SUBMARINE CABLES, 



effect might be contrived upon the principle suggested by Davy, 

 for the preservation of the copper sheathing of ships, by investing 

 the cable at certain intervals with a thick coating or glove of zinc, 

 which would increase the efficiency of the thinner coating of that 

 metal given to it in the process of galvanisation.* 



To this practical men who have had as much experience as is 

 compatible with the recent date of these novel and extraordinary 

 enterprises, reply that the results of their observations give no 

 ground for apprehension of any injurious effects from tidal or 

 tempestuous action, and that the fine iron used in the wire 

 is not affected by sea water, as larger masses of coarser iron, 

 such as anchors, are. They cite as proof of this, the slightly 

 decayed state in which nails and small fire-arms have been 

 found when recovered from vessels long sunk. They further 

 state that the tar contained in the layer of hemp within the 

 protecting wires acts as a preservative, whether the wires be 

 galvanised or not. It has been found for example that, in the 

 case of the submarine conductor between Donaghadee and Port- 

 patrick, a perfect concrete of tar and sand has been already 

 formed, upon which masses of shell-fish attach themselves at 

 all parts that are not buried in sand, and it is apparent that 

 in a few years a calcareous deposit will be formed around it, 

 which will cement it to the bottom, and altogether intercept the 

 action of the sea water. 



90. In the deposition of submarine cables great care should be 

 taken to select suitable points on the shore for beaching them. 

 Sandy places are always to be sought. If this precaution be taken, 

 it is affirmed that they are not subject to tidal action. A cable 

 was partly laid by the Magnetic Telegraph Company in 1852 

 near Portpatrick (83), but abandoned in consequence of the vessel 

 employed to deposit it being exposed in the process to a violent 

 storm. The wire was left exposed upon the beach down to and 

 beyond low water mark, and was in June, 1854, still in a perfect 

 state, the galvanised iron wires, even to their zinc coating, being 

 absolutely in the same state as when they were deposited. 



91. It is contended by practical men that the great and only 

 risk of failure in the submarine cables is from defects produced in 

 the process of their deposition, or from original faults in the prin- 

 ciple of their construction. 



The greatest care is necessary in conducting the process of 

 delivering out the cable into the sea, or "paying it out," as it is 

 technically called. All sudden bending of the cable is to be 

 especially avoided. "Kinks" or "hitches" are apt to occur in 



* Potullet, "Traite de Physique," vol. I p, 799, Ed, 1853. 



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