152 ANNUAL OF SCIENTIFIC DISCOVERY. 



INSULATION OF THE ATLANTIC CABLE. 



The "Boston Journal of Chemistry " asserts, on the authority 

 of a gentleman intimately connected with the working of the 

 Atlantic Telegraph Cable, that the insulation is growing montlily 

 more perfect, and that the lirst cable, laid 4 jears since, leaks 

 less than tiie last one. The loss, at the present time, does not 

 YciiQh half of one per cent, upon both cables. This is surprising, 

 and very encouraging to the owners of the line. The extreme 

 cold of the deep-sea basin, in which the wires repose, is favorable 

 to the retention of the electrical impulses in the channel provided 

 lor them. The time consumed in charging and discharging the 

 conductors is a bar to rapid comnmnication ; but this is to be over- 

 come by new methods of insulation. A device has recently been 

 brought fonvard wliieh promises to fully remove tiiis obstacle, and 

 thus enable submarine cables to perform double the work in tlie 

 same length of time. The success of deep-sea cables is now fully 

 assured, and we may look for a large increase in the number dur- 

 ing the next quarter of a century. 



MAGNETISM. 



The French Academy of Sciences has received a paper from M. 

 J. Jamin, in which he shows that magnetism may be condensed, 

 just like electricity. Having, for some special purposes, had a 

 large horse-shoe magnet made, consisting of 10 lamime of per- 

 fectl}'^ homogeneous steel, each weighing 10 kilogrammes, he 

 suspended it to a hook attached to a strong beam, and, luivin;^ 

 wound copper wire around each of the legs, which were turned 

 downwards, he put the latter into commmiication with a batteiy 

 of 50of Bunsen's elements, by which means the horse-shoe might 

 be magnetized, either positively or negatively, at pleasure. The 

 varations were indicated by a small horizontal needle, situated 

 in the plane of the poles. There was, further, a series of iron 

 plates, which could be separately applied to each of the laminaj. 

 Before attaching any of the latter, the electric current was driven 

 through the apparatus for a few minutes, and then interrupted, 

 whereby the magnet acquired its lir.-t degree of saturation, 

 marked by a certain deviation of the needle. One of the iron 

 plates (usually called "contacts") was then put on, and it sup- 

 ported a weight of 140 kilogrammes, A second trial was now 

 made ; and, the current having passed through again for a few 

 seconds, it was found that the horse-shoe would support 300 kilo- 

 grammes, instead of 140. The number of contacts being now 

 increased to 5, which together, in the natural state, supported 

 120 kilogrammes, it was found, after the passage of the current, 

 that they could support the enormous weight of (J80 kilogrammes, 

 which they did for the space of a full week. No sooner, how- 

 ever, were the contacts taken off than the horse-shoe returned 

 to its usual permanent strength of 110 kilogrammes. This 

 tends to show that magnetism may be condensed like electricity 

 for a short period. 



