ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



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this motion; they work one through the other, and act upon 

 racks placed at right angles. Scales placed at right angles serve 

 as finders. 



Fig. 115. 



The suhstage is similar in design to that of Messrs. Sidle, de- 

 scribed ante, p. 555, and a screw has been added to the base for 

 clamping the base-plate which rotates on the tripod. 



Guillemare's School Microscope.* — This (Fig. 116, | nat. size) 

 is the design of Professor A. Guillemare, of the Lycee Charlemagne, 

 Paris, and is apparently intended for junior pupils, its speciality 

 being the screws V and V, by which both the tube and the slide are 

 locked, so that they can only be freed by the professor with the aid of 

 the key shown in the woodcut. 



* Joum. de Microgr., vi. (1882) pp. 233-5 (1 fig.). 

 Ser. 2.— Vol. II. 2 Z 



