26 MICROSCOPE, ETC 



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eye-piece and objectives. When attached to the tube 

 itself it is impossible to adopt any arrangement for 

 shortening the tube, the consequence of this is that 

 the surface of the ground glass in the camera, 

 covered by the image, is greatly contracted owing to 

 the length of tube between the objective and mouth 

 of the bellows. 



The fine adjustment should also be separate from 

 the eye-piece tube to allow of attachments necessary 

 for working it from a distance. It should respond 

 immediately to the slightest rotation in either direc- 

 tion, and the object should suffer no apparent shake 

 or displacement, when moving in or out of focus. 



Nothing belonging to the microscope is susceptible 

 of more improvement than the fine adjustment, and 

 anything which would supersede the present very 

 inferior methods by which this is effected, would be 

 welcomed by microscopists. 



The eye-piece tube must be removable from the 

 body, or better from another tube about an inch long 

 attached to the arm carrying the objectives. The 

 way this is accomplished is of no importance as long 

 as it is possible. 



The stage should be firm, and as thin as is compa- 

 tible with the use of the sub-stage apparatus, to be 

 described. Circular in form and possessing some 

 arrangement by which movements in a rectangular, 

 circular and horizontal direction may be smoothly 

 and easily communicated to the object, by aid of 

 the finger alone without the use of milled heads or 

 other mechanical arrangements. 



