82 Proceedings of the Royal Society of Edinburgh. [Sess. 
change in dissymmetry. The distances are here given from the unseparated 
spectral line, and these measurements have been transformed to angstroms 
to show the alteration in wave-length produced. The field strength was 
slightly smaller than before, being 22,000 gauss. It will be seen on compar- 
ing this with Table I., that the amounts of dissymmetry have changed, and 
that some cases of normal dissymmetry have even become abnormal, owing 
to the new arrangement of the apparatus. The motions of the centre com- 
ponents and of the mean of the outer components from the original position 
of the spectral line are in some cases quite appreciable, and beyond the 
range of the errors of measurement. 
A further experiment was made, in which the light, in addition to passing 
through the quartz lens, was made to penetrate a quartz plate, 5 mm. thick. 
The distances of the outer components from the middle component are 
given. In this case the field strength was a little higher, being now equal 
to 25,700 gauss. 
Table IV. — Light through Quartz Plate, 5 mm. thick. 
Field strength = 25, 700 gauss. 
Remarks. 
Min. intensity 
of mid. compt. 
A = 2630 approx. 
Max. intensity 
of mid. compt. 
A = 2750 approx. 
Min. intensity 
of mid. compt. 
A = 2960 approx. 
Wave- 
length. 
• m 
t3 tj 
a 
in 
in 
3025-01 
3041-96 
3049-80 
3311-53 
3361-25 
n 
a 
n 
n 
n 
oS r< 
£ £ 
«-8 b . 
p 
C5 1 , r O 
+ 03 
§ . -P5 
!=; -+-3 
g o 
.2 or 
QO^ 
I 
-0-157 
0 
+ 0-146 
-0 141 
0 
+ 0-130 
Intensity. 
Remarks. 
4 1 
3 J- 
4j 
3 l 
4 r 
3 J 
4 1 
Components 
4 r 
broadened and 
1 1 
difficult to 
4 J 
measure. 
4 1 
8 r 
4 J 
2 4 
3 r 
2 J 
As there is now a much greater thickness of quartz, the amount of 
rotation is much increased, and hence the cycle of changes in the intensities 
is passed through very much more quickly. From observing all the lines 
