Mr. J. N. Hearder on the Atlantic Cable. 39 



will yield as many as 20 or 30 minute residual discharges, ex- 

 tending over an interval of half an hour. 



Ha\ang now pointed out what I consider to be the chief sci- 

 entific defects in the Atlantic Cable, I might proceed to describe 

 the means which I have lately introduced for removing them, and 

 obviating the diflSculties which at present lie in the way of the 

 successful construction and working of very long submarine 

 telegraph cables. But I intend this to form the subject of a di- 

 stinct communication ; I shall therefore now proceed to examine 

 the arrangement and peculiarities of the instruments intended 

 to be employed for working through it. 



When intense currents are wanted to overcome resistance, it 

 is necessary to use batteries consisting of a great number of 

 elements ; but as a highly-resisting conductor can transmit only 

 a small quantity of electricity, these elements may be extremely 

 small, and I believe that the batteries usually employed are very 

 much larger than necessary. There are other modes of exciting 

 electricity of high tension, where the quantity effects are not 

 required to be great, such as the secondary current of an induction 

 coil, or the current produced from a magneto -electric machine. 

 I see no reason, however, why, small and inadequate as the 

 Atlantic conductor is, it might not have been worked with an 

 intensity battery of a large number of small plates ; but the 

 electrician of the Company, Mr. Whitehouse, preferred working 

 with electro-magnetic coils, and accordingly conti-ived an in- 

 duction coil for the purpose, having the primary wire outside 

 and the secondary wire within, immediately surrounding the 

 core. 



From a careful consideration of this instrument and its effects, 

 it appears to me open to many objections, both as regards its elec- 

 trical arrangements and mechanical consti'uction ; and the com- 

 paratively small amount of effect produced by it in relation to its 

 magnitude, and the enormous power and gigantic character of 

 the batteries required to excite it, seem to justify these conclu- 

 sions, and to indicate that there are some serious radical defects 

 in the internal arrangement. Judging from the power developed 

 from my own form of the induction coil, I was prepared to expect 

 effects some fifty times greater. When, however, Mr. Whitehouse 

 explained to me that none of the coils had been properly tested, 

 and that some of the largest had even been made and put on 

 board ship without any trial whatever, from want of sufficient 

 time and opportunity, it was easy to understand how apparatus 

 requiring such an intimate and ])rofound acquaintance with the 

 laws of electricity on the part of the inventor, and so much me- 

 chanical skill and judgment added to the greatest familiarity 

 with electrical appliances and arrangements on the part of the 



