, 1865-11-29
EXPLOSION OF BOILERS.
heCause Observation-Disclosures E1-
perfments ON the Steamer st. John-
Letter from mr.. Wtards

pertmentH ON the Steamer st. John-
Letter from mr.. Wizard.
From the \. I. Commercial Adserti.er.l
NEw YoRK, Nov. 2.
On the third Instant wrote paper, whIc,,
you were so kind as to publish, on Boiler
Explosions" a subject that was at that time
exciting deep interest, because Of the recent
disaster on the 5t.John.
In that paper asserted, IN effect, that ex-
plosons IRE not due:
lat To the direct pressure OF steam, fos Il IL not
The weakest pat lhnt gives Way; nor,
"a. TO The deeompoeltlon OF steam, irving It
tho quality and Character OF an explosive gas;
Sd. To the overhea,ing OF the boi1ersplstes; nor,
eet1ns water heated plates after The waierhas
been low for previous time; nor,
= sth, To The projection ofa lan:eamounl of..solid
Water" with momentum aca,nst tho shell or tho
boiler, when the pressure relieved suddenly rem
The snEace; ncr,
gih- To the myrterious action OF electricity: nor.
Iih- To new sudden increase Of steam from Tho
surplus hes. Sefng ths wstsa uasn 'Ae
nls0 explained that such accidents wcre
caused BY tho unequal expansion Of the boiler
plates, between the parts above and below
the surfnce Of the water, ut the time of the
nary water line, or lower, when there was q
deficiency Of water, Or higher when the water
was foom1ng; which theory has been tFj-
umphontly confirmed by experiments con-
Quoted On the came steamer during her Inst
round trip from New York to Albany and
buck, ending this morning.
On AondAy last. assisted by the most friend
y co-operation of Capt. St. John and Capt.
Smith, of the Peoples Line, Capt. Peck and
Chief Engineer Hook, OF the st. john, l In
serted number Of carefully prepared ther-
momete1s In the larboard boiler Of the St.
John, the same one to which the accident oc-
Cured. During the run up to Albany but
little attention was paid to the Indications Of
the Thermometers, ns they were adjusted In
nearly horizontal position, and lost conil-
dence In their reliability. which error was
corrected yesterday Mt Albany, and afler light
Ing the fires for the return trip, careful OBJ
serVnuons were taken md written down ut
short intervals during the night; 176 degrees
Fahrenheit was the highest temperature ID tho
boiler below the whole trip, while in the
steam the temperature ragged from Us to SO
degrees, and when We passed the place In the
river where the explosion occurred before,
thermometer placed twelve inches above the
place ofrupture exhibited temperature of5OO
degrees, while twelve inches lower down the
water was at atemperature Of 2Go degrees, its
surface osc1lating up and down SIX inches, al
ternateiy heating the plate by exposure to
the hot steam, and cooling II with tho water.
The certain effect of such expansion and
contraction In iron plntes, Is to permanently
weaken them; but the most dangerous weak
ness occurs to q plate in q boiler Just at the
instant Of cooling, uud consequently con-
trnctiug tho lower part Of sheet, 'shi1c the
upper part remains expanded by heat, when
few pounds pressure Of steam inside Is sutt-
Gent to complete the rupture. When the cold
water test il applied, the sheet is In state Of
i,iltal rest, aud its whole strength reslsss the
pressure Of cold water from within the boiler.
THIS It Ia easy to sec why this boiler with
stood the Inspectors pressure OF dfty-Eour
pounds, and atterward gave way to the cla.-
tic pressure OF steam at twenty eight pounds.
The water pressure test, then, does not pro-
valve will not relieve this atrain on the boiler
II may occur when tho water guages show 4
!: proper quality of wafer In the boiler. The
steam gage only shows tho pressure, 62t the
temperature Of the steau1- The boller-maker
cannot make boiler strong enough to with
stand this mysterious force, for the thicker
the plate the greater tho force. Stronger
unequal expansion, for their direction must
be i: right angles TO the direction Of the force
to be restrained,
The proper remedy, then, is sslterident.
Instead of charging boiler. makers with fraud
or want Of skill, and Inspectors firemeu and
engineers with carelcssness or inct1icfency, let
ns. el1alke the temperature throughout
the boiler. This i is easy to do, aud cor
Tects the whole difficulty aud avoids the dan
ger. Steam, at temperature Of 80 degrees,
Is condensed in low pressure engine lDs1au-
taneously BY the Injection Of wafer at 80 de-
gEees or lower Then let US hare q
shower OF water at temperature Of
269 degrees, falling down. within the
steam-room Of the boiler, In which
We carry thirty pounds pressure Water, at
that temperature, will not reduce the pres
sure below thirty pounds, because that Is the
proper heat OF steam at that pressure and as
the water and satu1nted steam always have
the same Temperature within boiler, no
matter what Is the pressure, II we pun up.
the water IN the boiler TO fall Ike q shower
bath in tie steam-room, the surplus heat Of
supeEheated steam would unite with the
Waeer, the resulting temperature would b.
uniform and the pressure be but little effected
This is merely general statement Of one
plan, without details, to show that remedy
is possible and practicable. The boilers O
the st. John will be Immediately supplied
With selracting device certain 70 M eqaansse Mas
.he temperature after which It nay 20 ~ So M
NoKuAy WARD, No. ID Fine street,