420 SIR RODERICK I. MURCHISON'S ADDRESS. [May 25, 1857. 



a capacity of tension if needful to a moderate extent without injury, 

 with cohesion sufficient to ensure resistance to a strain of consider- 

 able amount. 



In the form of cable adopted by the Company,* it is believed that 

 all these conditions are fulfilled. The conducting medium is formed 

 by a strand of seven copper wires ; six of these wires are wound 

 spirally round the seventh, which latter is laid straight through 

 the centre, and the diameter of the entire strand is somewhat less 

 than the eighth of an inch. Around this strand are placed three 

 separate layers of gutta percha, and thus the " core " is formed, 

 which is about three eighths of an inch in diameter. Upon the core 

 the appliances for sinking it and providing against the strain and 

 abrasion incident to the paying it out into the Atlantic are. laid. 

 These consist of a soft bed of hempen twist saturated with tar, 

 which is wound round the gutta percha core, and on the exterior of 

 this is spun, in spiral continuity, eighteen strands of iron wire. 

 This operation completes the cable, the total diameter of which is 

 five-eighths of an inch, and the total length 2500 miles, or about a 

 third of the earth's diameter. The total continuous length of the 

 copper and iron wire employed in its manufacture will be 332,500 

 miles, and if extended in one line would therefore go fourteen times 

 round our little planet. 



The form of apparatus with which it is proposed to project the 

 electric current through a conductor of such enormous iength, has 

 also been specially adapted for the purpose. 



The connection of Great Britain with America by the means thus 

 delineated will, it is trusted, be realized by the end of Augiast in 

 the present year. The magnificent United States' frigate Niagara, 

 commanded by Captain Hudson, will ship her portion of tht cable, 

 consisting of 1500 tons, at Liverpool, and H. M. ship Agamem- 

 non, under Master-Commander T. A. Noddall, will receive an 

 equal amount off East Greenwich. They will then proced to 

 mid-ocean, when they will commence paying out the cable, the 

 Niagara steaming towards the coast of America, and the Aga- 

 memnon returning to England. The Agamemnon has been ]re- 

 ceded by the paddle-wheel steam-frigate Cyclops, for the purpse 

 of taking soundings ; and steps have been taken by the Admira.t;: 

 to secure for naturalists all the materials whether animal or vege 

 table which may be brought up from the sea bottom. Let us 



♦ I am indebted to Mr. T. Holdsworth Brooking, f.r.g.s., for these details. Mr. 

 Bright is the able engineer of the Atlantic Telegraph Company. 



