ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



599 



without altering the position of the body-tube of the Microscope, 

 thereby not disturbing the adjustment for illumination with the vertical 

 illuminator for various powers. A Hooke's key is attached to the 

 micrometer movement, so that it can be worked from behind the camera. 

 The upper portion of the Microscope carrying the wide body draw-tube 

 is also of special construction, to insure rigidity. It is provided with 



Fig. 65. 



rack-and-pinion and clamping screw, and also with an illuminating 

 device facilitating vertical illumination for very low-power work. For 

 high-power work, a vertical illuminator is supplied, consisting of a 

 totally reflecting prism specially mounted and fitted with an iris 

 diaphragm. The vertical illuminator is so arranged that it can be 

 rotated round the axis of the Microscope, and as the totally reflecting 



