332 Transactions. — Miscellaneous. 



buoy in the sea, and attached to it was the end of the cable 

 laid by the " Hooper " on the previous voyage. We tlien 

 proceeded up the coast, and found a similar buoy supporting 

 an end of cable. This was the hundred miles of shore end 

 which had been laid by the steamer which left London a few 

 weeks before ourselves, and which \ve had spoken with off 

 Cayenne. We anchored close by this buoy, hauled the end of 

 the cable on board, joined it to a section two or three hundred 

 miles long in one of our tanks, and proceeded to lay the latter 

 section down the coast to Cayenne. 



During the voyage out, as during manufacture, each 

 length of the cable was subjected to one or two electrical 

 tests daily, but during laying the cable was subjected to a 

 very rigorous continuous test. In this way, if anything 

 occurred to cause a flaw in the insulator, it would be dis- 

 covered in a moment. At the same time an arrangement 

 was made for a signal to be sent from the shore station at 

 regular intervals of five minutes, to insure that there was no 

 interruption of the copper conductor. 



To prevent this latter test from interfering with the former 

 the signals are sent by what is known as an " induced cur- 

 rent." The cable is connected to a condenser at each end — 

 that is, one condenser is at the shore station, the other in the 

 testing-room on the ship. The cable, therefore, is completely 

 insulated. It is charged by a battery of about a hundred 

 cells, and the amount of loss of charge in a given time de- 

 termines the state of its insulation. Whether charged or not, 

 if contact is made between the shore battery and the con- 

 denser a momentary current is induced in the cable, which 

 wT)rks an instrument in the testing-room on the ship. I wish 

 to direct attention to this point, as I shall have occasion to 

 refer to it again in speaking of the work of signalling through 

 the cables. The condensers employed consist of a number of 

 sheets of tinfoil separated by paper soaked in paraffin. The 

 tinfoil projects at the end of the paper, one set, say numbers 

 1, 3, 5, &c., at one end, the other set, numbers 2, 4, 6, &c., at 

 the other end. Each set is connected to a binding-screw on 

 its own side of the condenser. In this way two large metallic 

 surfaces sepai*ated by a thin dielectric are obtained, and one 

 surface receiving the slightest charge induces a momentary 

 current in the other surface, and in any conductor connected 

 with it, though no current passes across the paraffin dielectric. 



The actual laying the cable is simply letting it run out of 

 the ship into the sea. As the ship goes on some of the 

 cable is left behind. The running-out must be controlled by 

 machinery to prevent it running out too fast, which would 

 waste the material, as also to insure it being paid out fast 

 enough, otherwise the ship might go on and the cable be 



