64 



DO AND DO NOT WITH THE MAGIC LANTERN [Cn. I 



99i. Summary of Chapter I : 



Do 



1 . Connect both supply wires 

 to the arc lamp as indicated in 

 fig. 3, i. e., connect the positive 

 wire with the binding post of 

 the upper carbon and the nega- 

 tive wire with the binding post 

 of the lower carbon. 



Make sure of the polarity 

 ( 80). 



2. Always use a rheostat or 

 other balancing device with an 

 arc lamp (6). 



3. Insert the rheostat along 

 one wire (fig. 1-4). 



4. Insert the ammeter along 

 one wire (fig. 2,4). 



5. Always have a double-pole 

 switch on the lantern table (fig. 

 i-3). 



6. Insert the switch along 

 both wires, and before the 

 rheostat, so that all the appara- 

 tus on the lantern table has no 

 current when the switch is open 



(fig. 3). 



7. Always open the switch 

 before changing any of the 

 wires. 



Do NOT 



i. Do not connect the nega- 

 tive wire to the upper carbon 

 and thus make the polarity 

 wrong. 



2. Never try to use an arc 

 lamp without a balancing device 

 (rheostat, etc.). 



3 . Do not connect both wires 

 with the binding posts of the 

 rheostat, but insert it in one 

 wire. 



4. Do not connect the am- 

 meter with both wires. Insert 

 it in one wire. 



5. Do not try to get along 

 without a double-pole table 

 switch. 



6. Do not insert the switch 

 along one wire, but connect it 

 with both wires. Do not put 

 the switch after the rheostat, 

 etc., but before. 



7 . Never change wires on the 

 apparatus until the current is 

 turned off by opening the 

 switch. 



