Wire-drawer's bench
(Chambers's Encyclopedia, 1870)

Dr. W. POLE, honorary secretary, said that as the discussion had diverged to a certain extent into the mysterious properties of steel generally, the members might like to know a fact that had been lately communicated to him by Dr. Percy, as to the extraordinary qualities shown by steel in the form of wire. Dr. Pole had occasion in 1862 to make some experiments on the strain of piano-fortes ; and he found that the steel wire used for them showed a most remarkable tensile strength. It was well known that if a wire of a certain length and a certain weight sounded a certain note (giving a certain number of vibrations per second), it must be subject to a certain tension ; and testing in that way it was found that the piano-forte wire stood a strain from 100 tons to 120 tons persquare inch. He had mentioned the fact at this Institution, [Minutes of Proceedings Inst. C. E., vol. xxi, p. 242 ; vol. xlii, p. 202.], but at that time no one had ever heard of such a strain being withstood by steel in any form, and the assertion was doubted, even by no less an authority than Sir Joseph Whitworth. It was, however, tested and found to be true. Dr. Percy, who had taken a great deal of interest in the matter, had recently told him that he had some steel wire which was actually standing, as tested in the machine at Woolwich with great care, the extraordinary strain of 154 tons per square inch, and he hoped that Dr. Percy would publish the particulars. In corroberation he had heard from Messrs. Broadwood that during the last ten or twenty years they had found that piano-forte wire had been greatly increasing in strength. It was a remarkable thing that steel in that form should possess such extraordinary and almost unheard-of tenacity. He ought to add that the wire alluded to was by no means hard and brittle, as steel of very high tensile power often was. It was subjected in its use to sever usage. It was wrapped round a small pin which served for tuning, and it was turned into loops and subjected to twists, showing that it had a certain amount of ductility. The strings also receive violent blows, which, however ,appeared to do them no damage. Dr. Pole also thought it right to mention another remarkable quality shown by steel wire, namely, the very high range of its elastic limit. A piano-forte string was, when in use, strained almost to its breaking point, and yet the elasticity remained perfect, as was shown by the fact that the string would, when once tuned, stand in tune, i.e., would receive no permanent elongation, for an indefinite length of time. Dr. Pole conceived that a form of the metal which showed these extraordinary qualities was well worth study, and that if the conditions which produced these qualities could be exactly determined, the investigation might throw more light on the properties of steel generally. (Minutes of Proceedings of the Institution of Civil Engineers)

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