Mr. Blakey is the only person who ever thought of making use of air as an intermediate body between. steam and water: by which means, the steam is always kept from touching the water, and consequently from being condensed by it. And, on this new principle, he has obtained a patent: so that no one (vary the engine how he will) can make use of air between steam and water, without infringing on the patent, and being subject to the penalties of the law. This engine may be built for a trifling expence, in comparison of the common fire engine now in use: it will seldom need repairs, and will not consume half so much fuel. And as it has no pumps with pistons, it is clear of all their friction: and the effect is equal to the whole strength or compressive force of the steam; which the effect of the common fire engine never is, on account of the great friction of the pistons in their pumps. ARCHIMEDES'S Screw-engine for raising Water. ABCD is a wheel, which is turned round, accord ing to the order of the letters, by the fall of water EF, which need not be more than three feet. The axle G of the wheel is elevated so, as to make an angle of about 44 degrees with the horizon; and on the top of that axle is a wheel H, which turns such another wheel I of the same number of teeth: the axle K of this last wheel being parallel to the axle G of the two former wheels. The axle G is cut into a double-threaded screw exactly resembling the screw on the axis of the fly of a common jack, which must be (what is called) a right-handed screw, like the wood-screws, if the first wheel turns in the direction ABCD; but must be a left-handed screw, if the steam turns the wheel the contrary way. And, which ever way the screw on the axle G be cut, the screw on the axle K must be cut the contrary way; because these axles turn in contrary directions. The screws being thus cut, they must be covered close over with boards like those of a cylindrical cask; and then they will be spiral tubes. Or, they may be made of tubes of stiff leather,and wrapt round the axles in shallow grooves cut therein. The lower end of the axle G turns constantly in the stream that turns the wheel, and the lower ends of the spiral tubes are open into the water. So that, as the wheel and axle are turned round, the water rises in the spiral tubes, and runs out at L, through the holes M, N, as they come about below the axle. These holes (of which there may be any number, as four or six) are in a broad close ring on the top of the axle, into which ring, the water is delivered from the upper open ends of the screw-tubes, and falls into the open box N. The lower end of the axle K turns on a gudgeon, in the water in N; and the spiral tubes in that axle take up the water from N, and deliver it into such another box under the top of K; on which there may be such another wheel as I, to turn a third axle by such a wheel upon it.--And in this manner, water may be raised to any given height, when there is a stream sufficient for that purpose to act on the broad float boards of the first wheel. A quadruple Pump-mill for raising Water. This engine is represented thus: In which ABCD is a wheel, turned by water according to the order of the letters. On the horizontal axis are four small wheels, toothed almost half round: and the parts of their edges. on which there are no teeth are cut down so, as to be even with the bottoms of the teeth where they stand. The teeth of these four wheels take alternately into the teeth of four racks, which hang by two chains over the pullies Q and L; and to the lower ends of these racks there are four iron rods fixed, which go down into the four forcing pumps, S, R, M and N. And, as the wheels turn, the racks and pump-rods are alternately moved up and down. Thus, suppose the wheel G has pulled down the rack I, and drawn up the rack K by the chain: as the last tooth of G just leaves the uppermost tooth of I, the first tooth of H is ready to take into the lowermost tooth of the rack K, and pull it down as far as the teeth go; and then the rack I is pulled upward through the whole space of its teeth, and the wheel G is ready to take bold of it, and pull it down again, and so draw up the other.In the same manner, the wheels E and F work the racks O and P. These four wheels are fixed on the axle of the great wheel in such a manner, with respect to the positions of their teeth, that, whilst they continue turning round, there is never one instant of time in which one or other of the pump-rods is not going down, and forcing the water. So that, in this engine, there is no occasion for having a general air-vessel to all the pumps, to procure a constant stream of water flowing from the upper end of the main pipe. There is an engine of this sort, described in Ramelli's work, but I can truly say, that I never saw it till some time after I had made this model. The said model is not above twice as big as the figure of it, here described. I turn it by a winch fixed on the gudgeon of the axle behind the water wheel; and, when it was newly made, and the pistons and valves in good order, I put tin pipes 15 feet high upon |