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IV. "An Account of some Experiments made with the Sub- 

 marine Cable of the Mediterranean Electric Telegraph." 

 By CHARLES WHEATS-TONE, F.R.S. Received March 29, 

 1855. 



The following results were obtained between May 24 and June 8 

 in last year, with the telegraphic cable manufactured by Messrs. 

 Kuper and Co. of East Greenwich, for the purpose of being laid 

 across the Mediterranean sea, from Spezia on the coast of Italy to 

 the island of Corsica. The manufacturers, in conjunction with 

 Mr. Thomson the engineer of the undertaking, kindly afforded me 

 every facility in carrying on the experiments. The short time that 

 elapsed between the opportunity presenting itself and the shipping 

 of the cable for its destination, prevented me from determining with 

 sufficient accuracy some points of importance, respecting which I 

 was only able to make preliminary experiments, but the following, 

 which I was able to effect with the means at hand, may possess 

 sufficient interest to be made public. They present perhaps nothing 

 theoretically new, but I am not aware that experimental verifications 

 of some of these points have been made before. I assume that the 

 reader is acquainted with the experiments of Dr. Faraday described 

 in the Philosophical Magazine, N. S., vol. vii. p. 197. 



The cable was 110 miles in length, and contained six copper wires, 

 one-sixteenth of an inch in diameter, each separately insulated in 

 a covering of gutta percha one- tenth of an inch in thickness. The 

 whole was surrounded by twelve thick iron wires twisted spirally 

 around it, forming a complete metallic envelope one-third of an inch 

 in thickness. A section of the cable presented the six wires arranged 

 in a circle of half an inch diameter, and one-fifth of an inch from the 

 internal surface of the iron envelope. 



The cable was coiled in a dry well in the yard, and one of its ends 

 was brought into the manufactory. The wires were numbered 1, 

 2, 3, 4, 5, 6, and the ends in the well were indicated by an accent ; 

 the ends 1'2, 2'3, 3'4, 4'5, 5'6 were connected by supplementary 

 wires, so that the electric current might be passed in the same direc- 

 tion through all the six wires joined to a single length, or through 



