QO MAGIC LANTERNS WITH MAZDA LAMPS [Cn. Ill 



assumed that if he had possessed the technical knowledge no mis- 

 takes, and hence no accident would have happened. 



135. Use of the small arc lamp for demonstrations and 

 exhibitions. The centering of the apparatus to one axis, and 

 using the correctly proportioned condenser and projection objec- 

 tive, the lighting and putting out the lamp, arrangement and 

 insertion of lantern slides, etc., are all exactly as described in Ch. 

 I, II ( 26-41, 52, 112). 



FIG. 51. MAGIC LANTERN WITH SMALL ARC LAMP. 

 (Balopticon B.; Cut loaned by the Bausch & Lomb Optical Co.). 



MAGIC LANTERN WITH A MAZDA, CONCENTRATED FILAMENT 

 INCANDESCENT LAMP 



136. Next to the arc lamp the Mazda concentrated filament 

 lamp is perhaps the best electric light at present available. They 

 arc as simple to use as an ordinary incandescent bulb. No rheo- 

 stat is necessary. The lamp is on a stand by which it may be 

 raised and lowered and brought the proper distance from the con- 

 denser (fig. 52-53). 



137. Connections with the house circuit. This is made by a 

 double flexible cable, one end of which is connected with a separable 

 plug, and the other with the lam]) socket of the Mazda lamp. As 

 no rheostat is used, and as the light is turned on and off exactly as 

 for any incandescent bulb, this light is absolutely simple in use. 

 It gives a light sufficient for a small room, where not over 50 to 

 IDC people are to watch the exhibition. 



