being forced int, the steam-pipe before it descends again through the vertical pipes, I have placed a piece of sheet iron, perforated with small holes, similar to a strainer, in the middle of the steam receiver, all across from end to end, shown by a line across in the drawing, in fig. 7'. I have given to the small pipes in the sections the peculiar serpentine form, in order to enable the steam to rise to the top more rapidly than the water. My generators or boilers are supplied with water by means of one or more revolving cocks, to serve in lieu of the forcing pump, as shown in sheet second, fig. 8', where two cocks are represented, and which number I prefer: n is a vessel, filled with water, of any convenient shape, one side of which vessel is near the furnace, so as to keep the water warm. This vessel is connected with the generator through a tube entering at o, which is shown in section in the drawing. This tube has two revolving cocks, K and L, with a chamber between them as is shown by letter m. The cocks are made to revolve equally by cog wheels gearing into each other; so if cock K is open towards the water reservoir, cock L will be closed towards the tube leading to the generator, the chamber between the cocks will therefore be filled with water through cock K. By that time cock к closes and L opens towards the generator; the water in the chamber will then descend through o into the generator, by its own gravity, and its place be occupied in the chamber by steam from the generator. Cock K opens again towards the chamber, and L is closed towards the generator; the steam in the chamber will be condensed by the water now entering, or escapes into the water reservoir n. This revolution goes on continually. If water be presented by cock L to the generator, and the said generator should be sufficiently full, the water being up to the dotted lines, in such a case the water will not be received, but remains in the chamber until part or the whole is wanted, the cocks constantly revolving. By this arrangement the water can be kept constantly at the desired height. Figs. 1', 2', 3', and 4', elucidate my improvements in the safety apparatus, as applicable to my tubular circulatory steam-generator, or to any other boiler where high or low pressure steam is generated. Fig. 1' shows a longitudinal section of the compound tube: a is the piston rod screwed into the piston b, which piston fits into the cylindrical tube e, screwed or otherwise fixed at its base into the pipe that connects it with the steam receiver or boiler. o is a hole perforated through b to allow the steam to ascend into the hollow space n, above the piston, so that the pressure is equal on both sides with the exception of the piston rod, the diameter of which alone is unbalanced. The piece h, screwed into the upper part of tube e, prevents the steam from ascending higher; another piece, gg, having a hollow space on the top, is screwed into h. Both these pieces have a hole bored in their centre, lengthways, of a diameter equal to the piston rod a, and to allow it to work up and down. The hollow space ii, in the middle of the two pieces g and h, is filled with packing so as to prevent any escape of steam along the piston. The hollow space p, at top, is filled with oil: K is a basin, with water up to the dotted line to keep the upper part cool; the weights with which the safety apparatus are intended to be loaded are placed on the collar m. The hollow tube e has longitudinal openings, as will be perceived by fig. 3', which presents an outside front view of the apparatus, and through these openings the steam escapes whenever the piston brises. These holes may be of an inde finite length and breadth; a jacket F, represented by fig. 2′, which fits over the tube e, and has likewise the same number of longitudinal holes cut through it, slides over the said tube, and, by adjusting this jacket at x, the channel for the escape steam can be made narrower accordingly, as it may be desirable to have the piston rod raised more or less. The hollow vessel L, or a vessel of any other form, slides or is otherwise fixed over the lower part of the apparatus, so as to intercept the steam from incommoding the upper part of it where the rod is loaded. The pipe leads from this hollow vessel L to the steam condenser, or serves for the escape of steam. Fig. 4' presents an outside view of the piston: a is the rod already described: c, c, are packing rings, two on the upper side and two on the lower side. These rings press against the tube e, in order to keep it steam-tight, so that no steam can escape through the longitudinal openings: d, d, are two pieces of metal screwed on at the top and base of the piston to confine the packing rings. Sheet third, fig. 5", exhibits an elevation of my said compound steam-engine, with the aforesaid arrangement of cog-wheels, constituting my said fifth particular. A is the furnace containing the steam generator or boiler: B is the dome on the top of the steam receiver, with the steam-pipe c, and safety apparatus M. D is a cock upon pipe c, through which steam is admitted to the high-pressure engine E. After having acted upon it the said steam passes into the low-pressure engine F, constructed on my principle on a larger scale, so as to allow the steam to expand, and then act upon it as lowpressure: E and F have pinion wheels, of an equal pitch, gearing into a spur wheel G: these wheels determine the power given to each engine by regulating their motion with reference to the power required from each. The steam finds its escape at z into the condenser H: the condensed steam or water runs through pipe 1 by its own gravity towards the two revolving cocks, K, whence it is conveyed back to the feeding pipe in the steam generator. v is an engine constructed upon the plan elucidated by figs. 5 and 6 on sheet first, having two induction and two eduction pipes, which engine serves as a pump in this particular situation. Pipe w sucks the water from the well or river, and carries it into the refrigerator: x receives the water in the refrigerator and carries it downwards: P is the bellows, fanning the fire by means of a band round the axle Q, connected with two pulleys, R and s, or by any other contrivance: o is the valve and lever of the bellows, connected by rod N with the safety apparatus: T and u are pulleys connected by a band to give rotary motion to pump v; but many other contrivances may be used: I is a cock which is only opened before the engine is set to work, in order that the air may be driven out of the pipes and condenser by the steam; the cock may then be shut and the engine set to work: Y is a pipe leading from the safety apparatus to the condenser.' 208. The principle of the high-pressure steam engine, which must next be examined, depends on the power of steam to expand itself very considerably beyond its original bulk, by the addition of a given portion of caloric, thus acquiring a considerable elastic force, which, in this case, is employed to give motion to a piston. One of the greatest advantages attendant on employing the repellent force of steam, as in this form of the engine, consists in an evident saving of the water usually employed in condensation; and this, in locomotive engines, for propelling carriages, is an object of considerable importance. 209. Leupold has furnished a description of a high-pressure engine, in a very valuable work on machines, published in 1724. He ascribes the invention to Papin, and his apparatus consists of two single cylinders placed at some distance from each other, each of which is provided with a piston made to fit air-tight, and connected with a forcing pump. 210. When high-pressure steam is admitted at the bottom of the first cylinder, it is forced upwards, carrying with it the lever of the pump; at the same time that the steam or air is expelled from the other. On this operation being repeated, or rather reversed, the steam is allowed to enter the second cylinder, which is also connected with the boiler, while the steam in the first cylinder is allowed to escape into the air. From this it will be evident that the process of condensation forms no part of the principle of the high-pressure engine; and that the expansion of gunpowder might be made to produce a precisely similar effect. 211. The amazing force to be produced by the expansion of highly elastic vapor did not escape the penetrating notice of that towering genius, which was now directing all its energies towards its improvement. Accordingly, we find, in Mr. Watt's first patent, the following clause, which expressly describes this engine: 'I intend, in many cases, to employ the expansive force of steam to press on the pistons, or whatever inay be used instead of them, in the same manner as the pressure of the atmosphere is now employed in common fire engines. In cases where cold water cannot be had in plenty, the engines may be wrought by the force of steam only, by discharging the steam into the open air after it has done its office.' 212. Messrs. Trevithick and Vivian were the first to employ the high-pressure engine to advantage, as they found it admirably adapted for the purpose of propelling carriages. In this case the steam, after having performed its office, was thrown off into the air; and the condenser, together with the necessary supply of cold water which must have accompanied it, was by this means dispensed with. For the purpose of motion, the high-pressure engine certainly possesses considerable advantages, not the least of which are its cheapness and portability; the danger, however, attendant on the use of steam acting with a force equal to from forty to eighty pounds on the square inch, must inevitably form an insuperable bar to its general introduction to our manufactures. 213. Mr. Woolf's improvements, which we shall presently more fully examine, are of considerable importance, and are founded on the same principle as those of Mr. Watt, namely the power of steam to expand itself, or increase its volume in a very considerable degree, after its passage from the boiler. From a variety of experiments made on this subject, he ascertained that a quantity of steam having the force of five, six, seven, or more pounds on every square inch of the boiler, may be allowed to expand itself to an equal number of times of its own volume, when it would still be equal to the weight of the atmosphere, provided that the cylinder in which the expansion takes place have the same temperature as the steam possessed before it began to increase. 214. The most economical mode of employing this principle consists in the application of two steam cylinders and pistons of unequal size to a high-pressure boiler; the smaller of which should have a communication, both at its top and bottom, with the steam vessel. A communication being also formed between the top of the smaller cylinder and the bottom of the larger cylinder, and vice versâ. When the engine is set to work, steam of a high temperature is admitted from the boiler to act by its elastic force on one side of the smaller piston, while the steam which had last moved it has a cominunication with the larger or condensing cylinder. If both pistons be placed at the top of their respective cylinders, and steam of a pressure equal to forty pounds on the square inch be admitted, the smaller piston will be pressed down; while the steam below it, instead of being allowed to escape into the atmosphere, or pass into the condensing vessel, as in the common engine, is made to enter the larger cylinder above its piston, which will make its downward stroke at the same time as that in the smaller cylinder; and, during this process, the steam which last filled the larger cylinder, will be passing into the condenser to form a vacuum during the downward stroke. 215. To perform the upward stroke it is merely necessary to reverse the action of the respective cylinders; and it will be effected by the pressure of the steam in the top of the small cylinder acting beneath the piston in the great cylinder; thus alternately admitting the steam to the different sides of the smaller piston, while the steam last admitted into the smaller cylinder passes regularly to the different sides of the larger piston, the communication between the condenser and steam boiler being reversed at each stroke. 216. The economical application of this engine may however be best understood by an examination of its effective force when applied to the raising of water. It appears that a double cylinder expansion engine was constructed for Wheal Vor mine in 1815. This has a great cylinde of fifty-three inches in diameter, and nine feet stroke, the small cylinder being about one-fifth of the contents of the great one. The engine works six pumps, which at every stroke raise a load of water of 37,982 pounds weight, seven feet and a half high. This produces a pressure of 141 pounds per square inch on the surface of the great piston, while its average performance may be estimated at 46,000,000 pounds, raised one foot high with each bushel of fuel. 217. The steam or vapor, which is produced by the expansion or ignition of any inflammable body, has frequently been suggested for producing a vacuum, and even furnishing motive force to impel mechanism. Several contrivances of this kind might be noticed, but in the present case our limits will only permit of one exemplification. It is shown in the accompanying figures. 218. The above apparatus was suggested by an ingenious American, and the first part of the machine consists of a metallic or other vessel, or tubes, so constructed that a stream or current of atmospheric air may pass, together with the inflammable vapor, through a considerable space, interrupted by short turns or other impediments, the object of which is to mix and blend the air and the vapor thoroughly with each other, by which union they are rendered highly explosive. 219. Fig. 1, plate VI., consists of an oblong box of tin or other metallic plates, divided horizontally into four compartments, by the partitions a, a, a, which extend alternately from one end of the box to within a short distance of the other end, so that air, entering the lower compartment at b, would be compelled by the partitions to travel the whole length of the box through each compartment, in its ascent to the top. These compartments are divided by the vertical partitions c, c, running the whole length of the box, into half inch spaces, which produces the two-fold advantage of increasing the friction of the particles of vapor and air with each other, and also of preventing violence in the event of any explosion, should such an accident take place within the box. There is a tube d, for the admission of air and the other materials into the lower compartment at b, and another tube e, for the outlet of the explosive mixture from the upper compartment, each covered with a wire-gauze to prevent explosion, which completes the preparing vessel. 220. Fig. 2 is a front view of the apparatus; fig. 3, a section taken transversely; A is a cylinder of brass, copper, or other material, fitted with a plunger or piston B, connected with a crank shaft C, as in a steam-engine. The lower end of the cylinder has a valve D, of at least half its diameter, opening outwards. This valve D may be made very simply by a rim of leather, or other flexible substance, of the same diameter as the opening into the cylinder. This rim of leather is to be tied round the lower end of the cylinder, so as to form a continuation of it. The bottom part of the leather is to be flattened so as to bring its sides together, for four or five inches of its length, and to be kept in that position by slight springs, attached to the edges of the flat part, something like a bow and bow-string. This valve is supported or prevented from being pushed into the cylinder by a plate of metal, of sufficient thickness to bear the pressure of the atmosphere, arched or curved outward, and perforated with as many holes, of one-eighth or one-quarter of an inch diameter, as can conveniently be made in it. The end of the cylinder forms the abutment to the arched plate. 221. A valve E, opening outwards, is fixed in the side of the cylinder at the bottom, for the purpose of admitting air to the interior. The inflammable vapor is passed from the preparing box F (shown detached at fig. 1), through a pipe e e, which extends entirely round the cyÎinder, at the depth of about one-sixth of the stroke of the piston from the top. The cylinder is perforated with small holes, in that part embraced by the pipe e, for the passage of the inflammable vapor to the interior. The neck of this pipe e should be as short as possible, to prevent the vapor condensing before it reaches the cylinder, and should be furnished with a valve ƒ, next the preparing vessel, to cut off the communication between it and the cylinder, while the explosion takes place. A small valve g, next the cylinder, opening outwards, permits the inflammable vapor to be ignited by the flame of a lamp h; these valves being worked by cams i, k, on the revolving crank-shaft, or by any other convenient method. 222. A perforated plate of thin metal is introduced into the cylinder below the piston B, supported and guided by small rods m, m, working sufficiently tight in a stuffing-box in the piston B. This plate ascends and descends with the piston, and is prevented from rising higher than the vapor pipe e, by the upper ends of its rods m, m, striking a stationary part above. In this situation it forms a partition between the explosive mixture and the air in the lower part of the cylinder. A wire gauze should also be placed between the vapor valve f, and inflaming valve g, to prevent explosion, should the former not close in time. It will be seen at fig. 2 that there are two cylinders fitted up in this way. and communicating with the same preparing vessel and crank-shaft. 223. To prepare the explosive mixture, there must be a small quantity of alcohol, either alone or mixed with spirit of turpentine, or any other inflammable material, capable of evaporation, introduced into the lower compartment of the vessel F. A lamp n, or other heat if necessary, is now to be placed under the preparing vessel, for the purpose of raising the temperature, and keeping the materials about blood heat. The flame of a lamp h is also to be stationed at the inflaming valve g. If too much vapor is raised in proportion to the quantity of air, the mixture ceases to be explosive. 224. The piston B, in its ascent, would cause a partial vacuum in the cylinder, but this is prevented by raising the valve E, which supplies the cylinder with air till B reaches the pipe e here the perforated plate, stops, while the piston B continues its motion to the top of the cylinder; the air-valve E is now closed, and the remainder of the cylinder above is supplied |