Section 28. Modifications of the Apparatus. 



65 



by brass pieces bolted to the inner sides (A lf AS) of the bath, and is 

 rotated by means of two cranks C 1 and C 2 , at right angles to each other, 

 and of the eccentric rods a x and a 2 , which extend up through the cover 

 of the bath. The ends of these rods are grasped in the fingers, and rota- 

 tion is secured by alternately pulling and pushing them. 



Electrical connection with the outside of the bomb is secured through 

 the carriage, the supporting piece B, and the copper wire W , which is 

 brazed into the latter. Connection with the lower electrode is secured 

 through the flexible copper lead-wire L lf the insulated steel ring P 1} into 

 which the lead-wire is brazed, the insulated brass piece D u on which the 

 ring P 1 rests, and the copper wire W x , which is brazed into Z), ; and, simi- 



* larly, the upper electrode communica- 

 tion is through L 2 , S, P,, D 2 , and W 2 . 

 The method of insulating P 1 from P., 

 and P 2 from R will be clear from the 

 diagram. In this diagram .1/ denotes 

 mica, and K is simply a checknut to 

 keep the rings from turning on the 

 shaft. 



As the insulated pieces D 1 and D 2 

 have to support half the weight of the 

 bomb, they, in turn, have to be securely 

 fastened to the inner wall of the bath. 

 The method for securing this support 

 and at the same time insulation by 

 means of mica is shown in fig. 15, in 

 which the lettering is the same as in 

 fig. 14. 



To be sure of low resistance con- 

 tacts the ends of the steel shaft and 

 the brass supporting pieces must be 

 thoroughly cleaned before the bomb is 

 put into the bath. 



For convenience in manipulation, 

 Fi 8 . 15. the carriage, 5\iv?5\,, is supported when 



not in the bath, by resting the ends of the shaft in a wooden U-shaped 

 stand. The bomb when ready is screwed to the carriage and the flexible 

 lead-wires bolted to the electrodes. It can then be picked up and lowered 

 into the bath by means of a double-pronged hook which slips into two 

 brass eyes, E x and E 2 , attached to diametrically opposite points of a flat 

 brass ring, Q, which is fastened by means of three thumb nuts to the large 

 nut of the bomb. The bomb is afterwards removed from the bath in the 

 same manner, and is hung up upon the hook before a fan to cool. 



