CHAPTER V 



DRAWING WITH THE MICROSCOPE 



APPARATUS AND MATERIAL FOR THIS CHAPTER 



Microscope, Abbe and Wollaston's camera lucidas, drawing board, thumb 

 tacks, pencils, paper, and microscope screen, (Fig. 59), microscopic preparations. 



DRAWING MICROSCOPIC OBJECTS 



§ 177. Microscopic objects may be drawn free-hand directly from 

 the microscope, but in this way a picture giving only the general ap- 

 pearance and relations of parts is obtained. For pictures which shall 

 have all the parts of the object in true proportions and relations, it is 

 necessary to obtain an exact outline of the image of the object, and to 

 locate in this outline all the principal details of structure. It is then 

 possible to complete the picture free-hand from the appearance of the 

 object under the microscope. The appliance used in obtaining out- 

 lines, etc., of the microscope image is known as a camera lucida. 



§ 178. Camera Lucida. — -This is an optical apparatus for en- 

 abling one to see objects in greatly different situations, as if in one 

 field of vision, and with the same eye. In other words it is an optical 

 device for superimposing or combining two fields of view in one eye. 



As applied to the microscope, it causes the magnified virtual im- 

 age of the object under the microscope to appear as if projected upon 

 the table or drawing board, where it is visible with the drawing paper, 

 pencil, dividers, etc., by the same eye, and in the same field of vision. 

 The microscopic image appears like a picture on the drawing paper 

 (see note to § 181). This is accomplished in two distinct ways : 



(A) By a camera lucida reflecting the rays from the microscope so 

 that their direction when they reach the eye coincides with that of the 

 rays from the drawing paper, pencil, etc. In some of the camera 

 lucidas from this group (Wollaston's, Fig. 112), the rays are reflected 

 twice, and the image appears as when looking directly into the micro- 

 scope. In others the rays are reflected but once, and the image has 

 the inversion produced by a plane mirror. For drawing purposes this 



