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SUMMARY OF CURRENT RESEARCHES RELATING TO 



of the box is also provided with a metal fitting into which the 

 standard carrying the Microscope can be screwed, which we regard 

 as the most convenient way of using the instrument. An extra 

 screw-arm (shown lying in front of the box in Fig. 41) is also pro- 

 vided, which can be screwed to the end of a laboratory table, as shown 

 in Fig. 40. The metal disk forming the foot in Fig. 39 also serves 

 as an ordinary self-centering turntable, as shown in Fig, 41. 



Fig. 40. 



The coarse adjustment is effected by a sliding cylindrical rod 

 attached to the buck of the microscope-body. The fine adjustment 

 consists of a large milled head attached to the lower end of the bar 

 in which the coarse adjustment rod slides, the inner face having a 

 deep spiral groove of nearly three turns, in which works a i)in jiro- 

 jecting behind the cylindrical tube carrying the stage ; the rotation 

 of the spiral causes the pin and tube, together with the stage, to move 

 somewhat slowly in a vertical direction within a range of half an inch 

 — sufficiently well for the use of low powers. (Fig. 39 shows the pin 

 in the second ring of the spiral.) 



The mirror has the usual gimbal motions, and is attached to a 



