86 Mr. H. Wilde's Experimental Researches 



that though the conductors were in close proximity to each other, 

 yet no metallic contact between them was established. The in- 

 tegrity of the insulation of these double or twin conductors (as 

 I propose to call them) was examined in air with the powerful 

 current from the 10-inch intensity-armature, and was found to 

 be perfect. These double or twin conductors are represented in 

 fig. 1 1, Plate I., with the ends A, B and C, D carefully separated. 



106. Owing to the great size and good conducting-capacity 

 of the aerial connexions, and of the naked and the tape-covered 

 conductors to be immersed in the canal, the whole of the 618 

 (2 x 140 + 2 x 169 = 618) feet of copper rope, when formed into 

 a complete metallic circuit in air, did not greatly diminish the 

 power of the current from any of the electromotors, except that 

 from the 10-inch quantity-armature, which current, however, 

 after passing through the 618 feet of conductor spread out on a 

 dry boarded floor, was still sufficiently powerful to melt twelve 

 inches of iron wire '095 of an inch in diameter when introduced 

 into the circuit; while the currents from the 5- and 10-inch 

 intensity- armatures, after passing through the same length of 

 conductor, would melt nearly the same quantity of wire as they 

 would in short circuit; and the currents from the 2J-inch ma- 

 chine and the single Grove's cell, after passing through the 618 

 feet of wire rope, would still melt, the former 4 inches, and the 

 latter |- of an inch of iron wire *016 of an inch in diameter. 



107. As this size of iron wire (-016 of an inch in diameter) 

 will be frequently referred to hereafter, it will be more conve- 

 nient to speak of it as the thin wire. 



108. The two naked copper ropes (104) were each coiled into 

 a ring about 2 feet in diameter, with their several convolutions 

 in close metallic contact. The rings were then placed in metallic 

 connexion with the respective ends of the aerial conductors and 

 immersed in the canal, with the planes of the rings opposite to each 

 other, about three feet apart, and perpendicular to the surface of 

 the water. 



109. The disposition of the aerial conductors and electrodes in 

 relation to each other and to the electromotors will be better un- 

 derstood on reference to Plate I. fig. 12, in which E represents the 

 electromotor, F, G its polar terminals, H, I the aerial conductors 

 for establishing connexion between the electromotor and the ring- 

 electrodes K, L immersed in the canal M. The respective ends 

 of the naked copper ropes will be indicated, when necessary, by the 

 same letters (A, B and C, D) as those of the twin conductors, fig. 1 1 . 



110. A tangent galvanometer, or pieces of iron wire of differ- 

 ent lengths and diameters, could be introduced at pleasure at the 

 point N, between the pole G and the conductor H, for the pur- 

 pose of indicating, by galvanometric deflection, or by the heat 



