678 



PROCEEDINGS OP THE AMERICAN ACADEMY. 











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Figure 4. 



wooden cover of the box which contained the tanks, the leads from the 

 inside being insulated in glass tubes, so that there would be no chance of 

 their touching the sphere at any point except where they were attached. 



These leads were brought to two mercury cups which could be con- 

 nected directly to the galvanometer. 



The Beckman thermometers were so placed that they came in contact 

 with the sphere where the nickel wires were attached. 



