\Si"phon\, n. [F. siphon, L. sipho, -onis, fr. Gr. ??? a
siphon, tube, pipe.]
1. A device, consisting of a pipe or tube bent so as to form
   two branches or legs of unequal length, by which a liquid
   can be transferred to a lower level, as from one vessel to
   another, over an intermediate elevation, by the action of
   the pressure of the atmosphere in forcing the liquid up
   the shorter branch of the pipe immersed in it, while the
   continued excess of weight of the liquid in the longer
   branch (when once filled) causes a continuous flow. The
   flow takes place only when the discharging extremity of
   the pipe ia lower than the higher liquid surface, and when
   no part of the pipe is higher above the surface than the
   same liquid will rise by atmospheric pressure; that is,
   about 33 feet for water, and 30 inches for mercury, near
   the sea level.
2. (Zo["o]l.)
   (a) One of the tubes or folds of the mantle border of a
       bivalve or gastropod mollusk by which water is
       conducted into the gill cavity. See Illust. under
       {Mya}, and {Lamellibranchiata}.
   (b) The anterior prolongation of the margin of any
       gastropod shell for the protection of the soft siphon.
   (c) The tubular organ through which water is ejected from
       the gill cavity of a cephaloid. It serves as a
       locomotive organ, by guiding and confining the jet of
       water. Called also {siphuncle}. See Illust. under
       {Loligo}, and {Dibranchiata}.
   (d) The siphuncle of a cephalopod shell.
   (e) The sucking proboscis of certain parasitic insects and
       crustaceans.
   (f) A sproutlike prolongation in front of the mouth of
       many gephyreans.
   (g) A tubular organ connected both with the esophagus and
       the intestine of certain sea urchins and annelids.
3. A siphon bottle.
{Inverted siphon}, a tube bent like a siphon, but having the
   branches turned upward; specifically (Hydraulic
   Engineering), a pipe for conducting water beneath a
   depressed place, as from one hill to another across an
   intervening valley, following the depression of the
   ground.
{Siphon barometer}. See under {Barometer}.
{Siphon bottle}, a bottle for holding a["e]rated water, which
   is driven out through a bent tube in the neck by the gas
   within the bottle when a valve in the tube is opened; --
   called also {gazogene}, and {siphoid}.
{Siphon condenser}, a condenser for a steam engine, in which
   the vacuum is maintained by the downward flow of water
   through a vertical pipe of great height.
{Siphon cup}, a cup with a siphon attached for carrying off
   any liquid in it; specifically (Mach.), an oil cup in
   which oil is carried over the edge of a tube in a cotton
   wick, and so reaches the surface to be lubricated.
{Siphon gauge}. See under {Gauge}.
{Siphon pump}, a jet pump. See under {Jet}, n.

\Si"phon\, v. t. (Chem.)
To convey, or draw off, by means of a siphon, as a liquid
from one vessel to another at a lower level.