3.460

1,470

•75

632


82*
63'

110' 1

ver



2J0



Maxims and instruelions.
TOOLS trSED IN STEAM FIlTINa



n»iA



COOKS.
The first means in the
earliest times of Bteam engi-
neering, for opening and
shutting the passages in
the pipea of steam engines
were cocke; and these were
all worked by hand and re-
quired close attention. A
boy named Humphry Potter
being in charge of one of
the cocks of Newcomer's
pnmping-engines, and desir*
ing time for play, it is said,
managed to fasten the lever-
handles of the spigots by
means of rods and string to
the walking beam of the
engine, so that eacli recurrent motion of the beam effected the
change required. This was the first antomatio TalTe-motion.
VALVES.
Tlie valve ia any de-
vice or applianeo used
to control tlie flow of
a lif[iii(l, vapor or gas,
tlirongh a pipo, outlet
or inlet in any forin of vessel. In this sense the definition in-
cludes air, gas, steam, and water eocka of any kind.
The bellows was probably the first instrament of which they
lormed a, part. No other machine equally ancient can be
pointed out in which they were required.
By far the most important improvement on the primitive
bellows or bag was the admission of air by a separate opening
— a contrivance that led to the invention of the valve, one of
the moat essential elements of steam, of water, as well as pneu-
matic machinery.
