308 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



The Microscope consists of two tubes only, tlie objective being 

 screwed to the outer one and the eye-piece sliding in the inner. 

 A pin on the inner tube works in a slot in the outer, serving as a 

 guide when the former is drawn out. "With the eye-piece tube closed, 

 the instrument is 4 J in. long and extended 6| in. The power varies 

 from 3 (closed) to 12 (extended), with a working distance of from 

 6i in. to 3 in. The adjustment for focus is of course made by moving 

 the whole Microscope to and from the object. 



Winkel's Demonstration Microscope. — The speciality of this 

 instrument (fig. 5G) consists in tlie arrangement for moving the object. 

 This is effected as represented in fig. 57, which shows the lower part 



of the Microscope when the upper 

 Fii;. r)0. portion is disconnected. The slide 



is attached by spring clips to the 

 movable plate, shown in the fig., 

 which has a long slot working on 

 a pin, so that the plate can be 

 moved laterally for rather more 



Fig. 57. 



than 1/2 in. At the same time a 

 motion in arc for about the 

 same distance can be obtained by 

 pivoting the plate on the pin. The 

 combination of these two motions 

 brings all parts of the object into 

 view. Since fig. 56 was drawn, 

 three feet have been added, forming a tripod support for the instru- 

 ment when standing on the table. The fine adjustment screw has 

 also been removed from its position at the top of the base and placed 

 below. Its action is to raise or lower the slide-plate at one end 

 slightly. Tliere is a spring clip on the top of the base to receive 

 a card with tlie name of the object. 



ToUes' Clinical Microscope. — This (fig. 58) consists of a prin- 

 cipal tube or sheath, into the upper end of which slides the body-tube, 

 with eye-piece and objective, while in the lower end works a third 



