To Laurence Eivers   May 1842

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On Thursday last being a holiday I started at 5 o’clock for Gowran¹ accompanied by a young fellow – a relation of Burchell’s² I arrived in Gowran shortly after 7, called at Lady Dover’s gate³ and found that the person who had the hydraulic ram⁴ in charge had not yet made his appearance – I found the house – rapped him out of bed and was conducted by him to the object of my search – what you told me concerning this engine excited my curiosity and I had half a dozen conjectures formed concerning the affair before I saw it. The moment it met my view I must confess I felt disappointed, it was so utterly unlike any of my preconceived ideas, so I had to crush all my airy conjectures and bring my faculties to bear on the reality. There is something sympathetic between the head and hand when a fellow’s imagination is on the stretch – any one located in my immediate vicinity as I gazed on the hydraulic ram might behold a practical illustration of what I mean. I walked and gazed and stood and gazed and according as my ideas approached the climax of confusion the more frequently my claws and cranium came into contact. One comfort I had amidst the chaos of my brain, the engine keeper promised to explain all to me when I had satisfied myself looking at it. In a short time I requested him to do so, Well, Sir, he placed a hand on each ball, gave two or three ominous ‘hems’ and commenced in the strain of a Connemaran⁵ Cicero⁶ the forensic swell was singularly blended with the Connaught⁷ brogue he hiccupped forth words the pronunciation of which would strangle an ordinary man, in such a manner that if I were to be hanged for it I could not prevent the idea of Corney Delany’s⁸ wrinkles from obtruding itself on my fancy, you may judge from this that the harangue was in no degree calculated to dispel the obscurity of my mind, it required the exercise of all my gravity to keep my risible muscles in proper subjection, the fact of it is when the man had finished I endeavoured very quietly to forget all he had said. By degrees the mysteries of the apparatus began to unfold themselves and half an hour’s investigation gave me a tolerable idea of the principle on which it worked. I shall now send you my solution of the matter: –⁹

L is a metal tube about 4½ inches in diameter one end H communicates with a cistern which is always kept full of water, this end is 10 feet higher than the foot of the tube E – H is a stopper which turns on a hinge, there is a cord attached to it by means of which the end of the tube can be opened and shut at pleasure. B is a spherical valve of highly polished metal, which exactly fits into a round aperture, the only communication between the tube and Ball A – To prevent this spherical valve being dashed aside there is a bridle placed over it within about an inch of its surface. G is a pipe which communicates with the ball nearly on a level with the valve B. Y is a valve adjusted so that it will move up and down at certain times by the action of the water in the tube – when the stopper H is raised the water flows through the tube L and were there no obstacles would continue to flow until it would reach its own level X in the tube G, but it must be remembered that the ball A is full of air, when the water enters the ball through the valve B it prevents all communication between the air in the ball and that outside, hence, according as the water presses upward the air becomes condensed in the top of the ball, a reaction therefore takes place and the water is in its turn pushed back, the valve B descends and the water is impelled with great force through the valve G. It is plain that even if both the valves A and B were dispensed with, the aperture which X fills being stopped and that which B fills being left open, the same would take place to a certain extent, the air would be condensed and the water impelled on the principle of the force pump¹⁰ – when however the water flows through L the valve Y is raised thereby stopping its aperture, the moment the water has attained its utmost height the valve descends thus allowing a quantity of the water to escape which flows into the trough M. This destroys a portion of the upward pressure and allows the air within the ball to exercise an expansive force much superior to that which it would exercise had the valves Y and B been dispensed with.

There is a small cube of brass at a through which an aperture sufficient to admit a small sewing needle runs to the interior of the tube. I put a small pin into it and on my taking it out again a thread of water was ejected with great force.

This engine propels water to the height of 87 feet.

J. Tyndall

RI MS JT 1/11/3526–7

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