702 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



optical axes of the achromatic lenses is approximately equal to the 

 angle between rays diverging to the eyes from a point at the distance 



Fig. 152. 



Fig. 154. 



of normal distinct vision. The screw S S' allows the emergent rays to 

 be accommodated to the distance between the observer's pupils. This 



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