ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



821 



2. Camera lucida with double reflection, Fig. 181. The first re- 

 flection is from a thick film of silver, the second is from a thinner 

 film. The thickness of the second film may be adjusted as described 

 above. It will be seen that the plane of delineation is seen through 

 the second reflector, not past it as in the ordinary instrument. (In 

 the diagrams the thick oblique lines are the silver films, the thin 

 lines the directions of the light, the arrows the objects, and the dotted 

 lines the paper on which the objects are to be drawn.) 



Fig. 181. 



Fig. 182. 



3. A form of reflecting camera for sketching microscopical objects, 

 Fig. 182. This instrument being fitted to the eye-piece of the Micro- 

 scope, the paper and pencil point under the larger reflector appear in 

 the field of the Microscope. The object is seen direct. The second 

 mirror in the instrument exhibited was an inch square. This instru- 

 ment may be used with the body of the Microscope at any angle, it 

 being merely necessary to place the drawing paper in a plane parallel 

 with that of the microscope-stage. (In the Figs. 182 and 183 the 

 mirrors are represented as parallel ; they should usually be slightly 

 inclined to each other, to increase distance between plane of 

 delineation and the object.) 



4. Another reflecting camera for sketching small objects is re- 

 presented in Fig. 183. In the instrument exhibited, the larger 

 reflector was 1^ by If inches 

 and placed 10 inches from 

 the paper; the field was 

 about 4^ inches square. 

 This instrument may be 

 used horizontal or inclined, 

 and it is well adapted for 

 drawing such objects as in- 

 sects, leaves, shells, &c. If 

 the vertical distances be- 

 tween the mirrors and the 

 object and paper respec- 

 tively be constant in instruments of this form, the relative magnitudes 

 of object and drawing will obviously vary with the distance between 



Fig. 183. 



