232 



USE OF THE MICROSCOPE. 



with this instrument there is no difficulty in seeing the object 

 and pencil, but the paper must be shielded from the light. 



M. Nachet has contrived an excellent camera lucida, in 

 which the rays undergo one reflection only, and as his micro- 

 scopes do not incline, the paper on which the drawing is to be 

 made is placed on a small desk in front of the observer. The 

 camera, and mode of attaching it to the eye-piece, are repre- 

 sented by V in fig. 152,* and a section of the camera by p v, and 



of the desk c, together with the course of one ray of light, by 

 X r a. Where this camera is employed, it is not necessary 

 to keep the compound body in a vertical position; the camera 

 allowing of its being inclined at an angle of 45°, the paper can 

 be laid on the table, and the drawing made in the usual way ; 

 by this arrangement the field of view will be of much laro-er 

 dimensions than where the body is placed horizontally. 



Method of using the Camera Lucida with the Microscope. 



The first step to be taken after the object about to be drawn 

 has been properly iUuminated, adjusted,. and brought into the 

 centre of the field of view, is to place the compound body of 

 the microscope in a horizontal position, and to fix it there. 

 * Robin — Sur le Microscope. 



