Let there be a vessel containing water, and a pipe in it provided with a key or cock, and let a figure float on the surface of the water; then if water, in any quantity, be drawn off through the pipe, wine shall flow from the figure in any given ratio to the water drawn off. Let A B (fig. 25) be the vessel of water, provided with a pipe, C, which admits of being closed; and on the surface of the water let a basin, D, float, in which is a perpendicular tube, E F, carved in the shape of some animal. Place near another vessel, G H, containing wine, in which is a bent siphon, K L M, one leg being within the vessel G H, and the other without, conducting into the tube E F. Now if we draw the wine through the lower mouth M, it will flow into the tube E F until the surface of the wine in the vessel G H and in the tube E F shall be at the same level. Let that level be in the line N X O P; and at the point P fix an open pipe, R. Hitherto there is no discharge of wine, but, if any quantity of water is drawn off through C, the basin D, and, with it, the tube E F will sink, and the surface of the wine [in the tube] will become lower than the surface N X; so that, the outer leg of the siphon being depressed, the wine will again pass on into the tube E F and run out through the pipe R. This will happen as often as we draw off water through the pipe C, the wine flowing in a fixed ratio to the water drawn off. The base of the vessel A B must bear the required proportion to the base of G H; and thus what was proposed is done. 26. _A Vessel from which Wine flows in proportion as Water is poured into another._ If it is required that the wine shall flow in a certain ratio to the water we pour _into_ the vessel, we must proceed as follows. As before let A B (fig. 26) be the vessel containing water, and G H that which contains wine, but let the tube E F be outside the vessel A B. In A B let a ball, D, float, from which a cord, passing over a pulley, S, is attached to the tube E F so as to suspend it; and let all else correspond with what was stated in the last paragraph. The result will be that, when water is poured into the vessel A B, the ball D rising will lower the tube E F, and the wine will flow again. This may be effected in a different manner by attaching the cord from the ball D, across the pulley S to another pulley, T and across that again to the siphon K L. It will be found now that, when the ball rises, the siphon K L M, being suspended by the cord, is lowered, so that, the outer leg having again become the longer, the wine will flow through the mouth M. [Illustration: Diagram of apparatus as described in text] 27. _The Fire-Engine._ [Illustration: Diagram of apparatus as described in text]