32 



The Microscope 



Figs. 36, 37, 38, and 39. Substages. Figs. 36 and 37 illustrate the Abbe-type 

 substage on a Bausch and Lomb model DDE. Fig. 36 shows the condenser being 

 inserted on a dovetail slide. In Fig. 37 the substage iris has been swung out to show 

 the rack-and-pinion lateral motion. In both Figs. 36 and 37 the supplementary con- 

 denser lens used with low powers has been swung out to the left. Figs. 38 and 39 

 show the fork type of substage mount on an American Optical Company model No. 5 

 microscope. In Fig. 38 the fingers are working the substage centering screws. The 

 larger screws just above the hands are the stage centering focus. In Fig. 37 the sup- 

 plementary condenser for use with low powers is being inserted in the dovetail slide. 

 Notice the substage fine-adjustment control just below the left-hand condenser center- 

 ing screw. 



Fig. 37 to show the rack-and-pinion that controls lateral motion. This 

 rack-and-pinion is provided with a click stop to indicate the centered 

 position, and the utmost care must be taken that the iris is clicked home 

 before the substage is centered. The supplementary lens, also mounted 

 on a swing-out arm, is shown out in both pictures. 



Figures 38 and 39 show the fork-type substage mount favored by the 

 American Optical Company. The iris diaphragm is built into the condenser 



