[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]
If a goblet be placed upon a pedestal, whatever quantity may be drawn
from it, it shall always continue full. The construction is as follows.
Let A B (fig. 19) be a vessel, the mouth of which is closed just at the
neck, by the partition C D. Through C D let a tube, E F, be inserted,
reaching nearly to the bottom; let another tube, G H, be passed through
the bottom of the vessel, reaching nearly up to the partition C D; and
in the bottom bore a hole, K, to admit the small tube K L. The vessel
A B must stand upon a pedestal, M N O X, through which passes the
projection of the tube G H, and another tube S T communicating with the
pedestal and the goblet P R so that the goblet may be filled, and the
pedestal M N O X as high, &c. Now let wine be poured through E F into
A B (the air will pass out through G H), and, if the tube K L be left
open, it will pass through into the pedestal and the goblet P R: but,
if K L be closed, the vessel A B will be filled. Let, then, the wine
run into the pedestal M N O X and the goblet P R, so that the goblet may
be filled, and the pedestal M N O X as high as the mouth of the tube
G H. When this is done, close E, and the wine in A B will no longer
[flow] through K L, for no more air can enter through E to supply the
vacuum created. When, therefore, any wine is taken from the goblet, the
orifice E must be unclosed, and, the air having found an entrance, the
wine will flow again into the pedestal and goblet, until it is full.
And this may be done as often as we draw off wine from the goblet.
It will be requisite that a small hole be pierced in the side of the
pedestal at U, that an equivalent bulk of air may pass into the vessel
A B through the orifice G and the hole U.