THE BOOK OF THE LANTERN. 



is the attachment shown at fig. 61. This contrivance 

 may be compared to an ordinary microscope with its tube 

 removed, and with the lantern light at the back of the 



FIG. 61. 



stage instead of the mirror. The attachment is fixed 

 on the lantern in place of the usual objective, and the 

 objects to be shown are supported in a vertical position by 

 spring clips. The microscope objective is held, as shown, 

 on a movable arm worked to and fro by a milled headed 

 focussing screw. At the back of the object is a substage 

 condenser, not shown in the cut, and a revolving plate 

 with different sized diaphragms. A trough containing a 

 saturated solution of alum is placed on the lantern stage 

 to protect the objectives from heat. In using the instru- 

 ment the limelight must be adjusted in distance from the 

 condensing lens for each different power used; and, indeed, 

 for every change in the diameter of the diaphragm 

 employed. For living objects, such as those illustrating 

 pond life, a small tank is used, and is placed against 

 the spring clips. The objectives suitable for this form 

 of instrument are those which range between 3 in. 



