ut putting the vessel into dock, except by the use of Kingston's
valves, or some equivalent expedient.

472. Q.--What is the proper construction and situation of the injection
cocks, and waste water valves?

A.--The sea injection cocks are usually made in the same fashion as the sea
blow-off cocks, and of about the same size, or rather larger. The injection
water is generally admitted to the condenser by means of a slide valve, but
a cock appears to be preferable, as it is more easily opened, and has not
any disposition to shut of its own accord. In paddle vessels the sea
injection pipes should be put through the ship's sides in advance of the
paddles, so that the water drawn in may not be injuriously charged with
air. The waste water pipe passing from the hot well through the vessel's
side is provided with a stop valve, called the discharge valve, which is
usually made of the spindle kind, so as to open when the water coming from
the air pump presses against it. In some cases this valve is a sluice
valve, but the hot well is then almost sure to be split, if the engine be
set on without the valve having been opened. The opening of the waste water
pipe should always be above the load water line, as it will otherwise be
difficult to prevent leakage through the engine into the ship when the
vessel is lying in harbor.

473. Q.--What is the best arrangement of gauge cocks and glass gauges?

A.--Gauge cocks are generally very inartificially made, and occasion
needless annoyance. They are rarely made with bottoms, or with stuffing
boxes, and are consequently, for the most part, adorned with stalactites of
salt after a short period of service. The water discharged from them, too,
from the want of a proper conduit, disfigures the front of the boiler, and
adds to the corrosion in the ash pits. It would be preferable to combine
the gauge cocks appertaining to each boiler into a single upright tube,
connected suitably with the boiler, and the water flowing from them could
be directed downward into a funnel tube communicating with the bilge. The
cocks of the glass tubes, as well as of the gauge cocks, should be
furnished with stuffing boxes and with bottoms, unless the water enters
through the bottom of the plug, which in gauge cocks is sometimes the case.
The glass gauge tubes should always be fitted with a cock at each neck
communicating with the boiler, so that the water and steam may be shut off
if the tube breaks; and the coc