CH. I] MAGIC LANTERN WITH DIRECT CURRENT 



3 1 



It should be a part of regular routine to look in the slide carrier 

 at the close of'everv exhibition to make sure that the last lantern 



tr- ^ ^ 



slide has-been removed. 



FIG. 14. SHIELD FOR THE OBJECTIVE IN INTER- 

 MITTENT PROJECTION WITH SLOW- 

 LIGHTING RADIANTS. 



S l Shield raised to allow the light to pass from the objective to the screen. 



S Shield down in front of the objective to cut off the light from the screen. 



The shield should be of a concave form and in front of the objective a short 

 distance to avoid heating. It should be made of metal or asbestos and be 

 hinged so that it can be easily turned up or down. 



This is also the best time to arrange the slides in the box or a 

 pile exactly as they were at the beginning of the exhibition ; then 

 the set will be ready for use at the next lecture or demonstration. 



41. Lantern slides permanently fixed in individual carriers. 



Originally lantern slides were mounted in wooden frames. Each 

 slide then had its own carrier, which was inserted in a special 

 opening for it next the condenser (fig. 15, 32). This method of 

 mounting slides still prevails for some purposes. If one wishes to 

 use them in the ordinary lantern the common slide-carrier (fig. 6) 

 is removed entirely ; then each slide in its carrier is inserted in 

 order during the exhibition. This method of mounting is 

 admirable for a small collection of slides, as the wooden frame pro- 

 tects them, but for a large collection they take too much space and 

 arc too expensive. 



