Phenix gazette. [volume] (Alexandria [D.C.]) 1825-1833, 1826-04-12

/ conclusion that excessive dangers must attend
the generation and use Of Perkins steam.-
The very reverse, however, experience has
proved to be the fact; on which account Per-
kins' engine, now nearly IL months at work,
has been named the Safety Steam Engine;" an
appellation which, as will be shown, cannot be
Justly applied to any steam engine hitherto con-
structed
| We shall proceed to explain the manner in
which the exp losions Of both high pressure and
low pressure steam engine boilers occur. and
the principle adopted by Mr. Perkins to obvi-
ate the danger.
| In low pressure steam engines, so much i'm
proved by that great philosopher and mechan-
ic, the late Mr. Watt, whose memory the ma
ton has, most honorably TO its bes, feelings,
recently commemorated, steam was rarely, if
ever, employed by him exceeding pressure
of twenty pounds to the square inch. From &C
| cidental causes, which can scarcely be guarded
against in practice, such as the safety valves
getting out of repair, the want of a due supply
Of water to the boiler, arising from the lmper-
lection of the pumps, or feed pipes, Sc the
steam in low pressure engines has too often
became converted into high pressure steam, of
| sufficient strength to burst the boiler and to
spread devastation all around. These terrific
consequences have originated from part Of the
steam, when of too great expansive force for
the boiler 10 bear, bursting that vessel, and the
remaining steam contained in the magazine,
usually consisting of a third or Fourth part of
the whole boiler, following up the shock, scat
,ers the fragments, as in the bursting of bomb
shell, in all directions,
The power, even, OF exceedingly weak steam,
as compared with Perkins high steam, may be
cxempliied from the fact, that part Of boil
err which some time since burstcd in Cornwall,
exceeding two tons in weight, was thrown clear
over high house adjoining the engine house,
and fell some hundred yards distance In like
manner piston, Of nearly half ton weight,
which had become damned in its cylinder,
could not be started with the greatest mechan-
ical power that could be applied to it. The
engine man having heated up his steam to fifty
or sixty pounds pressure to the inch, applied it
under the piston; the result was that it tore the
piston from all its strong connections to the
engine, carried it through the roof Of the house,
together with the engine man, and propelled it
| several hundred yards distance. If then, as can
be proved by indisputable evidence, that this
comparatively weak steam has effected what is
here related, it would argue determined dis.
INCLINATION to admit the power ofPerkins' high
pressure steam; which, as already stated, was
carried up beyond 500 lbs. TO the inch, were
it doubted that it could propel cannon balls with
equal superiority of force to gunpowder, as it
did there of the musket
The usual high pressure Engines have been
found much more dangerous than low pressure
engines; and, in consequence OF the frequent eX-
plosions which have occurred in the manuiac-
turing districts within the last year, indictments
have been indiscriminately preferred against al
high pressure engines The origin OF the in
creased danger orig mates not only from causes
similar to those already enumerated, 10 which
low pressure engines are table, but as the steam
employed is considerably beyond 30 lbs. to the
inch, and as cast iron boilers are more common
ly used in high pressure than in low pressure
engines, it is obvious that explosions of the lat
ter happen more frequently than of the former;
ana that when they do occur, the consequences
are usually more destructive.
Mr.. Perkins avoids all these dangers, by SUBJ
situting instead OF a steam boiler, what he has
designated steam generator A steam boiler i,
a very large vessel, generally made Of copper or
iron sheeting, sometimes Of cast iron, tanning
hogshead Of water for each horse power, to
be exerled by the engine The upper, third, or
fourth, part of this boiler is appropriated as
magazine for the reception of steam. Conse-
uuenlly, as every square inch Of this immense
extent CT surface has the pressure Of steam up
on ii, whatever that pressure may be, and as
the difficulty of preserving strength is in pro-
portion to the extent of surface exposed, hence
NAV readily be accounted for, the frequent ex-
plosions Of steam engine boilers which have oc
Cured MIR. Perkins steam generator consists
of series of very strong tubes, OF peculiar
construction made TO contain less than gal
lon of water to horse power OF his engine,
which tubes are exposed, by The most advanta-
gcous arrangement, to the action OF fire The
water is forced through them, while it is at the
same timc kept in contact with the sides OF these
tubes. whereby it is made to imbibe so high
degree of temperature as to occasion 1t 10 flash
into very powerful steam as soon as released
from pressure, in similar manner as gunpow-
der becomes converted into explosive gas on be-
being ieni,ed Instead OF keeping at times,
large magazine full Of steam, as in steam engine
boilers, MIR Perkins, on the contrary retains his
(fsura,ively spesking) red hot ~ater under sui
fcient pressure to prevent it from flashing into
Steam until it is wanted for use, when he instan-
taneously generates this elastic body, in the
quantities required to work his engine, or to
pronel his balls Hence Perkins steam gene
rator does not admit of a larger quantity OF
steam beng generated at time, than can be
contained m an iron tube Of very great strength