[Illustration: Diagram of apparatus as described in text]
Let us now proceed to construct the necessary instruments, beginning
with the less important, as from the elements. The following is a
contrivance of use in pouring out wine. A hollow globe of bronze is
provided, such as A B (fig. 6) pierced in the lower part with numerous
small holes like a sieve. At the top let there be a tube, C D, the
upper extremity of which is open, communicating with and soldered into
the globe. When it is desired to pour out wine, with one hand grasp the
tube C D near the mouth C, and plunge the globe into the wine until
it is wholly immersed. The wine enters through the holes, and the air
within, being driven out, passes through the tube C D: and if, pressing
the thumb on the aperture C, you lift the globe out of the wine, the
wine contained in the globe will not flow out, as no air can enter to
supply the vacuum, for the only entrance is through the mouth C, which
is closed by the thumb. When, then, we desire to let the wine flow, we
remove the finger, and the air, rushing in, fills the vacuum produced.
If we again press the finger on the air-hole C, there will be no
discharge until we once more remove the finger from the vent. We may,
in like manner, dip the globe into hot or cold water, and then retain
or let out the contents at pleasure, until all the water within is
exhausted. If the extremity C of the tube C D is bent, the action will
be the same, and it is then easier to stop the orifice with the finger.
7. _A Vessel for discharging Liquids of different temperatures at
pleasure._
[Illustration: Diagram of apparatus as described in text]
By the same means it is possible to discharge from the same globe
both hot and cold water in any quantity. The globe A B (fig. 7) is
constructed as before, but furnished with a perpendicular partition,
C D, dividing it equally. At the top a tube, H F, soldered into the
globe, communicates with the interior; this tube is also furnished
with a partition, C G, a continuation of the partition C D, and its
openings, H, K, must curve over in the directions C and F.
On each side of the partition C D, at the bottom of the globe towards
D, let holes be made like those in a cook’s ladle. When it is desired
to draw hot water, take the apertures H and K by the two fingers and
plunge the globe into hot water, and then unclose one of the vents,
H, that the air in the hemisphere B C D may be driven out through H:
the hot water, entering through the holes, will fill the hemisphere
B C D: again stopping the vent H take the globe out of the water,
and its contents will be retained, as the air has no entrance. Then,
in like manner, plunge the globe into cold water, unclosing the vent
K, and, when the hemisphere A C D is filled, close K and draw the
globe out. The globe is now full of hot and cold water, and when it
is desired to discharge either of these, unclose the proper vent: in
like manner close it again when the discharge is sufficient; and this
may be repeated till the contents are exhausted. In the same way it is
possible to draw up into and discharge from the same vessel wine, and
cold or hot water, and anything else whatever, at any time, and in any
quantity, by making the necessary partitions and orifices through which
the air may enter into each chamber and leave it again. Instead of the
curved outlets, holes may be made in the upper part of the sides of the
tube in various directions; and these holes are of course to be closed
when it is required to shut out the air. That the holes pierced in the
bottom of the vessel may not be seen, both sets may be included in one
channel, so that both streams may appear to flow from the same source.