The Interference of Natural Light on a Magnetic Field 5 

 TABLE III— For a Rotation of 450° 



TABLE IV— For a Rotation of 630° 



In consideration of the fact that the observations of Sohncke 

 were made for a rotation of only 9.2 ° in each coil, it seemed 

 worth while to make use of the apparatus mentioned above to 

 carry out that investigation for some 720 . In the work of 

 Sohncke, however, a type of interference system was used which 

 involved no reflecting surfaces. At first glance it would seem 

 that' the results obtained from the present form of the experiment 

 were vitiated by the use of plates giving reflections. It is true 

 that a portion of the light passing through the coils will be po- 



149 



