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 he a tube, C 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, when, 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 finger from the vent. We
may, in like manner, dlip 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.