710 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



pointer, or index finger, carried on angular bridge q of telescope-tube 

 to point out angle on graduated scale ; M is a black concave disc rotating 

 with the tube d ; wio are the mires, made of translucent material ; 

 12, 12 are hemispherical shells containing the light, connected with 



Fig. mo. 



wires running from insulated rings in the hollow stem t ; / is the 

 inner or sliding tube of telescope, carrying a prism h h, whose refractive 

 plane is in the plane of the mires: this tube has a rack o attached 

 thereto for moving it; this rack projects through a slot m, and is 

 engaged by a pinion p, by which the inner tube is carried back and 



