ON THE VARIOUS KINDS OF RAIL ROADS. In the preceding parts of this work numerous detached notices of particular railways have been inserted, but a connected view (coup d'œil, as it were) of the several distinctive kinds has been hitherto omitted. To supply such a deficiency in this metallic age, when people think of little else but iron, steam, and the vote by ballot, is the object of the annexed summary; which is compiled from the works of Tredgold, Palmer, Wood, and Brewster. The are three distinct kind of rail-roads, namely, edge, tram, suspension, and each of these have some varieties. The oldest and most extensively adopted consisted in laying rails of wood or iron, the carriages being guided therein by flanges on the peripheries of the wheels, and these were called edge-rails, to distinguish them from the tram-plates. which came into use afterwards. EDGE RAIL-WAYS Were first made of wood in the neighbourhood of Newcastle, for the purpose of conveying coals to the side of the river Tyne; these were next covered with plates of wrought iron in the parts most liable to wear.. Cast iron was subsequently introduced there, as well as in many other parts of the country, and now wrought iron is being very generally substituted for the cast. In the annexed cuts, figs. 1, 2, and 3, are a side view, plan, and transverse section of a cast iron edge-rail, of the form which has been adopted in the best railways on the banks of the Tyne and the Wear. The waggons run upon the rounded edge of the rail, which is smooth, and laid as evenly as possible. The length of these rails is usually 3 feet, with a depth of 4 inches in the middle, and breadth of the top 2 inches. The ends of the rails rest on a piece of cast iron called a chair (as shewn at fig. 4) and the chairs are fixed to blocks of stone called sleepers, (being a ways in bed), these have a broad base, and weigh about 2 cwt. each. They are firmly bedded in the ground, and are adjusted to the plane required for the road, before the chairs are connected to them. The goodness of the road depends much on the fixing of the sleepers in a sound and firm manner. In fig. I the side view of the rail c is shown supported at the extremities A B, by cast iron chairs EE, which rest on the stone sleepers D D. In fig. 2, the plan, is shown the scarf joints where the ends of the rails meet in the iron chairs E E. Fig. 3 represents the cross section of the middle of the rail as at c in fig. 1, which is the middle of its length. Fig. 4 is a cross section at B, through the joint chair and supporting block. Rails made entirely of malleable iron were first employed by Mr. George Grieve, at Sir John Hope's collieries near Edinburgh; these were formed of rectangular bars, which obviously present too small a surface for the wheels to run upon, or otherwise re1ST NOVEMBER, 1830. VOL. V.-No. 88. BB quire more materials than it would be consistent with economy to employ; and to obviate this difficulty, a patent was obtained by Mr. John Birkinshaw, of Bedlington Iron Works, Durham, for an improved form for the hars to be used as rails. It consists in giving the bar the form of a triangular prism, or such variation of that form as is best adapted for that purpose. Fig. 5, (in the preceding engraving) represents this section recommended by Mr. Birkinshaw, and he proposes that the rails should be eighteen feet in length. Fig. 6 represents another form, which is evidently better. His suggestion, respecting welding the joinings, would rather be injurious than useful, owing to the expansion in length by increase of temperature. The chief advantage of wrought iron rails is that of reducing the number of joints; and the difficulty of making the rails perfectly even at the joints has contributed much towards their introduction. Edge rails are most adapted for permanent works. They are of such a nature, that ordinary carriages cannot be employed upon them; but on any railway where such carriages can be used, they must do more injury to the surfaces of the rails, than will be equivalent to the advantage of suffering them to go there. TRAM-WAYS, OR TRAM-ROADS, Differ from the preceding kind, in having the guiding flanges upon the rails, instead upon the wheels of the carriages; it gives the advantage of employing carriages that can be used where there are not rails laid down. They are called tram-roads, from their being first used for drawing trams upon. The tram-rail is exceedingly convenient for temporary uses, and in its ordinary form (as represented at fig. 8, in the subjoined engraving), it is much used in quarries, in mines, in forming new roads, and in digging canals, in conveying large stones for buildings, and other purposes. Tram-rails are of a very weak form, considering the quantity of iron in them, and in some works it had been found necessary to strengthen them, by adding a rib on the under side. Fig. 12, shows half a tram-rail of this kind in perspective, A being the guide; B the bed of the rail, in which the wheels run; c the rib on the underside to strengthen it. The rails used for repairing the Surrey tram-roads were of this form, and it certainly renders them very strong. The third kind of railways mentioned are those on the principle of suspension, of which that invented by Mr. H. R. Palmer, is we believe, the earliest and the best. (See Register of Arts vol. 1, page 96 and 113—vol 2, page 72, 150-vol. 3, page 140;—also Fisher's railway, vol. 3, page 268.-James's, vol. 4, page 6, &c. As tram-rails are applied with so much benefit in forming temporary ways, the most convenient and ready mode of putting them down is an object of some importance. The common method is to fix them with large nails or spikes upon cross sleepers of wood. The chief inconvenience of this plan is the difficulty of driving and drawing the nails when they have to be changed. For permanent roads, the rails are usually fixed by spikes driven into wooden plugs, previously inserted in the blocks of stone for supporting the rails, as shown in fig. 8; where в shows the tram-plate (in section), with one of the running wheels of the carriage thereon; c the stone sleeper, in which is inserted the wooden plug to receive the nail: A is part of the gravelled horsepath or road. An attempt to improve the method of putting down tramplates, by Mr. Le Caan, affords great facility in taking up or putting down the rails; they are contrived so as to fix one another, without the aid of nailing. Fig. 10, represents a longitudinal section of two of these plates, placed on a stone sleeper d, and fig. 9 is a plan of the two plates. The plates are joined by a dovetailed notch and tenon, and an oblique plug is cast on each plate, which is let into the stone sleeper. But, for the advantage of taking up the plates, to repair any defect, there are plates at every thirty yards, with perpendicular plugs; such plates are called stop plates. The diameter of the plug near the shoulder is one inch and three quarters, at the point one inch, its length is two inches and a half, and its obliquity, shewn in fig. 10, about eight degrees. A small groove in the whole length of the exterior of such plug, is made to allow the water in the hole to expand in freezing, and it also serves to admit a wire to draw a plug out by. The holes for the plugs should be cut to the depth of three inches, by a standard gauge of cast iron, and countersunk, so as to allow the end of the plate to bed firmly on the block which supports it. Fig. 11, is one of the ends of a tram plate, in which H shews the flange or upright edge; i the flat part or sole, in which the wheels of the waggon run; D one of the plugs, and K a projection behind, to render the plates firmer upon the blocks. The usual length of one plate is three feet; the flanch H is one and a half inch high; the sole or bed, three and a half or four inches broad, and three fourths of an inch thick; but these dimensions are varied according to circumstances: the most approved weight has been forty-two pounds for each plate. The ends from which the plugs project, under which the tenons and notches are made, should be a quarter of an inch thicker than the other parts of the plate. In this method the wheels of the waggons cannot be obstructed by the heads of the nails rising above the surface, and the blocks are not disturbed by fixing the plates; and when repairs are necessary, the plates must be formed for the purpose. When tram-plates are fixed by spikes to stone sleepers, there is some difficulty in keeping the joint even and in its place, but it seems to be successfully obviated by using a saddle piece to receive the ends of the nails at the joints, an improvement which was introduced by Mr. Wilson on the Troon tram-road. AN ACCOUNT OF AN EXTRAORDINARY ADHESION OF TO THE EDITOR OF THE JOURNAL OF THE FRANKLIN INSTITUTE. SIR,-The late awful explosion of the steam boat, Helen M'Gregor, has brought to my recollection an accident that occurred last summer under my own eye. Believing it may serve the cause of humanity, I think it my duty to make public the fact; it is this: : Last summer I was engineer on board the steam boat, Legislator, belonging to Hudson standing on the forward deck, I noticed that the engine was working faster than common, and not seeing any steam flow as usual from the safety valve, I started for the fire-room, where I met the fireman then on duty; he told me that he had on twenty-one inches of steam, and that the rod in the steam gauge was up against the boiler deck. As the safety valve was loaded to carry only sixteen inches, I became alarmed, and went to the fire-room and took hold of a cord that ran over a pulley, and was attached to the lever of the safety valve, and attempted to raise the valve but could not; I was still more alarmed, and went on the top of the boiler, where the safety valve was, and found all right there, that is, there was no extra weight on the valve; I then slided the weight in to the length of the lever up to the fulcrum, where the weight was merely nominal, still the valve did not rise; I became confounded; I took hold of the lever and lifted on it pretty stoutly, and continued lifting for some seconds, when all of a sudden, with an explosion like that of the report of a small field-piece, the valve opened, and the steam rushed out violently; it continued to do for some length of time before the steam got down to the usual pressure, the engine being at work all the time. There was no water on the valve, nor any visible obstruction to its rising of its own accord after the steam got beyond the pressure of sixteen inches, which it had invariably done before. Now, Sir, must not this obstruction to the valve rising have been caused by an adhesion that took place between the valve and the valve seat, both of the same metal? I think it certainly must have been caused by this adhesion of the metal only. I have had an experience of twelve years as an engineer, and never knew the like occurrence before. For many reasons I have not placed full reliance in the mercurial steam gauge, but have always had entire confidence in the correctness and safety of the safety valve; but in this case I was deceived, and perhaps in a few moments more an explosion might have taken place, for I have no doubt that if the small rod in the steam gauge had had a free passage through the boiler deck, it would have denoted thirty instead of sixteen inches. It is usual on board steam boats to have the steam gange so graduated as to show as many inches of steam as the engine will take, and to have the safety valve loaded so as to agree with the steam gauge, believing that when the steam gauge indicated sixteen inches |