These cameras are usually made about 8 inches broad by 6 high, 

 and will carry a 4 by 3-in. plate. The lenses of a very superior 

 quality are of If inch in diameter, and of 5 to 6 inches focus. 

 Double combination lenses may be added if desired. 



THE DOUBLE CAMERA FRONT, (Fig 5,) 



Contains the two lenses just alluded to, which 

 are moved by a rack-work adjustment (C), 

 and give a much sharper and brighter image 

 than can be obtained by the single lens. A 

 small reflecting mirror (E) is placed in front, 

 which reverses the objects in the camera, and 

 pourtrays them exactly as they appear in 

 nature. This combination is far more rapid 

 in its operation than the single lens. 



MERCURY Box. 



Fig. 5. 



This is a small box (Fig. 6) supported on two sliding legs, for 

 the sake of portability, having in the bottom an iron cup for hold- 

 ing the^mercury, and in the inside a ledge to support the frame. 



