o, p, two cocks, each of which passes through two pipes, opening the one and closing the other.
q, r, is a water-balance, that moves on its centre s; and by which the two cocks o, and p, are alternately turned.
t, u, and w, x, are two air-pipes of lead, both internally one inch and a quarter in diameter.
y, z; y, z; y, z; are water-pipes, each being one inch in diameter.
The pipe b, c, c, is always full from the stream a, b: the small cisterns g, i, l, and the large one d, are supposed to have been previously filled with water. The fluid may then may be admitted by turning the cock o, through the pipe c, e, into the large cistern e. This water, Dr. Darwin remarks, will press the air, confined in the cistern e, up the air-pipe w, x, and will force the fluid out of the cisterns g, i, l, into those marked h, k, and C.—At the same time, by opening B, the water and condensed air, which previously existed in the large cistern d, and in the smaller ones marked f, h, k, will be discharged at B.—After a short time, the water-balance, q, r, s, will turn the cocks, and exclude the water, while it opens the opposite ones: the cisterns, f, h, k, are emptied in their turns by the condensed air from the cistern, d, as the water progressively enters the latter from the pipe, b, c.
In the year 1783, an excellent engine was erected at Windsor, by the command of His Majesty, for the purpose of raising water from a deep well, to supply the wants of the Castle. It consists simply of a grooved wheel, 3 feet in diameter, which is fixed on an axis that revolves horizontally over the well: an endless rope, sufficiently long to reach into the water, is passed over the wheel. Farther, a winch is attached to one end of the axis, by means of which it may be turned; and, on its opposite extremity, there is another wheel, weighted with lead, that acts as a fly, and serves to increase the velocity. When the wheel is turned, every part of the rope is drawn through the water, and ascends to the top, carrying with it a considerable quantity of that fluid: thus, by the pressure of the rope on the wheel, during its revolution, the water is discharged into a cistern placed for its reception.—This expedient was suggested by a sagacious mariner; and so remarkable is the facility with which the whole may be worked, that, though the well is nearly 200 feet in depth, the machine may be turned by one hand, and sufficient water be raised to fill a pipe; the diameter of which is equal to that of the rope.
In those situations, where it is an object of some importance to raise water to the height of a few feet, by the power of the wind, for the purpose of draining morasses, or of watering lands on a higher level; we conceive the horizontal wind-mill, with a centrifugal pump, to be a most useful machine: we have therefore annexed a representation of it, similar to that given by Dr. Darwin, in the work above quoted.
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