Fig. 5 is a cross section of our edge-railway through the middle of one of the chairs a, and across the ends of the two adjoining rails, which are connected by a transverse pin; c is the stone support or sleeper.
Fig. 6 is a cross section of the rail a, at the centre, and shows the supports at the farther extremity.
Fig. 8, in the subjoined cut, is a view of the cast-iron wheel with the malleable iron tire. This wheel is made with curved spokes, as shown at a a a, and with a slit or aperture in the rim, shown at b, into which a key is inserted. The reason of this is, that on the application of the hot tire, the cast metal expands unequally, and the rim is liable to be cracked, and the rims drawn off, unless the first is previously slit or opened, and the latter curved, which allow them to accommodate themselves to the increased diameter of the wheel; by this formation of the wheel, the tire may be placed on when cold, and keyed up afterwards.
Fig. 9 is a cross section of Fig. 8, through the centre. a a show the tire; b b the metal rim. This cast metal rim is dovetailed; so that when the tire, which is dovetailed to suit it, is put on hot, it contracts, and applies itself to the rim with a degree of adhesion which prevents its coming off from the motion of the wheel on the railway. This wheel is of the form to suit an edge-railway; and to make it answer for a plate-rail, it only requires the rim to be flat.
Fig. 10 is an end view of Fig. 8 without the malleable iron tire.
The same patent comprises improvements in "rolleys" or tram-wheels, and in tram-plates. The first consists in the combination of cast and wrought-iron, after the same method as already described with respect to the larger or edge-rail wheels; and the second consists in some judicious modes of fixing the ram-plates to the chairs, through the means of tenons and mortices, so that the ends of the rails are kept firmly in their places.
The transit of coals from the mines to the place of shipment added so much to their cost, that the owners were naturally solicitous to adopt any improvement calculated to lessen it. And the great ameliorations introduced by Messrs. Losh and Stephenson, just described, were of so decided a character, as to become very generally preferred in the collieries of the north; where they continued in use for many years. There was, however, an unquestionable defect in the material used. Cast-iron, although it offers great facilities in producing the desired shapes to resist strains; to economise metal in those parts where much strength is not required; and to afford the most convenient adaptations in fitting together, can never be entirely depended upon, until certain and easily practised means shall be discovered of expelling the air contained in the moulds. From the casting's being often blown in invisible places, frequent breakages were unavoidable, from this cause alone; to which may be added, the derangements of the substructure of the line, which, however well executed, is always taking place in different parts, according as they may be subjected to the various disturbing causes; such as wet, friction, concussions, etc, altogether producing, fa extensive lines, a very serious amount of breakage, and a heavy expense for repairs; nevertheless, previous to Messrs. Losh and Stephenson, the expense of repairs was much greater.
Although the rails in general use were for the most part of cast iron, there were some of malleable iron, made of the ordinary rectangular figure by rolling; which latter were liable to be rendered unserviceable by becoming bent. To remedy this defect in the malleable, and the liability to break in the cast iron, Mr. John Hawks, of Gateshead, Durham, took out a patent in the year 1817, "for a new method of making rails," in which the metal in both its states was combined. The specification states, " Instead of making the rails or bars of cast or malleable iron, as those now in use are, they are a compound of malleable and cast iron, so connected as to be stronger than if made of either kind alone. The surface is formed of cast iron, and the back, or under part, of malleable iron, joined together and formed when the metal of the former is in a fluid state; and they become so inseparable that the cast iron may be broken at the nearest possible distances; indeed, even inch by inch, which is scarcely possible to be occasioned by accident, and the rail will remain sufficient for the purposes of a railway; at least, till it suits the convenience of the workmen to replace it, without interruption to the concern in which the railway may be used: and as a loss by a broken rail of this invention will be less than one in common use, the expense, although it may be a little more in the first instance, will be considerably less in the end, as the malleable iron may be used again, or as the old iron will be of much more intrinsic value than the other."
The modes of combining cast and malleable iron together in the rails are various; but that which Mr. Hawks preferred as affording the best security for their being firmly fixed together, is by running the cast iron, when in a state of fusion, on the malleable iron; to effect which the malleable part is to be first forged, or otherwise prepared in that form and of that strength which the nature of its intended purpose or appropriation points out as most proper. That part of the malleable iron which is intended to be combined with the cast iron should be rendered rough and uneven byjagging or by perforation, by giving it a dovetailed form, or by any other means, so that the cast iron may firmly adhere thereto, without the liability of becoming loose by the violent action of the carriages. The malleable part must be clean, perfectly dry and warm, when laid in the mould to receive the melted iron, which should be poured in as soon as possible after the mould is ready to receive it, as any damp on the malleable iron will endanger the soundness of the cast iron part.