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LVL On the Influence of Proximity of Mass upon Electric 

 Conduction-resistance. By Dr. G. Gore, F.R.S.* 



IN a previous research on the Influence of Proximity of 

 Substances upon Voltaic action (Phil. Mag. June 1897), 

 I have shown that the presence of a mass of a heavy substance 

 near one of the electrodes of a voltaic cell alters its electro- 

 motive force ; and as I have since then made a very tedious 

 research to determine whether the same influence affects the 

 electric conduction-resistance of metal wires, I beg leave to 

 describe, in the briefest possible form, the general arrange- 

 ment adopted for testing the question. 



The apparatus employed consisted of an Elliott's differential 

 galvanometer ("No. 96" in their catalogue), having a 

 resistance of " 3140 ohms w in each coil, and a six-inch cube 

 of lead weighing nearly eighty pounds divided in two halves 

 vertically, and having spaces cut out of its opposing surfaces 

 to receive a coil and thermometer. Two coils were employed, 

 each being about f inch diameter and 2 J inches long, 

 the insulated copper wire upon each being *002 inch diameter, 

 and having a resistance of "7432 ohms at 15°5 C." Two 

 similar and very sensitive thermometers were also used, read- 

 able to a one-hundredth of a C. degree, and verified at Kew. 



Sufficient uniformity of temperature of the coils and 

 thermometers was secured by enclosing them in a nest of 

 five wooden boxes with intervening layers of cotton -wool and 

 sheets of brightly tinned iron, with layers of flannel outside ; 

 the inner box contained two smaller ones, 6 inches square 

 and 3 inches apart, to contain the cube of lead, the 

 comparison coils, and thermometers. The nest of boxes was 

 placed in a carefully selected situation, so that the average 

 temperatures of the thermometers when in the two small 

 boxes were as nearly as possible alike. 



Equal rates of transmission of temperature from the 

 external atmosphere to the centres of the small boxes when 

 the leaden cube was in place, so that each thermometer 

 arrived at a maximum or a minimum at the same time, were 

 ultimately secured by lining the entire surface of the empty 

 box with plates of paraffin one inch thick. 



The coils employed consisted of the pair of copper ones 

 already mentioned ; a second ditto about 3^ inches long, 

 wire *003 inch diameter, and resistance about 350 ohms ; a 

 third pair about 5£ inches long, wire '003 inch diameter, and 

 resistance about 350 ohms ; and a fourth of aluminium wire, 

 5-J- inches long and j inch diameter, wire '003 inch diameter, 

 and resistance of about 1800 ohms. The covered wire upon 

 all the coils was carefully insulated with paraffin. 

 * Communicated bv the Author. 



