218 



THE BOOK OF THE LANTERN. 



tain an ordinary microscopic lamp, an objective whicli 

 screws into one end of the box, and a movable stage 



FIG. 54. 



to hold the object, having a screw attachment, so that 

 it can be moved to and from the objective in order 

 that the image may be sharply focnssed upon a plate 

 held in a frame outside. This frame is fixed to a 

 grooved board, which can be moved in and out of the base 

 board, and this movement determines the distance of the 

 image projected from the lens, and therefore the size of 

 that image. The apparatus may indeed be compared to 

 an optical lantern in its arrangements, except that the 

 condensing lens (an ordinary one on a stand such as is 

 used for microscopic work) is contained within the box, 

 and that the object to be projected is on a special form of 

 movable stage, as above mentioned. This stage, or fine 

 adjustment, consists of two parallel and horizontal bars, 

 with a fine screw of the same length laid between them, 

 and which works in a threaded orifice in the lower part of 

 the stage. The end of this screw nearest the light is 



