CH. I] " MAGIC LANTERN WITH DIRECT CURRENT 35 



slide seems to melt into the other, hence the name "dissolving 

 views." This is brought about by a shutter gradually uncovering 

 one objective and at the same time obscuring the other; or, as in 

 the figure here shown (fig. 17), by the closing of the iris diaphragm 

 of one objective while the other opens. 



FIG. 17. MULTIPLE LANTKKX FOR DISSOLVING 

 VIEWS. 



(Cut loaned by the Bausch & Lomb Optical Company). 



Each lantern must have its own arc lamp and rheostat. For dissolving one 

 picture into another the iris diaphragm of one objective is opened gradually 

 while the other is gradually closed. This is accomplished by pulling up or 

 down on the rod connecting the two iris diaphragms in the objectives. 



Some lecture rooms are supplied with double lanterns, not so 

 much for the dissolving effect, as for the rapid passage from one 

 slide to another. In most cases the "push -through" carrier with a 

 single lantern will accomplish this as effectively. 



46. Multiple lanterns for "effects." Formerly certain 

 "effects" or striking appearances were produced by the use of two 

 or more lanterns which were in operation and projected their light 



