The guiding of the carriage is effected by means of levers which turn round the axles of the fore wheels, so as to present the latter in the line of direction required. The axles are supported in a vertical frame which is made to turn horizontally, by means of a guide wheel n, on the top of a spindle o, the lower extremity of which carries a pinion that takes into an internal toothed wheel at p.
Mr. Alexander Gordon states, in his Treatise on Elemental Locomotion, that the principal difficulty Mr. Griffiths had to contend with, was the liability to which the boiler was exposed, of having all the water blown out of the tubes by the force of the steam generated in the lower part, and to the want of a due circulation or ability of the water to return • and he has given the annexed drawing, as exhibiting the construction of the boiler used by Mr. Griffiths, which we insert, as it differs from the specification, and as it is of importance to be acquainted with its defective action. H is the fire-place, J J J the front tubes of each horizontal series, the extremities of which open into vertical tubes' K K, leading into transverse horizontal tubes L L L above, where the steam is designed to be collected for the service of the engines.
An invention of great singularity, but designed to effect a similar object to Mr.
Barry's, inserted a few pages back, was patented in 1822, by the late highly respected and intelligent Mr. David Gordon. Our only information on this matter is derived from the interesting Treatise on Elemental Locomotion, by his son, Mr. Alexander Gordon ; who, it is to be regretted, has omitted to bestow upon his sketch those details which are essential to give it a practicable form : we are therefore obliged to give the proposition in its crude state. The machine consists of a large hollow cylinder, about nine feet in diameter, and five feet long ; having its internal circumference provided with a continuous series of cogged teeth, into which are made to work the cogged running wheels of a locomotive steam engine, of the kind already, described, as will be recognised by the figures. The steam power being corn municated to the wheels of the carriage, causes them to revolve, and to climb up the internal rack of the large cylinder ; the centre of gravity of the engine being thus constantly made to change its position, and to throw its chief weight on the forward side of the axis of the cylinder, the latter Is compelled to roll forward, propelling the vehicle before it, and whatever train may be added to the hinder part. As an example of the utility of this machine, Mr. Alexander Gordon states, that he has lately been informed by Mr. Samuel Moyle, that at a subsequent date, he had used a large drum of this kind with great advantage, for theof heavy over a swamp, in South America. " Having a iron, which was too heavy to carry over otherwise, be rived together into the shape of a large cylinder, and carried over heavy in the inside of It. As the party advanced, this huge machine rolled with
re; Having arrived at their destination, the rivets were cut off, and the plates applied to their intended use. Now it will be obvious that a roller of this kind, so far from deteriorating a road, must materially improve it, and it may not inappropriately a movable rail-road." On the 3d of Fe y, 1824, a patent was granted to Mr.a. Borstal' and John Hill, of Leith, for a locomotive steam carriage ; an account of which was first given in the Bcfaibwy/i Journal of Science, whence we derive the following description.
" A represents the boiler, which is formed of a stout cast-iron or other suit able metal flue, inclosed in a wrought-iron or copper case, as seen in section, where A is the place for fuel, and a a a are parts of the flue, as seen in section, the top being formed into a number of shallow trays or receptacles for contain ing a small quantity of water in a state of being converted into steam, which is admitted from the reservoir by a small pipe. B is the chimney, arising from the centre fine; at D are the two cylinders, one behind the other, which are fitted up with pistons and valves or cocks, in the usual way, for the alternate action of steam above and below the pistons. The boiler being suspended on springs, the steam is conveyed from it to the engines, through the helical pipe e, which has that form given to it to allow the vibration of the boiler, without injury to the steam joints. E is the cistern containing :water for one stage, my 50 to 80 gallons, and is made of strong copper, and air-tight, to sustain a pressure of about 60 pounds to the square inch. At e are one or more air-pumps, which are worked by the beams F E of the engines, and are used to force air into the water vmw.4 that its pressure may drive out, by a convenient pipe, the water into the boiler, at such times and in such quantities as may be required. The two beams are connected at one end with the piston rods, and at the other with the rocking standards H H. At about one-fourth of the length of the beams from the piston rods are the two connecting rode g g, their lower ends being attached to two cranks, formed at angles of 90° from each other on the bind axle, giving, by the action of the steam, a continued rotatory motion to the wheels, without the necessity of a fiy-wheel. The four coach wheels are attached to the axles nearly as in common coaches, except that there is a ratchet wheel formed upon the back part of the nave, with a box wedged into the axle, containing a dog or pall, with a spring on the back of it, for the pur pose of causing the wheels to be impelled when the axle revolves, and at the same time allowing the outer wheel, when the carriage describes a curve, to travel faster than the inner one, and still be ready to receive the impulse of the engine as soon as it comes to a straight course.