198 



THE PROJECTION MICROSCOPE 



[Ch. VI 



With small classes (10 or 15) where the screen distance can be 

 reduced to about one meter demonstrations with oil immersion 

 objectives are satisfactory. However, when the finest details of 



*<s 



.--•* 



= 9 ..-- 



Fig. 119. Diagram of Adams' Solar Microscope. This Illustrates Well 

 the Advantage of Some Form of Projection Microscope for Demonstra- 

 tion Purposes. 



structure are to be seen most successfully under high powers, each 

 individual must look into a microscope for himself and attend to all 

 the finer adjustment and lighting. 



Conduct of a Demonstration with the Projection 



Microscope 



§ 312. Preparedness. — From the great difficulty in making 

 really good projection demonstrations with the microscope the prepa- 

 ration should be thorough. The following are some of the most 

 important things to look after: 



(1) If any of the objectives used are of the photographic type 

 and have an iris diaphragm, that should be opened to the fullest 

 possible extent. 



(2) The microscopic slides to be used should be in order so that 

 they can be easily grasped. 



