PHOTOGRAPHIC PROCESSES. 



119 



Fig. 28. 



The microscope lamp or Swan's electric light, the 

 former being preferred with the power, we are about 

 to use, is got ready and placed on the stand. The 

 microscope with eye- piece attached being fixed in 

 position, the centering is carried out by a low power 

 objective as before described. All these manipula- 

 tions are performed by the hands through the 

 sleeves, or better through the windows in the same 

 position. These windows should of course be cap- 

 able of subsequent closure by sliding doors. The 



