CH. X] DRAWING WITH CAMERA AND MICROSCOPE 333 



it some tracing paper. By covering the head with a focusing cloth 

 to shut out the surrounding light, one can trace the outlines of the 

 object on the tracing paper, and transfer these to ordinary drawing 

 paper, and proceed to ink them in and give the shading necessary 

 free-hand. 



With the magic lantern or with the opaque lantern the image is 

 projected upon the drawing surface and regular drawing paper can 

 be used to make the original pencil tracing upon, but with the 

 camera one must use translucent paper for the tracing and then 

 transfer it to the drawing paper. (To get an erect image with 

 translucent paper see 519). 



DRAWING WITH THE PROJECTION MICROSCOPE 



472. Range of objects. For drawing as for projection it is 

 exceedingly desirable that the projection microscope should enable 

 the investigator to commence where the magic lantern leaves off, 

 and to carry the \vork to its utmost possibilities; that is, begin- 

 ning with large specimens of 50 to 60 mm. (2 in.) in diameter re- 

 quiring low objectives, and going on from this to the smallest 

 objects visible and using the oil immersion objective at the other 

 extreme. 



To realize this ideal possibility one must have available for 

 drawing some such outfit as that described in Ch. IX for projec- 

 tion ; and in addition suitable arrangements for reflecting the image 

 down upon a horizontal drawing surface. Fortunately, the addi- 

 tions are relatively simple and inexpensive. 



Finally, for the widest usefulness in drawing there must be the 

 possibility of using the ordinary house electric lighting system for 

 an electric lamp with small carbons (see 486). 



473. Drawing large objects with low powers. For this it is 

 necessary to have a stage with a large opening (fig. 134), and the 

 objective must be mounted in a shield with no tube at all (fig. 138), 

 or the tube must be short and of large diameter, so that the field is 

 not restricted (fig. 137). Finally, there must be some means of 

 increasing or diminishing the distance between the objective and 

 the drawing surface to get the desired magnification. 



