782 Mr. F. Twyinan on an Interferometer 



is provided so that the angle through which the axis of the 

 lens is turned can be measured. Upon the bar and at right 

 angles to it is mounted a crossbar, 160 (fig. 8), whose distance 



Fisr. 7. 



Fig-. 10. Ji 



228 -^ 



P LAN 



114 228 118' 



from the axis of rotation of the lens can be adjusted and 

 measured by a scale engraved on the axial bar 105. The 

 convex mirror 001 (fig. 6) bj which the light is reflected 



