DR. A. E. H. TUTTON : 

 4 



sliders which carry the two microscopes, have been provided with a slow motion of 

 this description which enables either microscope to be traversed so absolutely steadily 

 that the interference bands, generated between a vertical black-glass surface carried 



Fig. 3. Right end-elevation. 



by the microscope and the second colourless-glass surface carried in rigid attachment 

 to the bed on which the slider moves, move with perfectly steady precision, without 

 either rotation or alteration of the width of the bands, and without even the slightest 

 tremor, simultaneously with the movement of the microscope, of which they afford a 



