84 Mr. H. Wilde's Experimental Researches 



who thinks that the anomalous results obtained by Matteucci 

 may be accounted for by supposing that the molecules interposed 

 between the two electrodes, not being so numerous when the 

 latter are near together, may constitute the electric chain by the 

 mutual neutralization of their opposite electricities, which is pre- 

 ceded by their polarization; but when the electrodes are very 

 distant from each other this communication can no longer take 

 place, and they are then discharged, by means of the bed with 

 which they are in contact, into the entire mass of the terrestrial 

 globe*. From this explanation it will be seen that De la Hive, 

 in common with Matteucci, holds the opinion that a diminution 

 of the distance between the electrodes in contact with the earth 

 is attended with an increase of resistance to the passage of the 

 current from the electromotor. 



96. This brief historical sketch of the present state of know- 

 ledge on the function which the earth performs as a conductor 

 of electricity, as made known by those physicists who have pre- 

 ceded me in this research, will, I think, lead to a full compre- 

 hension of my own experiments in the same direction, and of the 

 new phenomena which form the subject of this paper, 



97. The principal electromotors which I employed were the 

 machines described in the First Series of these researches, and 

 consisted (1) of a 2^-incb magneto-electric machine (58) worked 

 by hand. This machine would melt four inches of iron wire '025 of 

 an inch in diameter in short circuit, i. e. when the iron wire was 

 directly interposed between the polar terminals of the machine. 



98. (2) A 5-inch electromagnetic machine excited by a 2^-inch 

 magneto- electric machine (63). — This machine was furnished 

 with two armatures, one for the production of " quantity," and 

 the other for the production of " intensity " effects. The quan- 

 tity-armature would melt fifteen inches of iron wire *075 of an 

 inch in diameter, and the intensity-armature thirty- six inches of 

 iron wire '035 of an inch in diameter, in short circuit. 



99. (3) A 10-inch electromagnetic machine (66) excited by a 

 3J-inch magneto-electric machine. — This machine was provided 

 with the quantity- and intensity-armatures before described (70), 

 (71), (72). The quantity-armature of this machine, when ex- 

 cited by the 3J-inch machine, would melt about fourteen inches 

 of iron rod \ of an inch in diameter, and the intensity-armature 

 seven feet of iron wire -J^ of an inch in diameter. 



100. (4) A well-excited Grove's cell, the platinum of which was 

 6J x 3 inches. — This electromotor would melt (making allowance 

 for the heat abstracted by the polar conductors) seven-eighths of 

 an inch of iron wire # 035 of an inch in diameter. Two, three, 



* Treatise on Electricity, by Aug. De la Rive, vol. iii. note to p. 448. 



