and will recover about ten[1], when the strain is taken off.’ What a derangement is here! When we look at this, and contemplate the injury hereby inflicted on the materials, we confess that we are not surprised that some of these chains have given way. That any of them should stand after sustaining such an injury, furnishes, perhaps, the strongest evidence that could be adduced, of the superiority of iron over hemp for the purposes of a cable.
“It is the more surprising that Captain Brown should have fallen into this mistake respecting elasticity, having himself detected and exposed its fallacy as to hemp: ‘There cannot, says he, ever be any certain advantage deduced from the portion of elasticity which cordage is known to possess; for the force which caused its extension may be extended for a considerable time after the cable has been stretched to its utmost limits:’ – of course, under a further strain it must break. He might have added, that every lengthening of a rope by strain is accompanied with the rupture of a certain number of its fibres: every repetition of the force ruptures more of them, and thus in time it becomes unserviceable. There is no stretching without this partial rupturing; and it is equally true, that no change in the relative position of the particles of matter in the link of a chain can be induced without a proportionate rupturing, injurious to its strength, taking place, though not perceptible to the eye.
“Were it even true that the giving of a hempen cable was in its favour, the iron cable, from its superior gravity and the consequent weight of its curve, (an advantage justly appreciated by Captain Brown,) possesses more capability of giving (i.e. of lengthening the distance between the points of resistance) by the first effect of every strain, namely, an effort to straighten the chain, than any cable can by stretching. The elasticity, therefore, which Captain Brown gives to his chain, presents no one benefit to compensate in the slightest degree for the injury done to the iron, by giving it a form unfavourable to the resistance of violence
“The defect, and it is a most serious one, which attaches to the construction of Captain Brown’s chain, has been most happily obviated in another mode of construction, for which the inventor, Mr. Thomas Brunton, of the Commercial Road, has likewise obtained a patent. In Mr. Brunton’s chain cable, that arrangement which can most effectually resist every solicitation to change the form of any of the links – or, in other words, that form of link which shall present the substance of the iron in the best possible position for bringing the whole mass into equal action when assailed by an external force – has been most successfully adopted. * * * * * *
“The public, we think, have been laid under great obligations both to- ↑ Observations on the Patent Iron Cables invented by Captain Samuel Brown.
