 
G@urveree Vv 76 62 (<3 
It may be noted in passing that the period of the complete visi- 
bility curve is not changed by the influence of the magnetic field, 
so that the mean distance between the two sodium lines is not 
thereby altered, but only the distribution of light in each line. 
Also, that very considerable changes in the bunsen flame itself 
make no difference in the visibility curves of the sodium lines, and 
hence the effects observed cannot be explained on the eround of 
Variations in the brilliancy or intensity of the flame. 
From the equations of the curves a’, b’, c’, d’, e’, Fig. 2, are cal 
culated the half widths of one of the sodium lines under the influ- 
‘nce of various magnetic fields. 
Che values are: 
.0425 Angstrom units 
8, 5. 
dy 0549 ve f 
Ogs=, 0038 te ne 
8, .0750 66 66 
0, == 1320 a oy 
and the curves (x) for the assumed exponential law of distribution 
of intensities in the source are plotted in Fig. 3 as curves a, bey 
d, e, whose equations are: 
