3Q8 MOVING PICTURE APPARATUS [Cn. XI 



(9) No wire of less size than No. 6 B & S gauge shall be used in 

 any projection arc circuit. 



(10) Only link fuses, enclosed in suitable metal cabinet with 

 spring door, shall be allowed in any operating room. 



(n) All wires, except asbestos covered from outlet to lamps, 

 shall be in conduits. 



(12) All switches shall be enclosed (fig. 278). 



(13) All carbon butts shall be deposited, immediately on 

 removal from lamp, in metal can containing water. 



(14) All films shall be kept in solderless metal case with ap- 

 proved spring-closing cover, or door. 



(15) Smoking shall be absolutely prohibited inside the operat- 

 ing room. 



(16) There shall be no reading matter inside any operating 

 room. Reading matter to be construed to mean newspapers, 

 novels, etc., but not including catalogues, or books of instruction, or 

 magazines helpful to the operator in his work. 



(17) Not to exceed one ounce of alcohol or one pint of lubricat- 

 ing oil shall be allowed in the operating room. Benzine, kerosene 

 and like substances shall not be kept in any quantity in any theater. 



(18) Machines may be motor driven. 



(19) All machines shall be firmly and effectively anchored to 

 the floor." 



558. Source of electric current. Next to be considered is the 

 source of current supply. If one is in a place where there is a good 

 electric system in operation it is usually much better to buy the 

 power than to try to run a special power plant. This is because of 

 the greater certainty of the city power and the absence of responsi- 

 bility. It is, however, perfectly feasible to generate power with a 

 gasoline, oil, alcohol or steam engine. When this is done the power 

 is somewhat cheaper but rather more trouble and without careful 

 attention it is less certain than a regular supply. Independent 

 generation of power in small units makes possible the direct con- 

 nection of the arc to the generator without the use of a rheostat as 

 will be explained later. (Ch. XIII, 680, see also 562). 



