in the boiler at the time of setting out; travelling at the rate of five miles an hour."

As there is no account given of the inclination of the road, we cannot judge of the real performance of the engine. It had, it appears, only one cylinder, and, from what we can learn, did not materially differ, in construction, from that previously described, except in the form of the carriage.

The great obstacle, to the introduction of steam carriages upon railroads, at that time, was the supposed want of hold, or adhesion, of the wheels upon the rails, to effect the locomotion of the engine. Messrs. Trevithick and Vivian, in their patent, recommended making the external periphery of the wheels rough or uneven, by using projecting heads of nails, bolts, or cross-grooves; or, in case of a hard pull, to cause a lever, bolt, or claw, to project through the rim of one, or both of the wheels, driven by the engine, to take hold of the ground. But it will appear obvious to any one, that this mode of remedying one defect, would be the means of producing another; for any projections, would not only cause considerable resistance to the progressive motion of the engine, but would also tend to injure the rails of the road.

Art. 2.-Blenkinsop's Engine.

To obviate these defects, Mr. Blenkinsop, of Middleton colliery, near Leeds, in 1811, obtained a patent for the application of a rack, or toothed rail, stretched along the whole distance to be travelled; into which cog-wheels, turned by the engine, worked, and thus produced a progressive motion, in the carriages.

The annexed drawing, No. 1, will convey a pretty correct idea of the mode of action, of this kind of engine. R R, represents a portion of the rails, constituting the railroad, on the side of which were cast the semicircular protuberances, or projections, 1 1 1, &c. These semicircular teeth projected, from the side of the rail, two or three inches, thus forming a longitudinal toothed rack, which was extended the whole length of the road. a a, are the cylinders, placed within the boiler. The action was communicated, by the pistons, to the connecting rods, bb, which transferred the motion to the cranks, c c, turning axles, attached to the inside of the frame of the carriage. Upon the axles, on which these cranks were fixed, were also fixed the pinion-wheels, dd, which were turned round by the cranks; these two pinion-wheels communicated with a larger cog-wheel, e, in such a manner, that both contributed in producing a rotatory motion in it. The action of this cog-wheel, e, extended to the outside of the frame of the engine, and upon the end of it was affixed the larger toothed

wheel, f, which was thus turned round by the large cog-wheel, and, consequently, by the action of the engine; and the teeth of this cogwheel, being made to correspond with, and lay hold of, the toothed projections, on the side of the rail, a progressive motion of the carriage was thereby effected. The steam, after performing its office, in the cylinder, was allowed to escape into the atmosphere, through the pipe, s. The boiler was cylindrical, and heated by a circular tube passing through it, terminated, at one end, by the chimney. The toothed or rack rail, was only laid on one side of the road, the other being common rails. The cog-wheels were varied in size, according to the different velocity with which it was required to travel.

By the use of this rack-rail, Mr. Blenkinsop's engine was enabled to ascend acclivities, which Mr. Trevithick's engine, from the want of adhesion, could not surmount. Mr. Blenkinsop, soon after the date of his patent, erected some of those engines, and employed them upon the Middleton colliery railroad, in conveying coals to Leeds, where they were used for several years; but it having been since proved, that the adhesion of the wheels was sufficient, to accomplish the progressive motion, the rack-rail has been abandoned.

The engine, erected by Mr. Trevithick, had one cylinder only, with a fly-wheel, to secure a rotatory motion in the crank, at the end of each stroke. An engine of this kind was sent to the North, for Mr. Blackett, of Wylam, but was, for some cause, or other, never used upon his railroad, but was applied to blow a cupola, at an iron foundry, in Newcastle. Mr. Blackett, however, had, in 1813, an engine of this kind made, and set upon his railroad, which worked by the adhesion of its wheels upon the rails. Still, the supposed want of adhesion formed the great obstacle to their introduction, and the attention of

engineers was directed, to obtain a substitute for this supposed defect.

Art. 3.-Chapman's Engine.

The

In December, 1812, Messrs. William and Edward Chapman obtained a patent, for a mode of effecting the locomotion of the engine, by means of a chain, stretched along the middle of the railroad, the whole length, properly secured at each end, and at proper intervals. This chain was made to wind partly round, or to pass over, a grooved wheel, turned by the engine, of such a form, that the wheel could not turn round, without causing the chain to pass along with it. When this wheel was turned round by the engine, as the chain was fastened firmly at the end, and could not be drawn forward by the wheel, the carriage was, therefore, moved forward, in the line of the chain and road. carriages, containing the goods, were attached to the engine carriage, and thus conveyed along the railway. At intervals of every eight, or ten, yards, the chain was secured, by means of upright forks, into which it fell, when left at liberty; this was for the purpose of taking off the strain, from the chain, when more than one engine was travelling by it. The chain was prevented slipping, when the grooved wheel was turned round, by friction rollers pressing it into the groove. Mr. Chapman had one of his engines tried upon the Heaton railroad, near Newcastle, but it was soon abandoned; the great friction of the chain, and also its liability to get out of order, operated considerably against it.

Art. 4.-Brunton's Engine.

In 1813, Mr. Brunton, of Butterley iron works, also obtained a patent for a mode of accomplishing the loco

motion of the engine, without the aid of the adhesion of the wheels upon the rail, of which, as it displays great ingenuity, we have given a drawing.

No. 2, is a side view of the engine. The boiler was nearly similar to that of Mr. Blenkinsop, cylindrical, with a tube, passing through it, to contain the fuel. The cylinder, A, was placed on one side of the boiler; the piston rod projected out behind, horizontally, and was attached to the leg, ab, at a, and to the reciprocating lever, a c, which is fixed at c. At the lower extremity of the leg, a b, feet were attached, by a joint, at b. These feet, to lay a firm hold upon the ground, were furnished with short prongs, which prevented them from slipping, and were sufficiently broad, to prevent their injuring the road.

On inspecting the drawing, it will be seen, that when the pistonrod is projected out from the cylinder, it will tend to push the end of the lever, or leg, a, from it, in a direction parallel to the line of the cylinder; but as the leg, ab, is prevented from moving back