I/O THE HISTORY AND DEVELOPMENT OF THE MICROSCOPE 



rather supplants the usual milled head ordinarily placed at the top of 

 H ( fig. 128). One consequence of this is that the speed of the fine 

 adjustment is slowed down so much that while Zeiss stands of the 



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FIG. 132. Watson's lever fine adjustment (1889J. 



usual form give only r ^ r th inch for a revolution of the milled head 

 of the ordinary micrometer head, this form of fine adjustment gives 

 eis-th inch for a revolution of the small milled heads W W (figs. 128, 



