270 EXHIBITION WITH PROJECTION MICROSCOPE [Cn. IX 



CONDUCT OF AN EXHIBITION OR DEMONSTRATION WITH THE 

 PROJECTION MICROSCOPE 



400. What is said in Ch. I, 21-40 is entirely applicable to 

 the projection microscope by substituting microscopic specimens 

 for the lantern slides. Only from the greater difficulty and pre- 

 cision demanded in using the projection microscope, it is impera- 

 tive that the operator be prepared, hence the greater necessity of 

 making certain that everything is in absolute order before the 

 lecture begins. 



If any of the projection objectives (i. e., those of 125 to 20 mm. 

 focus) have iris diaphragms, open these as widely as possible. 

 Never try to project with the iris of the objective partly closed. 



FIG. 148. SI.IDH-TKAV WITH MASKKD PREPARATIONS TO HE USED IN 

 PROJECTION. (About Y* size). 



Three series are here represented on different sized slides. 



The seetions to be shown are not eovered with the masking paper. The 

 numeral on the side give the number of the series (ser. 90, ser. 17, ser. 15). On 

 eaeh slide is also the number of the slide in the series as ser. 15, slide 57, 63, 67, 

 etc. 



