Imatges de pàgina

of iron or wooden pipes extending from 18 to 30, or 40 feet in length, according to their diameter, to conduct the water away: these pipes are laid in a sloping direction, so as to reach the greatest depth D at which the water can run off, which may be from one to six, or eight feet below the head A. The water would naturally run to waste from the end E of these pipes; but that is closed by a blank or solid faunch, and it is only permitted to escape through a round hole in the centre of the horizontal flaunch F, from whence it will run in an uninterrupted stream. This hole is, however, equipped with a valve within it, as at f, and this valve is so adjusted as to sink by its own weight in the water, while that water is motionless or moving slowly. Now if we suppose the pipe B C D to be supplied with water from A, that water will at first pass round the valve, and discharges itself at F; but as soon as it has acquired a small additional force by moving, it will be more than equivalent to the weight of the valve f, and will lift it, by which the passage of the water becomes instantly stopped, and an effort will be made to burst the pipe D; this is prevented by the second orifice over the letter D, communicating with the chamber G and air-vessel H, from whence there is an immediate communication by the pipe II I, with the elevated situations to which the water is to be thrown. As the effect of the blow which the water makes is instantaneous, it becomes necessary to place a second valve v between the air vessel and the chamber G, but below the pipe I I, so that any water which is thrown into H by the effort may be confined there, and acted upon by the condensed air, instead of permiting it to return and equalize itself in the pipes C, D. The blow which the water makes is so sudden and violent, as to produce an expansion in the pipe D, which is as suddenly succeeded by a recontraction and trifling vacuum in D, by the tendency of the water to return up C when stopped; the effect of this is to bring down the valve f, by which a free passage is once more opened for the water, which again flows and shuts f as before, to produce another blow or pulsation, by which a second quantity of water is thrown up I I. Each repetition of this operation affords a fresh supply of water.



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It will be evident that the valve f, as well as v, will require some adjustment as to weight. This is effected by making these valves of hollow brass balls, having a hole on one side, by which some shot or small pieces of metal can be introduced to adjust the weight. The hole is afterwards stopped by a screw which projects and forms a shank or tail to guide the valve. The screw over v is likewise to adjust the height to which that valve should ris, and to prevent its breaking away and getting into the air vessel, which it otherwise might do from the violence of the blow.

It has been found, that after using the water ram for a short time as it was formerly constructed, the air in H became absorbed and entirely disappeared, and by its ceasing to act as an air vessel, the water would not proceed to any great height up I I. This is obviated in the present case by the chamber G placed between the air vessel and the pipe D. From the form of this chamber any air which enters it becomes confined in the recesses K K, and not only equalizes the action on the vale o, but makes the whole motion less instantaneous. KK becomes supplied with air in small machines by the falling of the valve f, which brings a small quantity of air down with it. In larger ones it will be necessary to apply a small shifting valve, or spring valve opening inwards to some part of the outside of G, when the air as it enters will rise to the top

of KK, and as it accumulates will at length pass through v into H and keep it supplied with air. This latter contrivance I believe originated with Mr. Dobson, of Mortimer-street, Cavendish-square, who has paid considerable attention to the improvement of this engine, and proposes erecting them for the public.

In the rams which I have seen, the tubes B, C, D, have been from 12 inch to 4 inches diameter, and the ascending pipes II, one inch, or rather less. I have seen the valve f make from 50 to 70 pulsations in a minute, and I should think discharging near half a pint of water at each pulsation, at the height of 30 feet with a six feet head. I am, however, told, that a machine has been made which furnishes an hundred

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hogsheads of water in 24 hours, to the height of 134 feet perpendicular, with a fall of four feet and an half.

I am not aware that the best proportion of parts has yet been ascertained, or the quantity of loss compared with the quantity delivered up I I, which must in a great measure depend upon the heights of the respective heads, and the size and length of B C compared with the perpendicular fall from A to D. I intend entering into an examination of these points, and if you should think the result of my enquiries worth inserting in a future number of your Journal, they shall be very much at your service.

I remain, dear sir,
Your's very truly,

JOHN MILLINGTON. Upper Mall, Hammersmith,

10th June, 1816.

Some Remarks on the Arts of India, with miscellaneous Obser

vations on various Subjects. By H. Scott, M. D.

[From the Journal of Science and the Arts, No. II, for 1816.]

DURING a long residence in India, I communicated to Sir Joseph Banks some observations that I had made on the arts of that country, and I intermixed occasionally some speculations of my own. He kindly sent replies to my letters, and took a very active part in endeavouring to promote several of their objects.

He lately told me that a part of my communications had not been without effect, while others had made no progress. Men slowly alter their habits, and receive, perhaps wisely, whatever is new with reluctance and distrust.

Among the new objects to which he referred as having done some good, he mentioned to me the Wootz, or Indian steel. This steel is now acknowledged to be of an excellent quality,

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