738 



SUMMARY OF CUKRENT RESEARCHES RELATING TO 



projection lenses. The Microscope-tube T slides into the sleeve attached 

 to the lens-holder. When the distance of the fine-adjustment micrometer 

 screw exceeds a convenient limit, as in fig. 124, the focusing gear supplied 



S 



a 



9^ 



mf 



a 



% H,' Ji^i 



Kt 



Fig. 122. 



with the apparatus should be attached. The hand-regulated lamp 

 requires a 4-ampere current, and has its carbons inclined at 90° to each 

 other, the positive carbon being held in the direction of the optic axis. 



