57 



On a Hydrostatic Fine Adjustment. 



By E. M. Nelson. 



{Read August 28th, 1884.) 



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The growing increase in the use of wide-angled object-glasses 

 calls for some improvement in the fine adjustment of the micro- 

 scope. 



It must be remembered that depth of focus is inversely propor- 

 tional to the numerical aperture, that the microscope is now used in 

 a far more scientific manner than the rough-and-ready way of former 

 days, and that critical pictures are now the only ones accepted by 

 the best workers. A vast improvement has taken place in the con- 

 struction of object-glasses, but the arrangements for fine adjust- 

 ment remain pretty much the same as they were five-and-twenty 

 years ago. The above diagrams illustrate a method of fine adjust- 

 ment which has occurred to me, which I think would, if adopted, 

 effect an improvement in this direction. 



Fig. 1 shows in section the arrangement as adapted for a micro* 



Journ. Q. M. C, Series II., No. 10. f 



