i68 



DRAWING WITH A CAMERA LUCIDA 



[CH. VI 



the microscope. The mirror must have its edges in planes parallel 

 with the edges of the drawing board also (fig. 102). 



275. Drawing with the Abbe camera lucida. (i) The light 

 from the microscope and from the drawing surface should be of 

 nearly equal intensity, so that the image and the drawing pencil can 



FIG. 102. BERNHARD'S DRAWING BOARD FOR THE ABBE CAMERA LUCIDA. 

 (From the Catalogue of Zeiss). 



This drawing board can be elevated and tipped; it can also be inclined, carrying 

 the microscope with it. 



be seen with about equal distinctness. This may be accomplished 

 with very low powers (16 mm. and lower objectives) by covering the 

 mirror of the microscope with white paper when transparent objects 

 are to be drawn. For high powers it is best to use a substage con- 

 denser. Often the light may be balanced by using a larger or smaller 

 opening in the diaphragm. One can tell which field is excessively 

 illuminated, for it is the one in which objects are most distinctly seen. 



