220 PHOTOGRAPHING WITH THE MICROSCOPE [Ch. VH 



For convenience and rapidity of work a microscope with mechani- 

 cal stage is necessary; and for sections where it is desirable to have 

 the image in some regular position a revolving stage to the micro- 

 scope helps greatly in orienting the image on the plate. 



It is also an advantage to have a tube of large diameter so that the 

 field will not be too greatly restricted (fig. iii). In some microscopes 

 the tube is removable almost to the nose-piece to avoid interfering 



Fig. 131. Horizontal Projection Microscope for Drawing and foe 

 Photo-micrography. 



(About t'u natural size. From Optic Projection). 



The wiring is for an arc lamp with right-angled carbons. The condenser 

 has three lenses and a water cell between the two plano-convex ones. 



P L Concave parallelizing lens to supply the substage condenser with 

 parallel beams. (See also fig. 115). 



M2 45° mirror in dotted lines beyond the ocular to reflect the image 

 down upon the surface of the table for drawing. 



with the size of the image. The substage condehser should be mov- 

 able on a rack and pinion. The microscope should have a flexible 

 pillar for work in a horizontal position. While it is desirable in all 

 cases to have the best and most convenient apparatus that is made, 

 it is not by any means necessary for the production of excellent work. 

 A simple stand with flexible pillar and good fine adjustment will 

 answer. 



§ 343. Objectives and oculars for photo-micrography. — The 

 belief is almost universal that the apochromatic objectives are most 



