[Illustration: Diagram of apparatus as described in text]
Let there be a vessel filled with wine and provided with a spout
under which a drinking cup is placed: wine shall run into the cup in
any required quantity. Let A B (fig. 66), be the vessel containing
wine, and C D the spout, the upper surface of which at the extremity
C is so smooth that, when a valve in the form of a kettle-drum E F is
placed upon it, water is excluded. On the handle of the vessel fix the
vertical rod G H, on which, as on a fulcrum, another rod K L vibrates:
again place another rod, M N, under the pedestal, moving about the
point X, and attach two more rods K O, L P, moving on pivots in such
a way that, if the extremity M of the bar be depressed, the valve E
F is raised, and the spout is opened and sends out a stream, but is
closed again when M is suffered to return. Let the bar M N support the
drinking cup R, into which we wish to receive the given quantity of
liquid: the cup must be placed beneath the spout. Take a weight, S,
capable, by means of a ring, of being shifted along the projection M O
of the rod: and when S has been brought towards M, the spout will be
opened and send its stream into the cup, but as the cup grows heavy
the weight will be raised again and the spout closed. That the wine
may flow out in the required quantity, place in the cup any measure
of liquid, for instance, a cotyle, and, receiving what falls from the
spout in another vessel, shift the weight along the bar to the first
point at which the discharge from the spout ceases: make a mark on the
bar at this point and register one cotyle. We must proceed in the same
manner for a half-cotyle, and two cotylæ, and so on for other measures
as far as we please; and thus we shall have marks for the different
quantities, signifying the points to which the weight must be brought
in order that they may be discharged. Instead of the valve E F, an
air-tight vessel may encircle the spout, so that, as long as the liquid
is kept away by the air within, there will be no discharge through the
spout.