ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



747 



The Comparascope consists of a mount into which a second object- 

 glass 2 can be screwed at right angles to the body tube. A strong but 

 very light dovetailed bar D projects about 3 in. from the Microscope 

 tube, and carries upon it a movable stage S, upon which an ordinary 

 3 in. by 1 in. slide is held by spring clips. At the far end of the dove- 

 tailed bar slides a mirror M in gimbals, and in the centre of the com- 

 parascope mount is a right angle prism P, which reflects the light from 

 the object-glass 2 into one half, while the light from object-glass 1 

 proceeds directly to the other half of the field of the Microscope. 



I' 16. 167 — View from Above. 



Fie. 1G8.— Side View. 



Fitting into the Comparascope mount is a thin septum E, which projects 

 sufficiently far into the body tube to prevent the light from one side of 

 the field reaching the other half. The prism P can be slipped out of 

 position by means of the milled head L at any time, thus throwing the 

 Comparascope out of use. The stage S which slides along the dovetail 

 D, may be clamped in any position by the screw K upon the rod R, and a 

 fine adjustment for focusing high powers is then available by revolving 

 the milled head F. In order that the instrument may be equally 

 serviceable for high powers, a small substage carrying a condenser C. 



