76 SUMMARY FOR ALTERNATING CURRENT LANTERNS [Cn. II 



119. Summary of Chapter II: 

 Do 



i. Connect both supply wires 

 with the lamp; and remember 

 that with the alternating cur- 

 rent lamp it makes no difference 

 which supply wire goes to the 

 binding post of the upper and 

 which to the post for the lower 

 carbon ( 106). 



2. Insert a rheostat or other 

 balancing device along one of 

 the supply wires (fig. 3). 



3. Insert the ammeter along 

 one wire (fig. 2). 



4. Install a double-pole switch 

 before the rheostat (fig. 3). 



5. If the lantern table is on a 

 concrete floor, use a board or 

 insulating mat to stand on and 

 thus avoid possibility of a shock 

 if the metal part of the lantern 

 is touched ( 98, 689). 



6. Feed the carbons nearer 

 together every three to five 

 minutes so that the lam]) will 

 not be noisy or go out or give 

 double screen images. 



Do NOT 



i . Do not fail to connect both 

 supply wires to the arc lamp. 



2. Never try to use an arc 

 lamp without a rheostat or 

 balance. Do not connect the 

 rheostat with both, but with a 

 single wire. 



3. Do not connect the am- 

 meter with both supply wires,' 

 but with one. 



4. Do not install a lantern 

 without a double-pole, table 

 switch which will cut off the 

 current from all the apparatus 

 on the lantern table (fig. 40). 



5. Do not stand directly on a 

 moist concrete floor when oper- 

 ating a magic lantern with an 

 alternating current lamp. 



6. Do not let the lamp go too 

 long before feeding up the car- 

 bons. 



