PUMP (continued)

The subscribers further certify, that the chain of the new pump was dropped into the well, and afterwards taken up and repaired and set at work again in two minutes and a half; and that they have seen the lower wheel of the said pump taken up to show how readily it might be cleared and refitted for action, after being choaked with sand or gravel.; which they are of opinion may be performed in four or five minutes.

Of late, however, some considerable improvements have been made on the naval chain-pump, by Mr. Cole, under the direction of Capt. Bentinck. The chain of this machine is more simple and mechanical, and much less exposed to damage. It is exactly similar to that of the fire engine, and appears to have been first applied to the pump by Mr. Mylne, to exhaust the water from the caissons at Black-friars bridge. It has thence been transfered to the marine by Capt. Bentinck, after having received some material additions to answer that service. The principal superiority of this pump to the former is, 1. That the chain is more simple and more easily worked, and of course less exposed to injuries by friction. 2. That the chain is secured upon the wheel, and thereby prevented from jerking back when charged with a column of water. 3. That it may be easily taken up and repaired when broken, or choaked with ballast, &c. 4. That it discharges a much greater quantity of water with an inferior number of men.

As we wish to pay all possible attention in this work to every improvement in the marine, we have exhibited in plate VIII. a section of this machine at large,. as fixed in a frigate of war, fig. 2. wherein A is the keel, and V the floor-timbers, and X the kelson, a a a the several links of the chain, b b the valves, C the upper wheels, D the lower wheels, c c the cavities upon the surface of the wheels to receive the valves as they pass round thereon, dd the bolts fixed across the surface of the wheels, to fall in the interval between every two links, to prevent the chain from sliding back.

Plate VIII

The links of the chain, which are no other than two long plates of iron with a hole at each end, and fixed together by two bolts serving as axles, are represented on a larger scale as a a. The valves are two circular plates of iron with a piece of leather between them: these are also exhibited at large by b b.

Upon a trial of this machine with the old chain-pump aboard the Seaford frigate, it appears, in a report signed by rear-admiral Sir John Moore, 12 captains, and 1 1 lieutenants of his majesty's navy, that its effects, when compared with the latter, were as follow.

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