CHAPTER III. 



MAGIC LANTERN TO BE USED ON THE HOUSE 

 ELECTRIC LIGHTING SYSTEM 



120. Apparatus and Material for Chapter III : 



Suitable room and screen (Ch. XII) ; Magic lantern with lamp- 

 house and lantern table; Arc lamp for small carbons ( 127); 

 Rheostat ( 129); Flexible cable for connecting the lamp and 

 rheostat with the house lighting system (fig. 40) ; Separable plugs 

 and extension plugs (fig. 49-50); Polarized plugs (fig. 48-49); 

 Nernst lamps (fig. 54-55); Objective shield (fig. 14); Concen- 

 trated filament, Mazda lamps ( 136) ; Flash-light; testing lamp, 

 screw drivers and pliers; lantern slides, etc., as in Ch. I. 



121. For the historical summary of the use of the house, 

 electric lighting system for the magic lantern, see the Appendix. 



For works of reference see 2. Consult also the Microscopical 

 Journals, and the catalogues of manufacturers of projection 

 apparatus. 



MAGIC LANTERN WITH SMALL CURRENT ELECTRIC LIGHTS FOR 

 LABORATORY AND HOME USE 



122. For public exhibitions and large lecture rooms special 

 electric wiring and large current arc lamps are necessary, as 

 described in Ch. I, II and XIII. For small audiences as in labora- 

 tories and for home use, where less than 100 people are usually 

 present, very satisfactory results may be obtained by means of 

 lighting apparatus drawing current from the ordinary house light- 

 ing system ; and the electric current may be direct or alternating. 



123. Kinds of lamps to be used with small currents. There 

 are three forms of lamps which have been successful for use with 

 the magic lantern drawing current from an ordinary lighting 

 system : 



(i) An arc lamp of small size using small carbons, i. e. carbons 

 of 6 to 8 mm. (% to r /i<; in.) in diameter. A large arc lamp 

 is equally available if it has long clamping screws, bushings or 



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