152 



DRAW INC WITH THE MICROSCOPE 



[ CI I. V 



If the micrometer scale is added to every drawing, there is no 

 need of troubling one's self about the exact distance at which the 

 drawing is made, convenience may settle that, as the special mag- 

 nification in each case may be determined from the scale accompany- 

 ing the picture. It should be remembered, however, that the con- 

 ditions when the scale is drawn must be exactly as when the draw- 

 ing was made. 



Fig. 132 A. B. Abbe Camera Litcida. (A.) In I his figure the camera 

 lucida is in position for drawing. The ring or collar supporting the mirror 

 is graduated so that the angle of Hie mirror may be exactly determined. 

 Smoked glasses serve to modify the light from the microscope or from the 

 drawing surface as needed. By means of a clamping ring the instrument may 

 be raised or lowered to accommodate the eye-point, in different oculars. 



(II.) In this figure the camera lucida prism is turned back so that one 

 may took directly into the ocular. (Cuts loaned by the liauseh & Lomb Opti- 

 cal Co.) 



§ 208. Drawing at Slight Magnification. — .Some objects are 

 of considerable size and for drawings should be enlarged but a few 

 diameters, — 5 to 20. By using sufficiently low objectives and differ- 

 ent oculars a great range may be ■ obtained. Frequently, however, 



