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

THE SUN, LONDON, WEDNESDA

TUE LATE STEAM BO NT

EXPL()S101:.

ADJOURNED INQUEST.—(THIS DAY.)
The inquest on the bodies of the unfortunate
persons who lost their lives by the recent explosion
of one of the boilers of the Cricket, was renewed to-
day at ten o'clock in the board-room of St. Martin's
workhouse, before Mr. Bedford, the coroner.
Mr. M. Chambers, Q.C., Mr. James, and Mr.
M'lntyre attended for the respective parties as at the
last meeting.
The first witness examined was Mr. Edward
Portwine, of 27, Catherine-street, Pimlico, a writer
on engineering. I am not a working man. lam
not a practical man. I visited the whole of the boats
while they were working at a penny. I judged that
they were dangerous boats from the high pressure on
the boiler. The gauge was from thirty-six to thirty-
seven, and I thought that pressure too great to be
safe for marine boilers of three feet diameter. I con-
sulted several eminent men on the subject, and they
agreed with me. I told the engineer that that
pressure was too great to be safe. I did not notice
the valves.
By Mr. Le Breton—The boat was moored at Lon-
don-bridge, taking in passengers when I examined
the boilers and found the mercury gauge at 36.
To the jury—l never knew engines worked at
such a pressure-27k is the highest-23 is enough. I
am neither a working man nor a practical, but Dr.
Lardner is not a practical man. I have had great
experience.
By Mr. James _Locomotive engines work from
35 to 80. The book you hold in your hand looks
like mine-26 lbs pressure is not much for high
pressure boilers. I have said in my book that the
Cricket was worked with low pressure condensing
engines. I say so now—that the boat has been worked
at high pressure with low pressure engines. I did
not examine the engines or the boilers. I obtained
my information from the engineers of the boats.
The CORONER interfered. He said he thought that
the examination of the witness need not be pro-
ceeded with.
Mr. James said it was material that he should
proceed with his cross-examination.
Mr. Jones, the foreman, though the evidence good
for nothing. Mr. Portwine merely gave the result
of inquiries he had made, not the result of his per-
sonal investigation.
The CORONER considered such an observation pre-
mature. _ _

The examination of the witness was not, however,
after some discussion, proceeded with.
Mr. Thomas Lloyd, of the Admiralty, Somerset-
house, chief engineer and inspector of the machinery
of the navy, was next examined—He said, I have
examined the machinery and boilers of the Cricket
by the direction of the Government. I examined the
boat the first time the second Monday after the ex-
plosion, the 6th of September. (The witness here
handed in drawings of the vessel as she appeared when
he first saw her ; also a plan of the boiler and of the
safety valve, with the weight and size, which were
received in evidence ; also a drawing of the spring
balance upon the boiler, which did not burst
(Salter's balance) ; also a drawing which he
had received from Mr. Joyce, showing the
boilers in their orignal state (Mr. Hughes brought
specimens of the iron of the boiler, and pieces of
good plate). With regard to the engines, Ido not
think it necessary to say much about them. The
engines were high pressure, on the principle well-
known as Woolff's. There are two cylinders to each
engine ; one cylinder in which the steam is used at
a high pressure, and instead of passing into the open
air, as in ordinary high pressure engines, it passes
into the second and larger cylinder, from which it
passes into the condenser ; it is there condensed in
the ordinary way. The object of this arrangement is
the saving of steam, and therefore of fuel. So far as
I saw, the material and workmanship of the engines
were good. As compared with high pressure engines
of the ordinary construction, there is nothing objec-
tionable in them in point of danger. lam about to
say that there were attached to the engines two
pumps for feeding the boiler; there was another
pump worked by an auxiliary engine, which
is commonly called " the donkey," and a
fourth pump to be worked by hand, all for
feeding the boiler. I see nothing objectionable in
them. They appear to perform all that is necessary.
With regard to the boilers I may say that there were
two, consisting of an external cylinder, five feet in
diameter, having spherical end at the back, and the
front being composed of a flat plate, to which are
affixed a cylinder, composing the furnace, and also
small tubes, through which the products of combus-
tion pass. The internal part of the boiler, consisting
of the furnace, fire-box, and the small tubes, were
secured to the shell by rivetting round the circum-
ference of the front plate. The stay was fixed to the
end of the boiler, and the other obliquely to the top
of the front of the upper part of the shell. There
was a steam-door also rivetted to the top of each
boiler, on each of which there were two safety valves,
pressed down by levers, one lever having a weight
at its end, and the other a a spring balance—Salter's
balance. The thickness of the tube-plates was
about three quarters of an inch ; the front
plates, at the top and bottom of the boiler, three-
eighths of an inch, the shell three-eighths of an inch,
the steam door 5-16ths of an inch, the angle iron of
the boiler is three inches by a half, all the other angle
iron is two and a half by three-eighths. The rivets
are three-eighths of an inch thick. The rivets in the
boiler were three quarters of an inch. Assuming
each boiler to be of the power of 16 horses, the total
surface of the boiler is 14 3.loths per square foot.
The area of the fire grate is 55-100ths per foot horse
power. There is nothing objectionable in these pro-
portions of the boiler. The quantity of water in the
boiler up to the middle gauge cock is about 3-10ths
of a cubic foot, and the steam-room about 1i foot per
horse power. I have calculated the pressure upon
the safety valves to be, supposing the weight to be at
the extremity of the lever, per square inch amounts to
661bs per square inch very nearly. Taking the
spring balances as it was when I saw it, the pressure
per square inch, when the valve was just about to open,
would be, I think, 401bs. per square inch ; but if the
valve was wide open this spring balance would pro-
duce a pressure of about 1701bs. per square inch,
supposing the valves to be as wide open as they could
be. The wider the valve opens the greater is the
pressure upon the spring balance. A pressure of llb.
on the valve produces a pressure on the spring ba-
lance of 21bs. I will now describe the condition of
the boiler that was burst. The valves act separately,
and I apprehend if all the valves had been in proper
operation the steam could not have generated to a
dangerous extent.—(Sensation, and slight approba-
tion.) The power of the lever is as 101bs to 1 nearly.
This is not the usual way in which spring balances
are used, at least so far as I know. It would not be
liable to be easily disorderded. It is wrong in principle
to place a spring balance at the end of a long lever,
because the pressure of the valve is increased very
materially. I object altogether to the valves being
under the care of an engineer, but it is right to say
that the practice is too common.
CORONER—This is a valuable opinion, because it
may lead to a remedy of the evil.
Mr. Lloyd—l think, Sir, it can scarcely be a
matter of opinion. If it was intended to work the
boiler at 661b5., such a weight as the one I have de-
scribed ought not to have been put on the lever. I
am speaking of the lever with the weight. The spring
valves can be regulated to any pressure. The weight
being on the lever, would lead the engineer to the
inference that he might use it as he thought fit.
With regard to the construction of the boiler, I may
say that it was dangerous to be used as a high
pressure boiler. The whole of the pressure of the
steam within the boiler is brought, either directly or
indirectly, upon this flat plate in the front. I find,
when the pressure is 66, the direct pressure upon this
plate is 83 tons.—(Great sensation.) This pressure
is withstood by the thickness of the plate, with the
addition of the two stays I have mentioned. Ido
not believe that 661bs. to the square inch would
have hurt the boiler at the time it burst, but
when it got older it would have burst. In
the first place, you cannot calculate what
the pressure ought to be on the flat plate.
The pressure upon the inside tends to produce three
different effects ; in the first place there is a strain
brought upon it at right-angles from the surface. If
the plate was perfectly rigid, there could be no other
effect than this, but if not, an enormous pressure is
brought upon it on its own plane. I may illustrate
this by comparing the strain to that on a musical
string, when it is pulled lengthways. There is a
third action upon it produced by the bending of the
plate—the outer circumference remaining plain, the
inner part being considerably bulged. I have come
to the conclusion, from the best examination that 1
can give to it, that thtsfrtoho front
boiler,plate, wwiatsh thenot two
sufficientvery
imperfect stays put into
to bear for a length of time—that is, during the time
boilers usually last—a pressure of 601bs. upon the
square inch ; it could bear it no doubt at the present
time. Supposing the lever valves were tied, and a
man could easily stop the others with a small wedge
of wood, I have made rough calculations of the effect
aosfsuknelepptiinogns. alllftthhe e valves tied for five minutes—l do
not pretend to accuracy, because you must use
pressureof fiso
, minutess 6 0 whenit would the
be
valves
were tied, at the end9o;
and in ten minutes 130 to 140; in a quarter of an hour,
180. I cannot conceive four valves sticking at the same
time—one would not relieve the boiler sufficiently,
looking at the construction of the steam-pipe—that is
if three were fast. Two ought to remove the boiler,
one cf Salter's and one of the other. The area of the
steam-valve is 5 or 8 inches, but the area of the
waste steam-pipe is 28 7-10ths only. If the two
levers were tied, and the spring valves open, I think
1 a dangerous pressure would be brought on the boiler.