On the Evolution of the Fine Adjustment. By E. M. Nelson. 375 
Herr Reichert’s patented improvement consists of adapting, in a 
most ingenious manner, a lever of the second order to the usual direct- 
acting screw. 
Hot having seen the instrument itself, I am unable to give the 
amount by which the movement is slowed down ; the drawing shows 
a ratio of 1:2^ in the arms of the lever ; therefore, if the screw is of 
the usual form, the fine adjustment will have a movement of 1/210 
in. for one revolution of the milled head, instead of 1/85 in. as at 
present. 
Figs. 95 and 96 illustrate the mechanism so clearly that no 
•explanation is required. 
There can be little doubt that this improvement will speedily 
revolutionise the form of the fine adjustments of Continental Micro- 
scopes; for it is evident to all that 1/100 in. for one revolution is 
too rapid a fine adjustment for any Microscope when critically used. 
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