18. _Drinking-Horn from which either Wine or Water will flow._ [Illustration: Diagram of apparatus as described in text] There is a kind of drinking-horn, such that if wine be first poured into it, and then water, sometimes the water flows out unmixed, and sometimes the wine. The following is the construction. Let A B C (fig. 18) be a drinking-horn, furnished with two partitions, D E and F G: through both of these let a tube, H K, pass, soldered into the partitions, and pierced with a small hole, L, situated a little above the partition F G; and under the partition D E let there be a vent, M, in the side of the vessel. If, when these arrangements are complete, we close the passage at C and pour in wine, it will pass through the vent M; and, if we cover M with the finger, the wine in D E F G will be retained. Now, if we pour [water] into the part A B D E, still closing the vent M, pure water will flow out; but if, while the water is still in the upper part of the vessel, we unclose M, a mixture will be discharged; and when all the water has passed out, the stream will be of pure wine. By frequently unclosing M the discharge may be varied: but the better method is first to pour water into the chamber D E G F, and then, closing the vent, to pour wine upon it. The result will be that sometimes pure water flows out, and again, when the siphon is set free, a mixture; presently, on stopping the vent, pure wine. And this can be done as often as we please. 19. _A Vessel containing a Liquid of uniform height, although a Stream flows from it._ [Illustration: Diagram of apparatus as described in text]