[3] Submarine Telegraphs: Their History, Construction, and Working, by Charles Bright, F.R.S.E., A.M. Inst. C.E., M.I.E.E. (London: Crosby Lockwood & Son, 1898.)
[4] B.W.G.—Birmingham Wire Gage.
[5] It was gravely suggested by a prominent naval officer to thread the line through old cannonades lying idle, at Portsmouth harbor. This notion was not taken up; but a light chain twined round the insulated conductor throughout its length would certainly have served the purpose better than the leaden weights, inasmuch as it would have protected the line from chafing, besides being less liable to damage the core.
[6] Some critics had actually supposed that the method of signaling was that of pulling the wire after the manner of mechanical house-bells; and were at pains to point out that the bottom of the channel was too rough for that.
[7] For further particulars, see the Life Story of Sir Charles Tilston Bright. (London: Archibald Constable & Co., 1898.)
[8] It will be readily understood that without this weight, the line would not for certain descend to the bottom—and certainly not in a straight line—in any considerable depths. On the other hand, it would be impossible to recover an effective weight without great risk of breaking the line. For this reason the weight is abandoned, and a considerable number may be found at the bottom of the sea in every quarter of the globe.
[9] These live near the surface of the ocean in myriads upon myriads, incessantly sinking to the bottom as their short life is ended. Thus, in the course of ages, there grows constantly upward a formation similar to the chalk cliffs of England, which contain the identical shells, deposited when this country was submerged far below sea-level thousands of years ago.
[10] In the present day, however, soundings are taken at intervals of about ten miles along the proposed route, and even then submarine hills and valleys are frequently encountered. This is effected by means of the Thomson steam sounding-apparatus, the great feature of which is a fine steel wire (the same as that in the treble notes of a piano) in place of a hempen line of enormous bulk. Nowadays, taking a sounding in the Atlantic occupies well under an hour of time, where by the old method it took at least six hours.
[11] The full particulars of the agreement with the English Government were embodied in a letter from the Treasury (see Life Story of Sir Charles Bright) and form instructive reading even at the present time.
[12] Submarine Telegraphs.