132 



THE MICROSCOPE. 



The Camera Lucida. 



The main point to be observed when using the 

 Camera Lucida is that the microscope shall be placed 

 in the horizontal position, and the object well lighted. 

 The Ross-Wollaston Neutral Tint Camera Lucida con- 

 sists of a metallic cylinder, cut at an angle of 45 to its 

 axis, thus producing an elliptical opening, into which 



FIG. 78. The Ross-JFollaston Camera Lucida. 



a plate of neutral tint glass is fitted. Opposite to this 

 is an opening about half an inch in diameter, through 

 which the student may view, and trace or measure the 

 object on drawing-paper, the microscope with the 

 camera attached to the eye-piece having been previously 

 brought into a horizontal position. 



