Southport telegraph. [volume] (Southport, W.T. [i.e. Kenosha, Wis.]) 1840-1850, 1840-06-23

full application of the appropriate remedies. /
The first fact brought forward by Mr.. |
Qulnby which is sustained by the best
French and American authorities, is, the |
momentous one, that the expansive form Of |
steam in boiler is not a safe test Of the |
danger OF an explosion. Hence the com
mon satety-yalve and guage are liable to
induce false and fatal security.
French philosophers, and others, have
demonstrated by actual experiment, that
steam in contact with water may be sur
charged with heat, in which case the ex-
cess does not descend from the steam into
the water, but remains above, and NAV
have, and often does hare It's temperature
raised to I400 degrees Of Fahrenheit's
scale. This high and dangerous tempera-
ture is usually the effect OF the application
/ OF fire to some portion OF the boiler above
/ the level Of the water within it. It NAV
however, be created by the application of
intense heat to such portions Of the boiler
as are duly protected by water, when the
steam has no sufficient outlet. The ra-
tionale may be stated briefly thus: The
! temperature at which water bols depends
greatly on the degree of pressure 10 which
it is subject. If the pressure be Il pounds
to the square inch, it takes place at 2l2
degrees; il the weight Of two atmospheres,
or about twcnty-cight pounds to the square
inch be added, 1t requires $50 deg. Ii the
pressure be increased to Is atmospheres,
1t requires a temperature Of 400 deg. TO
convert water into steam. 1t should be
borne in mind that water expands 100
/ nr1t hill
and that when the pressure upon it exceeds
about 235 pounds, to the square inch it be-
comes Imprisoned, and retains its liquid
state, no matter how great the heat applied
10 IT, In this condition the heat ascends
rapidly through the water and sur-charged
the steam which may be heated as before
mentioned, to Il dull read heat or I400 deg.
The pilot on board the Ill lotcd Lexington
testified before the inquest in Newly ork,
that the steam pipe on the night of the Gi-
sastcr, "Was red hot" three feet above the
upper deck, and Of course was at least as
hot quite down to the boiler. The great
defect in the boilers Of the Lexington, New
England, and Pulaski, was, as we under
stand Mr.. Quinby, in the construction Of
their steam hues and chimneys so as 10 al
low them 10 be excessively heated by steam
and the contact Of fire.
Few are aware Of the extent Of the in
Jury done to a boiler by heating any por-
ton OF Il subject to the expansive force of
steam to the degree that is often DONE
Experiments in France and repeated in this
country with the same result, demonstrate
The momentous fact, that Iron heated to
! T. al =
strength, and if cooled under high en-
pansive pressure, It never regains its ORR
ginal tcnacity. This explains the cause
Of a great number Of explosions which
have appeared quite ineXplicabe. Lett
suppose that boiler has been fairly tested
by public steamboat insnect0: and found
to bear pressure Of 200 lbs. to the square
inch, AID that she be allowed to carry 100
pounds as safe limit. Now if from any
cause portion Of the boiler becomes great
ly heated, but from the timely discharge
of steam an explosion does not take place
and the portion of the boiler thus exposed
loses not five sixths but one third Of its
strength. 1t is obvious that, instead Of
bearing pressure of 200 I5s to the inch,
it can sustain only 1873 pounds. The Off
GERS Of this boat are anxious to on some
occasion 10 show the speed Of their craft,
and put on as they are allowed to, $50 Ibs
Of steam to the square inch, and Of course
a terrible explosion IS the consequences
The engineer testifies and truly (if he is
left to say anything about the natter that
the steam was ten degrees below what his
/ permit allowed him TO raise, and the in
! sPcctor testifes that the boiler sustained
pressure equal to eco pounds. to the inch.
Facts like these show conclusiyely that it
is the temperature Of the steam, and not It's
expansion which forms the true measure
OF safety, although it is important both
should be indicated at all times.
Mr. Quinby proposes two important pre-
ventives Of this extreme and dangerous
weakening Of steam boilers by over heat
/ ing them. One is to case with a water
tight iron sheath, the steam fue and chin
ney. which sheath is to be filed 18th wa
ter. This water is used TO supply the BOZ
Ter, and whatever heat it receives is oil
course so much saved for the use of the |
engine. The Philadelphia Tow Boats,' |
have boilers constructed after this plan, |
which not only have the advantage of far
greater durability and safety; but as the
heating surface of water is considerably.
increased by this arrangement, there is
quite saving Of fuel. This water tank is
not expensive, and had the William Glib
bons. the Pulaski, the New England and
Lexington been each supplied with one,
there is now every reason 10 believe that
their aw(III destruction with ca v,,,ax. -