or Fish-Pond. See Fish-Ponds.

Pond, is a small pool or lake of water from whence no stream issues. In the Transactions of the Society instituted at London for the Encouragement of Arts, Manufactures, and Commerce, vol. viii., and printed in the year 1790, there is a short account of a machine for draining ponds without disturbing the mud. It was communicated to the society, together with a drawing and model of the machine, by Lieutenant-colonel Darley. The model was made from the description of a machine used by a gentleman near Taunton for many years before, for supplying a cascade in his pleasure-grounds.—The colonel's regiment was then lying at Windsor; and thinking that the invention might be useful to supply the grand cascade at Virginia-water, he made the model, and presented it to the king, who was gracefully pleased to approve of it. In consequence of which, by his majesty's desire, a penstock on that principle was constructed from the model at one of the ponds in the neighbourhood.—The colonel thinks the machine may be useful in the hands of men of science, and applicable to silk, cotton, and other mills, where a steady and uniform velocity of water is wanted; which might be regulated at pleasure, occasioning no current to disturb the mud or fish, as the stream constantly runs from the surface. He says he has often made the experiment by the model in a tub of water.

Of this machine we have given an engraving, taken from the above-mentioned Transactions; and we shall now add the description which accompanies the plate in that work.

In figure 1. A is the pipe, loaded with a rim of lead, Plate of CCCCXIII of such weight as serves to sink it below the surface of the water. B is the discharging pipe, laid through the bank HI. C is the joint on which the pipe A turns its form, which is shown fig. 2. D is the ball or float, which, swimming on the surface of the pond, prevents the pipe A from descending deeper than the length of the chain by which they are connected. E is a chain winding on the windlass F, and serving to raise the tube A above the surface of the water, when the machinery is not in use. G is a flange. III is the bank, represented as if cut through at I, to show the tube B lying within it. K is a post to receive the tube A when lowered, and to prevent its sinking in the mud. In figure 2, A is a cast cylinder, with a plate or cheek, B, which is fastened to the timber of the tube on one side, but not on the other, so the part of the cylinder C turns in the hollow of the wooden tube when it is immersed. A piece of strong fole leather is put inside the brass-plate B, to prevent leaking.

Pond-Weed, in botany. See Potamogeton.