MECHANICAL PROPERTIES OF THE PROPOSED ATLANTIC CABLE. 409 



they vary considerably as regards strength, ductility, &c. Several of these 

 cables are of a high order of merit, and well entitled to special notice as they 

 reached the required point of strength — a quality of great importance in cables 

 for submergence in deep water. 



Table of the Tensile Breaking-strain of Atlantic Submarine Electric Cables, 



as supplied by different manufacturers. 



Summary of Results. 



Number 

 of 



detailed 

 eiperi- 

 ment. 



12 



I 



II 



2 



3 

 4 

 5 

 6 



7 

 S 



Description of Cable. 



Messrs. Silver & Co. 

 „ Silver & Co. , 

 „ Duncan ... 



Allan 



„ Allan 



„ Hall & Wells 



„ Siemens & Co., b. . . . 



„ Siemens & Co., a. . . . 



„ Glass, Elliott 



„ Glass, Elliott 



„ W.F.Henley 



„ W.F.Henley 



„ Glass, Elliot, & Chat- 



terton 



Breaking-weight. 



lbs. 



130 



354 

 2146 



2258 



2glg 

 4946 



5394 



5730 

 7690 

 7690 



9594 

 12786 



H783 



tons. 



•058 

 ■158 

 •958 



i"oo8 



1-258 



2"007 



2 '40 8 



^■553 



3 '43 3 

 3'433 

 4-283 

 5-708 



6-600 



Diameter 

 of Cable, 

 in inches. 



■35 



•35 

 ■77 



-67 

 ■76 

 •77 

 ■77 

 i-io 

 i-io 



•85 



■8s 



IIO 



Elongiition 

 in S feet 

 length of 



Cable, 

 in inches. 



17-10 



6-75*] 

 1-67 

 2-16 

 2-6o 



2-85 



377? 

 4-10 



i-8s 



2-72 



3-57 



Elongation 

 per unit 

 of length 



-t 



•1781 



•0703 {") 



•1380(6) 



0169 (e) 



■0225 



-0270 



-0296 



■0392? 



•0427 



•0191 (d) 



•0339 (c) 



•0449 



(d) Without outside covering. 



(e) The completed cable. 



(a) For out.side steel wires. 

 (6) For copper wire.s. 

 (c) The completed cable. 



From these considerations it was deemed advi.sable to select a description 

 of cable containing this clement, and all the requirements to meet the con- 

 tingent forces to which it might be subjected. With these impressions on 

 the minds of the Committee, it was found desirable to select that of Messrs. 

 Glass, Elliott & Co., which stands highest in the order of strength in the 

 foregoing Table, and from the re.sults in p. 410, deduced from subsequent 

 experiments on upwards of forty specimens manufactured by the same firm. 



In this inquiry it will be observed that upwards of forty specimens of 

 cables have been tested in their finished state, and this might have been 

 sufficient for the Committee to determine the best description of cable ; but it 

 was deemed ad%-isable to investigate still further, not only the cable a.s a 

 cable, but to test experimentally each separate part, in order that every 

 security should be afforded as to the strength and quality of the material to 

 be employed in the construction. The whole of the specimens submitted by 

 Messrs. Glass, Elliott & Co., were composed of the same sizes of conducting 

 wire insulated within alternate layers of gutta-percha and Chatterton's com- 

 pound, which formed the core of each. Surrounding this core, were lapped, 

 in a spiral direction, nine and in some cases ten wires, of -089 to -098 inch 

 diameter ; and each wire was covered with Manilla-yarn, or St. Petersburg 

 hemp, saturated with tar and other materials. Now, as these covering wires 

 constituted the principal strength of the cable, it was found desirable to test 

 them separately, for the purpose of ascertaining their tenacity, ductility, 



* Tliis elongation refers to the inside strand of Me-ssrs. Allan's cable, 

 t The elongations of Messrs. Silver and Co.'s Cable, as given in the detailed experi- 

 ments, are not reliable. 



1864. 2 E 



