Vermont watchman and State journal. [volume] (Montpelier, Vt.) 1836-1883, 1853-02-17
Fire-Engines.

MEssRs. Walton & SoN Il thought it
might not be amiss TO say few words,
through your columns in reference to fire
engines, as it is a subject of considerable
interest TO our citizens, at the present time.
The plan ia general use is, the onion of two
pumps discharging alternately, into one
common air chest; each pump has two
valves, one inlet and one outlet, and there is
a tube inserted in the air chest, 10 conduct
the water to The leading hose. Suction hose
is frequently made use of to convey water
from reservoirs, &c. to the engines. When
the suction of an engine is immersed in the
water, and the atmosphere driven from the
pumps and none admitted to supply its place,
the weight of the atmosphere on the water
forces it to the pumps, TO any height so that
the weight of the water on the square inch
shall not exceed that of tie atmosphere on
the same area. The force required to supply
an engine through suction hose can never
be more than the weight of the atmosphere
on the working area of the pumps, and the
force required TO raise column of water to
any height can never be less than its own
weight per square inch on the working area
of the pumps, and to a height equal to the
weight ofthe atmosphere cannot be less than
the weight of the atmosphere on the working
area ofthe pumps. An engine must be air
tight to do good execution. Iftoo much air
is admitted no water can be raised to the
pumps by the weight of the atmosphere,
and if any air is admitted it lessons the
quantity of water discharged more than it
does the force required to discharge it ii
expands in the pumps by the force required
10 raise the water TO the pumps, and Is COM
pressed by the force applied TO drive the
water from the pumps. il passes to the air
chest with the water, and fills it to the base
of the conducting tube, destroying in part
its intended effect to produce a constant
discharge.
An engine may be air tight when work.
ing, and yet leak water by the pistons,
which costs as much force as it does to dis
charge the same amount from the discharge
pipe under the same pressure. Such a pro-
cess may well be called churning. An en-
CINE may never be said to be in good repair
unless the amount discharged is equal to
the contents of the pumps The effect pro-
duced by an engine that leaks AIR, when
compared with the same in good repair, is
not IN proportion to the force applied, nor
in proportion to the quantity OF water dis
charged, but in proportion TO its density
and velocity. A column of water free from
air passes on unbroken, only Increasing in
volume as it decreases in velocity. The
mixed column of water and air is dispersed
in proportion to the quantity of air and the
force applied, and spreads over too much
space at time to do much, if any good,
when applied to fire Of dense flame be
ing evaporated by the flames before it reach
es the burning substance. Hence, the ne
cessity of good engines in good repair
Poor ones are little better than nothing,
since they do not in all cases save the lives
and property of the unfortunate, bat too
frequently bring reproach upon those who
operate them. MECHANIC.
PLANK ROAD IN MoNTPELIER.-The