272 THE BOOK OF THE LANTERN. 



half a minute before the change of picture is really 

 required, 59 as to give the operator time for the necessary 

 manipulation. He should be instructed when to dissolve 

 the view slowly, should he be using a double or triple lan- 

 tern, and when to make the change quickly. To dissolve a 

 diagram or a portrait is ridiculous, and sometimes leads to 



FIG. 75. 



4 



very comical effects. I remember once attending a lecture 

 where a number of illustrations were shown of different 

 types of national costumes. First of all there came a 

 woman in peasant's dress. This was followed by a man 

 whose lower extremities were clothed in tight-fitting white 

 unmentionables. It so happened that one figure occupied 

 on the screen exactly the same place as the other, so 



