The solution of this question must therefore be found in adding mechanical strength externally to the core, by surrounding it with such materials and in such a manner as to relieve it from all that strain which it will unavoidably meet in depositing it in its required position. In the case of the original Atlantic Cable this was attempted by first surrounding the core with tarred hemp, which in its turn was enveloped spirally by eighteen strands of iron wire; each strand consisting of seven No. 22½ gauge wires. The entire weight of the Cable so formed was, in air 20 cwt. per knot, and in water 13·3 per knot. Being capable of bearing its own weight in about five miles perpendicular depth of water, and the greatest depth on the route being two-and a half miles, its strength was calculated at about as much again as was absolutely requisite for the work. This was thought at the time to be a sufficient margin, and certainly in 1858, owing to the greatly improved machinery employed, this Cable was payed-out with great facility and without undue strain, although portions of it had been lost by breaking during several previous attempts in the same summer. Subsequent investigation and experience, however, led to the conclusion, that in respect, not only to its mechanical properties, but especially with regard to its relative specific gravity, and to other points in its construction, the Cable of 1858 was very imperfect; and, with a view to ensure every practicable improvement in the structure of their new line, the promoters of the undertaking, so soon as they found themselves in funds, during 1863, issued advertisements with a view to stimulate inquiry into the subject, inviting tenders for Cables suitable for the proposed work. The specimens that were sent in, as the result of this public appeal, were submitted to the scientific advisers of the Company, who, after careful experiments with all the specimens, unanimously recommended the Atlantic Company to adopt the principle of the Cable proposed by Glass, Elliot, & Co., whose experience and success in this description of work are well known. The Committee, however, stipulated that they should settle the actual material of which the Cable was to be ultimately composed, and that these should be carefully and separately experimented on before finally deciding upon it; and in consequence of this stipulation upwards of one hundred and twenty different specimens, being chiefly variations of the principle adopted by the Committee, were manufactured and subjected to very severe experiment, as were also the various descriptions and quantities of iron, hemp, and Manilla proposed as components of these respective Cables. The result of it all was that the Committee recommended the Cable that was adopted as being, in their opinion, “the one most calculated to insure success in the present state of our experimental knowledge respecting deep-sea Cables,” taking care