CHAPTER V. 



DRAWING WITH THE MICROSCOPE. 



APPARATUS AND MATERIAL FOR THIS CHAPTER. 



Microscope, Abbe camera lucida, drawing board, thumb tacks, pencils, paper, 

 and microscope screen (Fig. 58). 



DRAWING MICROSCOPIC OBJECTS. 



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

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

 ance and relations of parts is obtained. For pictures which shall have 

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

 sary 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 un- 

 der the microscope. The appliance used in obtaining outlines, etc. , of 

 the microscopic image is known as a camera lucida. 



§ 169. Camera Lucida. — This is an optical apparatus for enabling 

 one to see objects in greatly different situations, as if in one field of vis- 

 ion, 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 image 

 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, pen- 

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

 The microscopic image appears like a picture on the drawing paper. 

 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, pencils, etc. In some of the camera luci- 

 das of this group (Wollaston's, Fig. 105), the rays are reflected twice, 

 and the image appears as when looking directly into the microscope. 

 In others the rays are reflected but once, and the image has the inver- 

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

 is a great objection, as it is necessary to similarly invert all the details 

 added free-hand. 



