A jar can be made receiving and discharging a greater quantity of liquid at one time than at another, and in such a way that, when wine and water are poured into it, it shall discharge at one time pure water, at another time unmixed wine, and, again, a mixture of the two. Its construction is as follows. Let A B (fig. 8) be a pitcher having a partition in the middle, C D. In the partition, near the circumference of the vessel, let small holes be pierced in a curve, as at E. In the opposite side of the partition let there be a circular aperture, F, through which the tube F G H is to be inserted, being soldered into the partition, and reaching nearly to the bottom of the vessel at G. Let the other mouth of the tube H issue at the side of the pitcher, under the handle, and be soldered into the handle which must be hollow, and have a hole on its outer surface at K, which may be closed with the finger when necessary. If, then, closing the vent, as before, we pour any liquid into the jar, the liquid poured into the upper chamber will remain there, not being able to continue its way through the narrow holes into the lower chamber, as there is no other outlet for the air than through the vent K. When, however, we unclose the vent, the liquid will descend into the chamber beneath, and then the jar will hold more. If, then, we first pour in wine so as to fill the chamber B C D, and then, closing the vent, pour water upon it, the two cannot mix, and if we invert the jar it will emit pure water. But, when we unclose the vent, the water continuing to flow, the wine will flow out also, since air can enter through K to fill up the void left; and afterwards the wine will flow out unmixed. We may also pour in the water first, and then, stopping the vent, pour wine upon it, so as to pour out wine for some, wine and water for others, and mere water for those whom we wish to jest with. 9. _A Water Jet produced by mechanically compressed Air._ [Illustration: Diagram of apparatus as described in text]