1851 Great Exhibition: Official Catalogue: Class X.: William Thomas Henley
428. HENLEY, WILLIAM THOMAS, 46 St. John's Street Road, Clerkenwell — Inventor and Manufacturer.
Large permanent horse-shoe magnet, weighing 6.5 cwt.
Patent electric telegraphs, worked by the magneto- electric current.
Magneto-electric machine, illustrating the application of the electric current derived from magnets, to the purposes of electro-chemical decomposition, electro-metallurgy, etc.
The telegraphs have been tested in the worst insulated line in the country, during the most unfavourable weather, and found to work any distance that it was possible to try them, without any diminution of their power. Working without the aid of a voltaic battery, they are always ready for use, without any preparation or expense. Fig. 1 represents the telegraph with its cover, as in use; fig. 2, the same with its cover removed; each consists of two parts, one for producing electricity, the other for receiving it, and indicating the signals; the parts of each telegraph are alike. The first part consists of two compound bar magnets A A, the ends of each being capped with soft iron, to bring the influence of all the plates to any particular point. B B, two armatures, wound with fine-covered copper wire, each placed on a separate axis, and moved by the levers C C, seen projecting through the case in fig. 1; the ends of the wire are carried from the armature through the pieces of ivory in the axle to the wood base, and from thence to the distant instrument, every motion of the lever and armature producing a current of electricity, the downward motion giving a current in one direction, and the upward motion a current in the opposite. The second part of the apparatus consists of a dial, containing the alphabet and certain marks corresponding to the motions of the needles on the face of the dials; for instance, opposite the letter A is seen a single mark inclining to the left, signifying one motion of the left-hand needle; the letter B, two marks; letter C, three marks, signifying three motions of the same needle; the letter D, one mark to the right; E, two; and F, three, G, one right and one left; L, one left; and once both needles together, and so on. Under the dial are placed two electro-magnets D D, each having four poles, formed by two semicircular pieces of iron with a magnetic needle, suspended freely within, placed on the same axis as the corresponding needle, or pointer, seen on the dial. The downward motion of the lever deflects the corresponding needles of all the instruments that may be included in the circuit, as well as its own; the needles remain so, until the lever is allowed to return by the force of the spring E, when the needles all return to their position, and this taking place with certainty, although the instruments may be at any distance.
The current obtained from the apparatus represented in fig. 3 is very powerful, and capable of producing electrochemical decomposition, and all the effects obtained from a powerful voltaic battery. The horse-shoe magnet A, with the 'evolving armature B, formed of hoop-iron, is placed on the mahogany case C, and the whole fixed on the iron framework, on which is suspended the large wheel and treadle, for giving motion to the armature by the pulley D; the magnet has soft caps, and is arranged the same as the telegraph, so that the poles of the magnet are always connected with some part of the iron of the armature, and by that means it always retains its power. The two springs B E rub on the breakpiece F, which is so arranged that the current flows in one direction; the knob G moves a slide to divert the current to the mercury cup H for showing the spark; the cam I moves the point on the spring in and out; the other knob is to make a shock with the two terminals L L.
Electro-magnet capable of sustaining, when excited, 4 tons; the sphere of attraction extends much further by being made of iron hooping.
Large steel permanent magnet, weighing 6.25 cwts., capable of sustaining about 1 ton.
[The received theory of magnetism is, that the attracting power of the bar of steel, which we call a magnet, is due to the circulation of electric currents around the bar. It was discovered by Faraday, that when a metallic mass is moved in proximity to the poles, a current is induced in it: upon this principle magneto-electric machines are constructed. The soft iron armature, or keeper of the permanent magnet, is fixed on an axle, which is made to revolve by some mechanical contrivance, so that a continued and rapid reversal of its poles takes place. By this alone a magneto-electric disturbance is effected; but for the purpose of accumulating the force, coils of copper-wire are fixed on the armature, and every time they approach or leave the poles of the magnet in the course of rotation, an induced current passes through the wire, and the reversal being extremely rapid, though the current is only instantaneous, the result is what may be regarded as an uninterrupted stream of electricity.
The magneto-electric machine was first employed for telegraphic purposes, by Professor Wheatstone. The battery is however usually preferred in this country. R. H.]