In the base of the vessel A B C D let there be tubes leading from each compartment, W Y from M, Z A´ from N, and B´ C´ from X: the extremities of these tubes Y, A´ and C´, must communicate with another tube Y A´ C´, into which another tube, E´ F´, is tightly fitted, closed at the interior extremity F´, and having holes pierced in it opposite to Y, A´, and C´ so that, as the tube E´ F´ revolves, when the holes pierced in it coincide consecutively with the holes Y, A´, and C´, they may admit the wine contained in each chamber and send it forth through the outer mouth of the tube E´ F´. To the tube E´ F´ attach an iron rod, G´ H´; to this, at the extremity H´, solder a mass of lead, K´, and at G´ an iron pin, L´ M´, to the middle of which is fastened a cup, L, with the concavity upwards: let the interior of this be a hollow truncated cone of which M´ is the larger circle and N´ the less, and through this the pin L´ M´ is to pass. Take several balls of lead, varying in weight, and equal in number to the compartments M, N, X; and if we place the least of the balls in the cup M´ N´, it will descend by its weight until it touches the hollow surface of the truncated cone, causing the tube E´ F´ to revolve until the hole in it coincides with Y and admits the wine in the compartment M, which will flow as long as the ball remains in the cup, unless it be entirely exhausted: when we remove the ball the weight K´ will turn back and close the orifice Y, and the discharge will cease. Again, insert another of the balls, and the cup will descend lower and turn the tube E´ F´ further round until the hole in it reaches the hole A´, and then the wine in N will flow: as before when the ball is removed the weight K´ will run down and close the orifice A´, and the wine will cease to flow. If another ball still heavier be placed in the cup, the tube E´ F´ will be turned still further round, so that the wine in the compartment X will flow. It is necessary however that the least of the balls when placed in the cup should preponderate over the weight K´, or, in other words, be able to cause E´ F´ to revolve; for then the other balls will preponderate and move E´ F´. 33. _A self-trimming Lamp._ [Illustration: Diagram of apparatus as described in text]