The Sun.
London, England, 1847-09-22 00:00:00

After examining the boiler, I tested the goodness of
the materials by taking pieces which were rent when
it burst. They are 3-Bths of an inch thick. I cut
slips of two inches in thickness from them, both
with and against the grain, and tore them asunder by
a machine for that purpose at Woolwich. (The wit-
ness produced the slips.) I had four pieces of similar
thickness cut from a new plate of the same thickness
at Woolwich. The average strength per square inch
of the plates was 17 tons, and the strength of the new
plates of the same thickness was 21 and 2-3ds of a
ton. I tried also some common Lowmoor plates of the
same thickness, but of a far superior quality. The
Cricket's plates are lamaniated very much. This
occurs in the best boilers. The iron where the boiler
burst is bad ; in fact, the iron is of a kind that ought
not to have been applied to high pressure boilers.
I also tried some common Staffordshire plate,
as thick as the Cricket's, and it bore 16 tons and two-
thirds. The boilers are not properly constructed ;
the rivets generally did not fill the holes, and they
were generally not sufficiently long to make a good
rivet. The boiler does not seem deteriorated by
wear, except at the lower part, a portion of which
exploded. Ido not attribute the explosion to the
wear of the boiler. The whole front of the boiler
was blown out. Of course the boiler was weaker
than when new, but not much. No experiments
will tell us what pressure the front plate would bear.
The iron was not of good quality, considering the
use to which it was applied. Such iron is used in
the navy for parts of boilers not much liable to wear.
The pressure when the explosion took place could not
have been less than 136 to the square inch. It is
utterly impossible to calculate it exactly. I have no
reason to suppose that there was a deficiency of
water. The boiler was a tubular one. The bursting
of the tubes from which it derives its supply of water
could not cause anything serious. Tubular boilers
are generally considered safe if they are properly
used. Two or three were burst in the explosion.
The great objection I have to the boiler is its construc-
tion without proper staying, and in a far less degree the
materials of which it is male. The cause of the
explosion was an improper increase of the pressure of
the steam. If the steam increased from 60 to 150
in ten minutes, the explosion is easily accounted for.
I should say that the boiler had never been subjected
to so great a pressure as at the time it burst, because
the exploded boiler leaked materially, no doubt from
the pressure it received on the day of the explosion.
The boilers were connected at the lower part with
the water, and at the top with the steam. The pres-
sure on the two boilers was the same, and if but one
valve was in operation it would act upon both. I
may mention with respect to the unexploded boiler,
that the front plate was permanently bulged an inch
and three-quarters, and when subjected to the water
pressure of 186, it was bulged two inches and a six-
teenth, and began to break at the pressure I have in-
timated as being on the other boiler, and exactly like
it. If all the four valves had been at liberty, it ap-
pears to me quite impossible that an explosion could
take place. 1 think the valves must have been closed
either by accident or design, or merely open to a very
small extent.—(The witness here handed in a plan of
the state of the boiler before and at the time of the
explosion, and explained the mode in which it took
place.)
By Mr. IM. Chambers—The object of the spring
valve is not to save steam ; it is intended to act as a
weight. I don't disapprove of spring valves. I dis-
approve of the way in which they were placed in this
case. When the valves were not in the care of the
engineers, and they got out of order, they could be
raised, but not lowered. This is the plan adopted in
the navy since steam-vessels were used; it is not so
in locomotives. A man cannot, therefore, produce a
greater pressure. The "pressure on the unexploded
boiler was, I think, 401bs. There was nothing to
indicate that the valve was tied. The Salter's balance
was broken and carried away. If the Salter's balance
in both boilers had been in order at the time, I cannot
say whether they would have prevented the explosion.
I doubt much whether they would. I have come to
this conclusion from the strength of the springs and
from the smallness of the pipe; also from the steam
having to pass in two or three different directions,
which impeded its progress to the funnel. Any one
standing near the funnel could hear the steam blowing
off at a low pressure. I think there should be two
valves on each boiler, as*in this case. I certainly should
have preferred two weighted valves to the spring valves.
The gauge is intended to show the engineer the
pressure of steam. I should think it is liable to get
out of order ; if either water or air get in it will not
act properly. Besides the valves and the gauge, there
is nothing to show the engineer the pressure of
steam. The experiment I made on the front plate
was gradual—the lower plate began to break at 120
lbs. If that pressure had come suddenly in with a
jerk or a bump, the force would be materially in-
creased. There is " impact," the force of which no
one can calculate. I do not see how the pressure
could be brought on suddenly to entitle it to the
term " impact." There were two stays to the unex-
ploded boiler which were broken, and either sudden
or gradual pressure would break them. The sudden
breaking of one of the stays would perhaps cause a
bulging in the front, but I cannot calculate the
amount of pressure. I will not say that it would
be so small as not to create any effect. The stays
were not broke, the fastenings gave way. One of
the holes in the back stays was torn out
by the force of the explosion. I should
be very sorry to make any experiment
to learn the increase of pressure on a boiler the
valves of which were closed at 60, and for ten
minutes. I draw my conclusions from the quantity
of water, the dimensions of the boiler, the heat, and
from the experiments made by other persons, and cal-
culating the elasticity of the steam, I have arrived at
the opinion I have expressed. I have considered that
everything except the valves was in order; but I do
not pretend it to be considered as an accurate
opinion. I really did not notice that any of the
tubes had been plugged. The tubes, if they leaked,
would only let out water, and no escape of steam
would take place by them. The boiler is a tolerably
good one—that is the main consideration ; the state
of the tubes is not so material as that. If the pres-
sure had got to 80 or 90 the spring valves;would,have
been acted upon. They would operate at that pres-
sure. If they had been open, the escape of the steam
would have made a great noise ; but if they did not
let the steam off as fast as it was generated the sub-
sequent explosion would only be prolonged. A
stoker, if he were present, would in such a case
" draw his fire." lie knew no one who thoroughly
understood the steam engines. Engineers in the
navy were subjected to examinations. A good man
was a man who understood his work.
You must get the best man you can,
and if you cannot get him at low
wages, you must give higher. A man who could
take an engine to pieces, and who understood its na-
ture, would of course make a good driver, but if he
had not a perfect knowledge he might cause more
injury than an imperfectly educated driver.
By Mr. James—lf all the valves had been open Ido
not think that an explosion would have taken place.
My opinion is fortified from what I have heard that
something must have been done to the valves. The
evidence that no steam was blowing off, also leads me
to the opinion that the action of the valves had been
interfered with before the explosion. If the fact be
established that the valves were tied on the boat
leaving the pier, and that it rose to such a height that
the gauge became disordered, I should say it would
be conclusive as to the cause of the explosion. If all
the valves were in operation, 661bs. was the maximum
pressure on the boiler, which could be regulated by
moving the weight or the lever. In the
royal navy there are no levers—the weights
being underneath. I have no objection to an en-
gineer adjusting the pressure, unless he does so with-
out the cognisance of the parties interested.—(Salter's
balance was placed in the hands of witness.) He said
this is a better one than the one in the Cricket; it
showed 85, this showed but 45. The engine is better
known as Woolffs. It is not used in the navy. I
have no objection to high-pressure steam-engines.
They always have been used. Salter's balance is
used on locomotives. We have no high-pressure
engine yet at 'Woolwich. I prefer low-pressure, but
it is necessary to use high-pressure. This boiler,
for a high-pressure one, did not undergo a
severe test. I tried it without the stay.
I allowed something for corrosion. The maker should
allow something at the commencement. The angle
iron of the unexploded boiler was burst. I do not
attach the slightest importance to the stays in testing
the boiler. I was informed that the boilers had
been proved. Mr. Joyce and the proprietors of
theth e bhooaatt. afforded
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100. The iron of the Cricket bore seventeen
tons to the square inch. The Locomotive
bore an average of pressure of 21 and two. thirds—
the utmost was 22 and two-thirds. If I were com-
pelled to use square plates I should have them of a
thickness to bear the entire pressure of the whole
boiler. The tying of the valves would gra-
dually weaken the boiler, and therefore some
allowanee must be made in favour of the
maker. I made no experiments on the dome.
The vulnerable part of the boiler 'gave way. If I
were a commercial boiler maker I would not under-
take to construct a boiler to work with closed
safety-valves, neither would I work one. I
am going to make a report to the Board
of Trade. One stay is at each end
of the boiler, and both are inside. If
the engineer periodically tied down the valves, the
boilers must have stood a pressure which it is impos
Bible to calculate. The gauge would not, in such a
case, actually show the pressure. Many parties had