microscope which would form an elongated or distorted 

 image and to correct this the drawing surface must be 

 sufficiently tilted to bring it at right angles to the axial 

 ray. An easy method to determine whether the surface 

 is at a right angle is to mark the outlines of the field of 

 view on the paper at the right and left and at the front 

 and back extremes and measure the distance. The 

 surface should be so tilted that the distance in both 

 directions is the same. 



If the microscope is tilted another complication 

 arises inasmuch as the drawing surface must be tilted 

 with it. 



Field and Magnification. The size of the 

 drawing of an object depends upon 



the initial magnification of the microscope, 

 the distance of the drawing from the eyepiece. 



Drawings should be made with such objectives and 

 eyepieces as would be used to examine structure. As 

 the distance of the drawifig surface from the eyepiece 

 is increased the image becomes larger. The size of 

 drawing must therefore be regulated by varying the 

 height of the drawing surface. 



To Use the Simple Camera Lucida. Focus 

 the objective upon the object ; incline microscope to the 

 horizontal position, raise microscope by underlaying with 

 blocks or books, readjust mirror and attach camera 



172 



