Section 63
No. 63. A Water-Clock, made to govern the quantities of Liquid flowing from a Vessel.
A VESSEL containing wine, and provided with an open spout, stands upon a
pedestal: it is required by shifting a weight to cause the spout to pour
forth a given quantity, - sometimes, for instance, a half cotyle (1/4
pint), sometimes a cotyle (1/2 pint), and, in short, whatever quantity
we please. A B (fig. 63), is the vessel into which wine is to be poured:
near the bottom is a spout, D: the neck is closed by the partition E F,
and through E F is inserted a tube, G H, reaching neary to the
bottom of the vessel, but so as to allow of the passage of water. K L M
N is the pedestal on which the vessel stands, and O X another tube
reaching within a little of the partition and
extending into the pedestal, in which water is placed so as to cover the
orifice 0, of the tube. Fix a rod, P R, one half within, and the other
without, the pedestal, moving like the beam of a lever about the point
S; and from the extremity P of the rod suspend a water-clock, T, having
a hole in the bottom. The spout D having been first closed, the vessel
should be filled through the tube G H before water is poured into the
pedestal, that the air may escape through the tube X 0: then pour
water into the pedestal, through a hole, until the orifice 0 is closed,
and set the spout D free. It is evident that the wine will not flow, as
there is no opening through which air can be introduced: but if we
depress the extremity R of the rod, a portion of the water-clock will be
raised from the water, and, the vent 0 being uncovered, the spout D will
run until the water suspended in the water-clock has flowed back and
closed the vent 0. If, when the water-clock is filled again, we depress
the extremity N still further, the liquid suspended in the water-clock
will take a longer time to flow out, and there will be a longer
discharge from D: and if the water-clock be entirely raised above the
water, the discharge will last considerably longer. To avoid the
necessity of depressing the extremity R of the rod with the hand, take a
weight Q, sliding along the outer portion of the rod, R W, and able, if
placed at R, to lift the whole water-clock; if at a distance from R,
some smaller portion of it. Then, having obtained by trial the
quantities which we wish to flow from D, we must make notches in the rod
R W and register the quantities; so that, when we wish a given quantity
to flow out, we have only to bring the weight to the corresponding notch
and leave the discharge to take place.
Section 64.
Index.