140 
Transactions of the Society. 
is situated comparatively near to the body-tube, the motion of the 
micrometer screw being thus reduced. The coarse adjustment is 
effected by raising and lowering the fulcrum of the fine adjustment 
lever. This is done by a second lever F, whose fulcrum G- lies 
beyond that end of the fine adjustment lever furthest removed from 
Fig. 28. 
the body-tube. This coarse adjustment lever is controlled by a screw 
H working into a nut J placed one-third of the lever’s length from 
its fulcrum. In this way the motion of the coarse adjustment screw 
is imparted in an increased form to the fine adjustment lever. Since 
then the motions of both coarse and fine adjustment screws are 
imparted ultimately to the end C of the fine adjustment lever which 
