I HAVE not procured the specification of which the following is an extract. I copy the Monthly Magazine for October, 1811, vol. 32, p. 255.

Mr. Arthur Woolf's Patent, for improvements in the construction and working of Steam Engines, calculated to lessen the consumption of fuel.

THE nature of this invention may be thus described: The working cylinder of the steam engine has no bottom, but is enclosed in another cylinder of such dimensions, that the space between the two, which space is called the receiver, is equal to at least the contents of the working cylinder. The enclosing cylinder has a bottom, and the two cylinders are joined together at the top by flanghes, or any other suitable means, and the lower rim of the working cylinder is about as far distant from the inclosing cylinder as the distance between the sides of the two cylinders. Instead of having a void space for receiving Vol. II. U u

steam below the piston, Mr. W. introduces below it, and into the receiver, such a quantity of oil, &c. as shall, when the piston is at its greatest height, in the working cylinder, fill all the space below it, and fill also the receiver up to the height of a few inches above the lower rim of the working cylinder. If the engine is to be worked by the pressure of the atmosphere, the receiver has a communication with the boiler, which communication being opened, steam is admitted into, and fills the receiver above the oil. If the communication between the receiver and the boiler be now shut off, and a communication be opened from the receiver to the condenser, a vacuum will be formed in the receiver, and then the pressure of the atmosphere, acting upon the piston, will cause it to descend in the working cylinder, pressing the oil, or other fluid body, before it, and causing the fluid to ascend into the receiver; after which the steam is again admitted for the next stroke. If the engine is to be worked by the action of the steam upon the piston, then the working cylinder must, as is usual in steam engines so worked, be furnished with a cover. In this case, instead of the communica tion usual in the engines in common use, for the alternate admission and condensation of steam above and below the piston, the communications in this engine are to the upper part of the working cylinder, and to the upper part of the receivers, the receiver in the engine answering to the space below the piston in other steam engines;,50 that, when the receiver is open to the condenser, and the upper part of the working cylinder open to the boiler, the piston ascends, and vice versâ. To prevent waste of steam, and to keep up the temperature of the oil, the receiver may be enclosed in a steam case, or heat may be applied externally. There should always be some oil above the piston to the height of a few inches, to prevent the passage of the atmospheric air, or of the steam, down

wards, by the side of the piston. To prevent any deviation of the quantity of oil by the working of the engine, means must be provided to restore it to the requisite height, as cocks, valves, &c. regulated by a float or floats upon the surface of the oil, or by means of a pump or pumps worked by the engine itself, or otherwise. By the interposition of the oil, between the piston and the condenser, all waste of steam, by passing the piston, is effectually prevented, and a consequent saving of fuel is effected.

Woolf's method of measuring the elastic force of Steam.

PLATE I. of this number exhibits a measured section of the self-acting and regulating steam valve. A A represents the upper part of the boiler, having its mouth or neck cylindrical, and closed by a well-fitted, but easily moving valve plug, B B C C, which is in fact a metallic tube, open at bottom and closed above, by a cap-piece B B, that by its chamfered rim or projecting part affords the accurate valve-closure when down. The interior parallel lines at D shew the place where a long perforation is made through the side of the cylindrical part of the valve plug from its cap, nearly down to the bottom; which perforation affords a passage for the steam, increasing in magnitude as the elastic force causes the valve to risc. E is the side passage for conveying the steam to its place of operation. F is the rod or tail of the valve passing through a stuffing box above, and attached by a chain to the scctor G, and by its means moving the lever that carries the ball H,

The above constitutes the whole of this simple and effectual contrivance, and its mode of operation scarcely needs to be described. As the steam becomes stronger it raises the valve, and escapes through D, and raises the weight H higher the more the pressure within execeds that of the working steam in the upper space F E,

On Mr. Arthur Woolf's improved apparatus, applicable to Steam Engines and other purposes of art and manufacture: including a description of two boilers now erecting at Messrs. Meux's Brewery.

MR. WOOLF'S improved apparatus consists, First, of two or more cylindrical vessels properly connected together, and so disposed as to constitute a strong and fit receptacle for water, or any other fluid intended to be converted into steam, whether at the usual heats or at temperatures and under pressures uncommonly high; and also to present an extensive portion of convex surface to the current of flame, or heated air or vapour from a fire: Secondly, of other cylindrical receptacles placed above these cylinders, and properly connected with them, for the purpose of containing water and steam, and for the reception, transmission, and useful application of the steam generated from the heated water or other fluid: and, Thirdly, of a furnace so adapted to the cylindrical parts just mentioned, as to cause the greater part of the surface of all and each of them, or as much of the said surface as may be convenient or desirable, to receive the direct action of the fire, or heated air and vapour.

That our readers may be able fully to comprehend the way in which Mr. Woolf constructs his apparatus, we shall present some plans and views, with such a description as will, we hope, convey a pretty correct idea of their

nature.

Fig. 1. (Plate II.) represents one of his boilers in its most simple form. It consists of eight tubes marked a, made of cast iron or any other fit metal, which are each connected with the cylinder A placed above them, as shown in the side view fig. 2, in which the same letters refer to the same parts as in fig. 1. In fig. 2. is also shown the way in which the fire is made to act. The fuel rests on the bars at B, and the flame, heated air and vapour, being reverberated from the part above the two

first smaller cylinders, goes under the third, over the fourth, under the fifth, over the sixth, under the seventh, and partly over partly under the eighth small cylindric tube. The direction of the flame, till it reaches the last-mentioned tube, is shown by the dotted curved line and arrows. When it has reached that end of the furnace it is carried by the flue C to the other side of a wall, built under and in the direction of the main cylinder A, and then returns under the seventh smaller cylinder, over the sixth, under the fifth, over the fourth, under the third, over the second, and partly over partly under the first; when it passes into the chimney. The wall before mentioned, which divides the furnace longitudinally, answers the double purpose of lengthening the course which the flame and heated air have to traverse, giving off heat to the boiler in their passage, and of securing from being destroyed by the fire the flanges or other joinings employed to unite the smaller tubes to the main cylinder. The ends of the smaller cylindric tubes rest on the brick-work which forms the sides of the furnace, and one end of each of them is furnished with a cover, secured in its place by screws or any other adequate means, but which can be taken off at pleasure, to allow the tubes to be freed, from time to time, from any incrustation or sediment which may be deposited in them. To any convenient part of the main cylinder A, a tube is affixed, to convey the steam to the steam-engine, or to any vessel intended to be heated by means of steam.

When very high temperatures are not to be employed, the kind of boiler just described is found to answer very well; but where the utmost force of the fire is desirable, Mr. Woolf, for a reason which shall be afterwards mentioned, combines the parts in a manner somewhat different, though the same in principle. Having been permitted to inspect two boilers of this kind which he is now