88 Mr. H. Wilde's Experimental Researches 



tors themselves (106), or to any fault in the connexions, was at 

 once made evident by joining together the distant ends C, D of 

 the extended conductors, when the iron wires introduced at N 

 were immediately melted. 



118. In order that a discharge of electricity through the ex- 

 tended conductors K, L might be obtained, it was essential that 

 the connexion between the ends A, B and the aerial connexions 

 H, I, although immersed in the water, should be entirely me- 

 tallic ; for when one of these ends, A, was separated from the 

 other end, I, by only the thickness of a piece of tape, no heating 

 effects sensible to the touch were produced in the thin iron wire 

 at N by the powerful current of the 10-inch intensity-armature, 

 even when the distant extremities C, D of the conductors were 

 joined together. 



119. Though the current from a single Grove's or DanielPs 

 cell was not powerful enough to heat sensibly any thin wire at 

 N when either of these cells was placed in connexion with the 

 extended conductors with their ends C, D disconnected, yet an 

 amount of current was always found passing through the con- 

 ductors sufficient to produce a deflection of the galvanometer 

 at N. Moreover, when contact between the Grove's or DanielPs 

 cell (or one formed of zinc and platinum, excited by dilute sul- 

 phuric acid) and the extended conductors was maintained for a 

 few moments and then broken, the galvanometer always indicated 

 a counter current from the extended conductors about half the 

 strength of that previously passing from the electromotor. 



120. That none of the effects of conduction and resistance of 

 the terrestrial bed, as manifested by the heating or non-heating 

 of the wires at N, were brought about by the exercise of any 

 mutual influence of the conductors upon each other through the 

 intervening body of water, or, again, by any change in the elec- 

 tric condition of the earth taking place by reason of a change in 

 the linear distance of the electrodes from each other, was proved 

 by the following experiments (122, 123) (137-139). 



121. One of the aerial copper-rope conductors, H, was extended 

 upon insulated supports along the side of the canal to a point 

 300 feet beyond where the other aerial conductor, I, entered the 

 canal, so that the electrodes or conductors in the canal might 

 now be 300 feet instead of a few feet from each other. In con- 

 sequence of the great thickness and good conducting-capacity of 

 the aerial connexions, they offered, practically, no resistance to 

 the passage of the currents from any of the electromotors used 

 in the experiments. 



122. On repeating, in the same order, all the preceding ex- 

 periments with the submerged conductors, both in their coiled 

 and extended form, results were obtained from the electromotors 



