CABLE 



567 



figure of a shackle with links, (fig. 323) : at B is seen the aperture at right angles to 

 the bolt F, (of oval iron) through this channel, cut through the shackle and the bolt, 

 a tapering but not quite cylindrical steel 

 pin, fits exactly ; but does not quite pro- 

 ceed through the iron ; it is shown at 

 gg. Various plans used to be resorted 

 to before this final preference ; for the 

 steel pins, of whatever form, got loose 

 by repeated tapping on the rocky bot- 

 tom, or the links upon each other. 

 Mr. Lenox succeeded in cutting the 

 cavity at E of the form of a hollow cone, 



and to complete the fastening, a pellet 

 or cylinder of lead that will just allow 

 insertion at E is driven, and then by 

 repeated blows the lead is made to fill up 

 the cavity, the superfluous quantity of lead being cut off by the hammer at a. To re- 

 lease the bolt it is only necessary to find the small space at the small end of the steel 

 pin, to insert a punch, and then, with a few blows, the steel pin gg is driven out of 

 its conical bearing, and its flat top and cutting edges enable it to emerge again at E. 

 Being forced out, the bolt F is taken out, and the chain severed if required ; the 

 aperture at E can be cleared of its lead by a proper cutting-out tool, and the steel pin 

 replaced to make all fast. 



This operation can be effected on the darkest night ; the sailor can sever the chain 

 cable, and thus when one vessel is driving down upon another, more chain may be 

 attached to the cable severed, and no harm done ; while with hempen cable it might 

 be found more than difficult, and even impossible, to cut them in time. 



All the principles involved, and perfection of practice, in making chains and chain 

 cables, have recently been deeply considered and fully verified by the firm of Brown, 

 Lenox, and Co., Millwall, who, for the purpose of obtaining comparative results up to 

 the greatest links required for the ' Leviathan ' now the ' Great Eastern,' selected 

 iron of the same identical quality and worked it into rods, links, and chains. The 

 progression of resistance to increased strains, by increase of mass of iron, with all the 

 influences of variation of make, flaws in the material, and other circumstances insepar- 

 able from practice, were thus matters of critical experiment. 



Commencing with \ inch chain, and trying four links of small chains up to 2|ths, being 

 the largest diameter of round iron for the greatest cable links ever hitherto made, 

 being those for the sheet anchor of the ' Leviathan,' taking the breaking strains, and 

 reducing all the links to the proportion borne upon a circle |th of an inch in diameter, 

 the minimum breaking force was 796'25 Ibs., and the maximum 1052'8 Ibs. 



Sometimes the fracture was found to be dependent upon flaws, sometimes from 

 over heating, or unequal heating, and other practical causes ; but the whole series of 

 experiments was important and interesting. 



The iron lengthens to the intense strains employed, long before fracture. The 

 comparison of actual extension, while under enormous force at ordinary temperatures 

 was ascertained by the following impressive. experiments : 



The ' Leviathan,' second size cable of 2f diameters of iron employed in the links. 

 Three links measured 35^ inches by strain of 10 tons (of course it requires power to 

 extend them fairly). 



At 50 tons .... stretched \ of an inch 

 85 



(Proof) 



And broke 



110 

 124 

 140 

 150 

 160 

 170 

 180 



A few links of the best bower anchor cable of tho ' Leviathan ' taken, proved, and 

 destroyed. 

 Three links measured at 15 tons 39 inches. 



At 75 tons .... stretched | of an inch. 



125 , ,;. \ If 



(Proof) 148| 2j 



160 , \^\ 3 



170 , 8} 



