It is often of essential importance to be able to arrest theof a car riage upon a railway with great promptitude ; and the ordinary use for this purpose, have not always been found sufficiently potent for that pm. pose. As a remedy for this inconvenience, Mr. Robert Stevenson, under the same patent, proposes to employ the force of steam acting upon pistons or *nen is small cylinders; so that when it is required to stop the twain, It is only necessary to turn a small cock, which allows the steam to flow instanta neously through a pipe into the cylinder, and by its pressure on the piston, give motion to a system of levers, which cause two brakes or clogs to be forced against the peripheries with great energy, and to arrest the motion of the vehicles very quickly. These clogs or brakes, and their mode of action, are shown in the side elevation on the preceding page. a is the hollow cylinder into which a plunger is fitted, to act by a lever y, and an upright rod f, upon the two brakes gi d, which are suspended by pendulous links a from a centre pin or bolt e fixed to the frame. The brakes are caused to apply to the circumferences of the tires of the wheels K and M, by means of links, which are interposed between the two brakes, and which links, when put down into an angle, as shown in the figure, leave the brakes free of the wheels K and M ; but when, by opening the cock C, the steam from the boiler is admitted through the pipe b b, into the hollow cylinder a, it raises up the plunger therein ; and the latter, by its lever y, and rod f, draws up the links towards a straight line, and then they force the two brakes apart from each other, against the wheels K and M, with an increased force beyond that which the plunger exerts ; that increase of force being in consequence of the leverage at y, and the oblique direction of the links. When the handle of the cock c is turned the other way, it allows the steam to issue through an upright spout, and escape from the cylinders into the open air.
The following letters have reference to the other parts of the engine. At h is the firebox; i the ash-grate ; j is the boiler, cylindrical in shape, through the lower part of the transverse sectional area of which are passed longitudi nally a great number of small brass tubes, proceeding from the furnace chamber, and serving as the hot-air flues, and conduct the same into the "smoke-box" 1, at the other end, whence the resulting gases from the cornball don of the fuel ascend the chimney n ; pis the steam-head ; q a matbay-valva; r another valve, the extremity of the lever of which is held down by the elastic force of a spring steel-yard at a; t is a man hole ; u the working geer ; sr e v the springs; wee the iron brackets that connect the machinery to the wooden frame ; x the fire-door; y, the throttle-cock, provided with a lever and graduated scale. In the end elevation it will be observed that the axes of the running wheels M, like those at 0, are straight ; the form of the axles to the wheels K, are repre sented in the annexed cut, and they are forged with great care from the roughest quality of iron, and are turned and centered as well as the running wheels in the lathe.
Locomotive engines, constructed according to the description of the foregoing, Mr. Stephenson says, have the effect of preventing the boilers being burnt out so soon as usual, by allowing them to be made of greater magnitude and strength ; the additional wheels supporting the extra weight. The bearing springs are used for the extra small wheels, the same as is now done for other wheels in ordinary engines; the six springs used causing all the six wheels to apply and bear fairly on the rails, and ease all jolts and concussions ; the relative weights, or portions of the whole weight of the engine, which is to be borne by each of the six wheels, being regulated by the strength and setting of their respective bearing springs. The main wheels, which are impelled by the power of the engine, are, in all cases, left loaded with as much of the weight of the engine as will cause sufficient adhesion of those wheels to the tails, to avoid 'Uplift thereon. The larger the entire capacity a boiler is, the more metallic heating surface it will contain ; and, oonsequently, Tender unnecessary that extreme heat which is so prejudicial to the metal. And that diminution of the intensity of the combustion, the patentee considers to be advantageous in another point of view ; because the jet of waste steam (which is thrown into the chimney to produce a rapid. draught therein, for exciting the combustion of the fuel) may be greatly diminished in its velocity, which will permit the waste steam to escape from the working cylinders with greater free dom than could be permitted with smaller boilers, wherein a greater heat ann a more rapid generation of steam, are indispensable to furnish the requisite power.
The following cut exhibits another form of Mr. Stephenson's locomotive. engine, such as is now in use, but with the foregoing improvement added thereto. The foremost wheels, at the chimney end of the boiler, are, in this, however, impelled by means of outside cranks and connecting ;oda, as well as the two middle wheels K, which are on the cranked axle; in other respects, the improvement is the same as in the other engine. The brakes, or clogs, are, of course, applicable to this or any other engine, but they are left out in this instance, as being unnecessary to our illustration.
We have, in the previous parts of this article, alluded to the imperfections, which from time to time manifested themselves in the modes adopted for fastening the rails of edge railways to the chairs and sleepers. Owing to the
effects of expansion and contraction, and the violent shocks and strains to which they are subjected, the task of perfecting these parts of the mechanism of rail ways iuu hitherto been found one of difficult accomplishment even to the most experienced and skilful. With the view of remedying these defects, Mr. Robt. Stephenson, jun. obtained letters patent in December 1839, in which he says that the object of his improvement is to provide firm and secure bearings at the bottoms of the notches in the chairs for the rails to rest upon, those bearings being capable of self-adjustment, in order that they may adapt themselves correctly to the under parts of the rails; and the making of adequate provisions for fastening the iron rails securely downwards upon such self-adjusting bearings, as well as for confining the rails laterally within the notches in the chairs, but in such manner that the self-adjusting bearings will not be subject to be deranged, nor the fastenings to be loosened, by the effect of any such slight tilting or inclination of the chairs in the direction of the length of the rails, as may molt from partial or unequal subsidence of the ground beneath the stone blocks or wood sleepers upon which the chairs are fastened, nor by the effects of any such slight elongations and in the length of the rails as they are usually liable to from ordinary changes of temperature. Mr. Stephenson's mode of effecting this, is by the application of a self-adjusting segmental bearing piece into a suitably-formed concavity, made below the level of the bottom of the notch of each chair; the fiat or chord side of the segmental piece being uppermost, and forming the bearing-surface at the bottom of the notch in the chair. Upon that fiat bearing-surface the under side of the iron rail is to rest, so that the bearing-surface will always accommodate itself to the under side of the rail, and form an even contact therewith, in consequence of the circular side of the segmental piece adapting itself to the required position, by turning in its concave cell. The specification of this patent describes the action of these parts, and all the subordinate pieces by which the connexions are formed, with great minuteness. It will however be sufficient, for the generality of our readers, to describe the illustrative drawings that accompany the specification. Fig. 1 is a perspective view, and Fig. 2 a lateral elevation ; i 3 s a mannerse section, and Fig. 4 a horizontal plan of a chair, for supporting and uniting the extremities of the lengths of iron rails for edge-railways. A A is the fiat bottom or base of the chair, which is to be bedded upon the stone block or wooden sleeper, and firmly fastened thereto by spikes driven down through the holes a a. 131i are the cheeks of the notch in the chair, that notch being the parallel space which is left between the cheeks, for the reception of the rails fl c'D d, which may join together with a half lap-joint, as is shown is perspective at Fig. I, and in the plan Irv. 4, the overlapping parts c d being of the same aim, or nearly of the same site. as the other parts of the rails, and those parts are included within the notch of the chair. The bottom of this notch is deeper than is necessary for receiving the rails, and is depressed into a concavity of a receiving the segmental bearing-piece which is shown on the next page, at 4 4 4, in plan, elevation, and perspective : the under edges of the rails rest upon the uppermost flat surface of this bearing piece. The email figures 5 and 6 are cylindrical pins, which are fitted into cylindrical sockets, through each of the cheeks or sides B B; and 8 and 9 are tapering or wedge-like keys, which are inserted through suitable mortices in the cheeks and across the pins 5 and 6, for the purpose of forcing forward those pins, so that their pointed extremities may press obliquely upon the lower Darts of the grooved recesses in the rails, with a bearing-down action, to confine the rails downwards upon the bearing-piece, and laterally in the chair. The cylin drical pins are shown detached, in order to explain the manner in which the pointed extremity applies into the grooved recess in the rails, so as to exert a oearing-down action thereon. Fig. 5 represents perspective views, and Mg. 6 a transverse section of a chair for supporting the iron rails at intermediate dis tances between the extremities or junctions of their several lengths; it has only one cylindrical pin 5, fitted through one of its cheeks B, the opposite cheek IC being a flat vertical surface, against which the flat side of the rail is pressed and held firm, by the keying up of the cylindrical pin 5, so as to confine the rail laterally at the same time, that the oblique action of the point of the cylindrical pin 5, in the grooved recess of the rail, may produce a bearing-down action, which confines the rail down upon the segmental bearing-piece. The chairs are made of cast iron ; the sockets for the cylindrical pins, the mortices for the wedge like keys, and the cells for the segmental bearing-pieces, being formed in the casting, as well as the holes for the holding-down spikes ; the wedge-like cross keys, the cylindrical pins, and the segmental bearing-pieces, are made of wrought iron.