"Fig. 10 is the bird's-eye view of a rotary engine, as wrought with a cock or portion of a circle, whereby a similar effect is produced as in Fig. 1, by or with a portion of circles: in these figures, 8, 11, the lids of the cylinders are removed, and a part of the flanges where the circles or irregular cocks are used is broken off, to render the working parts conspicuous. A, the outer or fixed cylinder. B, inner or revolving cylinder. CC, the pallet, cock, or portion of a circle, fitted accurately into the circlé it prescribes; with a spindle working through the top of the cylinder. D, the groove, into or against which the part coming into contact with the revolving cylinder is secured with a piece of hardened metal, in order that the constant friction of the revolving cylinder shall not injure the pallet or cock. E the passage to the boiler. F the passage to the condenser. G the pallet secured to the working cylinder. In this figure two portions of circles and cocks are introduced, for the purpose of showing clearly their situations in different places, the same as in Fig. 10.

"Fig. 11 exhibits the bird's-eye view of a rotatory engine, as wrought by a cock or cocks, which regulate the steam instead of valves, and also act as the principal cock or pallet in the said engine. A the outer fixed cylinder. B the inner revolving cylinder, with a fixed pallet. CC the cocks, which are wrought from the external part of the engine, by a spindle passing through the top. D a piece of hard metal, introduced into the said cock, to resist the friction of the revolving cylinder, as explained in Fig. 10. E, steam passage. F, passage to the condenser."*

The first of Mr. Wilcox's plans (1 and 2) is, as far as we know, perfectly original. Its great complexity has been, no doubt, a great cause of its abandonment; if, indeed, it was ever tried. The number of racks, pinions, gates, pallets, joints, grooves, slides, and stuffing boxes, must instantly impress the mind of every one with an idea of its great inferiority to the most complex reciprocating engine.

The second scheme, (4 and 5) it will be perceived, resembles in its general principle one of Messrs. Bramah and Dickenson's engines, a description and plan of which will be found at page 70 of this work The objections, therefore, which have been made against that plan; will apply equally to Mr. Wilcox's.

In the third plan (Fig. 8) we apprehend that a great waste of steam would arise from the difficulty of making the pallets, D, unite sufficiently close at the joints; besides that the complexity would be nearly as great as the first plan.

The fourth and fifth plans (10 and 11) resemble that of Mr. Flint's so nearly that we doubt not they failed from the same cause.

In the year 1807, Mr. Henry Maudslay, of London, obtained a patent for a Portable Engine, in which he introduced several ingenious improvements on the valves and working parts of steam engines, which tended not only to reduce the friction, but altogether to render them tighter and more compact. The accompanying figure will enable our readers to understand what these improvements were.

* Specification of Patent.

A represents a frame of thin cast iron, for the purpose of fixing the cylinder. B B are two cold water cisterns, of merely sufficient size to admit of easy access to the pumps within them; they communicate with each other by a pipe a. C is the cylinder surrounded by a casing (6) of copper or other material. The space between the cylinder and casing is filled with wool or some other imperfect conductor of heat; D is the piston rod joined to smaller rods carried down on each side of the cylinder to E, and having an opening or division so as to avoid interfering with the main shaft. These rods are at their lower ends fixed to a wheel F, with a fluted rim: from the centre of which a connecting rod, G, is carried to the end of the crank. The wheel F runs between two guides, cc, so as to preserve the rectilineal motion of the rods E, and the piston rod D. H is the crank, a three-throwed one. J a cross beam for working the pumps

POM; its motion is procured by having a fork underneath it, which embraces one of the cranks H, on which is a roller for reducing friction. By this means the fork, and consequently the beam and pump rods, is reciprocated by the revolution of the shaft. K K is the fly wheel; L is the condenser, containing the air pump M; N is the hot water cistern, and O the hot water pump; P the cold water pump; Q the injection cock; R the steam pipe from the boiler to the cylinder; S the eduction pipe. The steam is admitted into the cylinder by a four-way cock, which differs from that generally used by its being considerably more taper, which effectually prevents it from jamming by unequal expansion or contraction, an evil to which the common cock is liable.

There are few machines which display more ingenuity, either by skilful arrangement or neatness, than this; and, as it regards its utility, it need only be said that long continued trials have fully established the great excellence of Mr. Maudslay's engine. We do not pass over this machine, therefore, with so short a description on account of any doubt respecting its merits; for were the length of our remarks to be governed by our opinion of the utility of any machine, they would in this instance extend over several pages. But however beautiful may be the arrangement of Mr. Maudslay's engines, this is not their sole merit; for Mr. M. has, by superior workmanship, and most careful attention to the selection of good materials, obtained the reputation of being one of the best manufacturers of steam engines in the world.

CHAPTER VI.

CONTENTS.-MEAD'S ROTATIVE ENGINE.-CLEGG'S STEAM WHEEL.-CHAPMAN'S STEAM WHEEL.-WITTY'S ROTATIVE FROM RECTILINEAL MOTION.-ONION'S STEAM WHEEL.-BLENKINSOP'S LOCO-MOTIVE ENGINE.-BRUNTON'S LOCOMOTIVE ENGine, or mecHANICAL TRAVELLER.-DODD AND STEPHENSON'S LOCO-MOTIVe engine.-TREVITHICK'S ROTATIVE ENGINE AND IMPROVED STEAM BOAT. TURNER'S ROTATIVE ENGINE.-LOSH AND STEPHENSON'S IMPROVED LOCO-MOTIVE ENGINE.-ROUTLEDGE'S ROTATIVE ENGINE.MALAM'S IMPROVEMENTS.—SIR W. CONGREVE'S STFAM WHEEL.-WRIGHT'S ENGINE PONTIFEX'S IMPROVEMENTS -RIDER'S ROTATORY ENGINE.MASTERMAN'S STEAM WHEEL.

We stated in our remarks on Hornblower's Steam Wheel, (described at page 77) that it had been claimed as an original invention many years after Mr. Hornblower obtained a patent for it, we alluded. to the patent of Mr. T. Mead, of Hull, dated 1808, the specification of which describes a machine resembling in principle, though of a somewhat different form, to this engine of Hornblower's.

"A and B, Fig. 1, are two circular plates or shells of metal, similar in their construction, having their insides turned, or otherwise made very true and correct; A has its inside uppermost, and B its outside uppermost. Each of these circular plates or shells have a, flange and semicircular cavity formed for the reception of the pistons which are afterwards described, and a recess or hollow part formed round its centre for a small circular plate to turn in. Near to the edge of each recess is a small groove running quite round it; in the bottom of each groove is placed a metallic ring, OO, capable of

17:

arm;

being adjusted by screws on the outside of each shell. At its centre is a hollow pipe or oss for the reception of the spindles, F and G. The plate A has also two holes, a a, Fig. 3, to which pipes are fitted, one to convey steam into the shells, the other to conduct it from them into a condenser, or wherever it may be required. CC two pistons with grooves round them to admit of a packing or wadding. D and E two circular plates to which the pistons are connected or made fast. F and G two shafts or spindles; the spindle G is made hollow to receive the spindle F, which passes through it. H and I two arms made fast to the two spindles; each arm, near its extremity, carries a wheel K and J, which are generally termed friction wheels. La fly or a regulating wheel, fixed to one end of a shaft or moveable axis, having in its side opposite to its axis a groove running across its diameter for the reception of the friction wheels J and K, which wheels, when the pistons are put in motion, work in it, and give motion to the fly wheel and other machinery which may be connected with it. RR the hollow plates or bosses for the spindles to work in; SS flanges by which the shells are fastened together. Fig. 2 is a front view of one of the pistons, with its circular plate, arm and friction wheel; J the friction wheel; H the Da circular plate, and C the piston. VVV grooves for the reception of the packing or wadding, which is to be made fast therein. When the engine is to be put together, the arms are taken off from the spindles; the spindle F is then to be inserted in the hollow spindle G, which, with their respective pistons, are placed in one of the shells, and the one shell placed over the other; the shells are then fastened together with screws or otherwise, so as just to admit the pistons with their respective plates and spindles to turn round in their channels nearly steam-tight; the arms may then be made fast on the spindles, and the engine erected. Place the direction of its axis in an horizontal or lateral direction, parallel with the direction of the axis of the fly, but nearly as much out of that line as the length of one of the arms, H and I, taken from the centre of the spindle to the centre of its friction wheel, and at such a distance from the fly as to admit of the friction wheels moving freely in the groove on its face. By so doing the axis of the engine will be placed eccentric with the axis of the fly. The engine may be fixed in an iron or wood frame, and the fly supported in the same or a separate frame, in the position before pointed out. If the fly is then turned half way round upon its axis, one of the friction wheels will remain locked or held fast in the groove near its centre, and the piston with which it is connected remain nearly stationary in the steam chamber, between the holes a a, while the other friction wheel, with its arm, spindle, small circular plate and piston, make nearly one complete revolution, round their common centre of motion, or the centre of the engine. If the motion of the fly continue till it has made one complete revolution round its own axis, the friction wheel which was locked or held fast in the groove near its centre, will move off in the groove towards the circumference of the fly, and with its arm, spindle, small circular plate, and piston, make nearly one complete revolution round their common centre of motion, or the centre of the engine,