70 



thing be omitted. Drawings thus made form a valu- 

 able record, not only for the individual, but for others 

 who are following the same line of study. 



Camera Lucida How to Use it. The camera 

 lucida is the apparatus by means of which drawings 

 are made. There are various forms of these. The 

 methods of attaching to the tubes are also numerous, 

 but a very simple and effective device is that shown 



Fig. 19- 



in Fig. 19. The mounting is fixed to the cap of the 

 eye-piece by means of a flexible grooved ring. 



In this form the pencil point is not plainly visible, 

 and a number of other forms are in use which are 



