SCIENCE AND PRACTICE. 409 



nently repaired, the cable was at any rate endowed with a 

 new lease of life, and one renewable to a certain limit, 

 from time to time, as its weak condition interfered with its 

 working. 



Hipp grounded his operation upon the physical facts that, 

 when the the two poles of a battery are plunged into water, 

 the latter is decomposed oxygen being developed at the 

 positive, and hydrogen at the negative pole ; that when the 

 positive electrode consists of a base metal, it is oxidised 

 by the gas formed on its surface, and that the oxide thus 

 formed is a very bad conductor of electricity. Hipp, there* 

 fore, put the positive pole of a battery of seventy-two elements 

 to the Lucerne end of his faulty cable, and insulated the end 

 at Fleuellen ; the loss of current expressed by the deflection 

 of his galvanometer needle amounted at the time to 32, and 

 this lasted during all the first day it was kept on ; the next 

 day the deflection fell to 20 P ; the day following this to 12 Q ; 

 and on the fourth day the loss had decreased to 3^, the 

 battery being kept all the time of the same strength. 



After working three weeks with positive currents, and 

 keeping the battery on in the intervals between work, the 

 loss fell to 1, and the cable was worked through as if np 

 fault existed. 



This method, which might be safely followed with a cable 

 laid in fresh water, would be dangerous with one submerged 

 in the sea. The positive current, in this case, finding a way 

 through the insulator, would facilitate the formation of 

 muriate of copper in the fault. This would partly insulate 

 it ; but being a soluble salt, it would very soon become dissi" 

 pated in the surrounding water, and open the wound again 

 greater than before. Besides, the copper of the conductor 

 would be continually wasted, until continuity were entirely 

 interrupted. To avoid this evil Mr. Yarley suggested laying 

 a pure platinum wire along the strand, which would not be 

 liable to dissolution by the current, and therefore preserve 

 the continuity. Such a proceeding, with the present high 

 sensibility of the receiving apparatus used upon long lines, 

 would be no doubt of immense value, and we may some day 



