The Liverpool Standard and General Commercial Advertiser.
Liverpool, Merseyside, England, 1842-11-18 00:00:00

O'CONNELL AND THE RADICAL FEED

Sirs—l'm just come from Jones, who, while cutting my hai
Said, in spite of the dinner—no Daniel was there
Pray, how did it happen—Great Daniel (M.P.)
Staid so long in the ship that his seat wa
We had Pike and Leviathan, which were _
And, yet, Dan and his Dens were, each, non est inventus
Yet, although they are cold, at least so I presume,
They again must come up for friend Daniel and Hume

That (whenever they come) t
shoulder "'
But Hum
The worl

•" out in his reckoning
ien mirelv's aonroachin

lust sent us

lit meet a

-who'll comprehend
to pm-I I

But its only when money is on the tapis
That Hume and his memory ever agree.
Would that Dan and his colleague, " Pounds-shillings-and-

pence,
Were out of their reck'ning ten thousand miles hence

But they say, sirs, that Daniel was in for his tea:
As he slandered your ladies, pray how can this be?
Be this ever your fate, poor unfortunate Dan!
To receive a " cold shoulder" from every man ;
And, instead of your tea. may each Englishman's daughter
Keep you. as you keep the whole land, in hot water ;
When we'll hope that, receiving this chastening rod,
You may turn from man to your Saviour and God;
To whom, turning for pleasure, or turning from pain,
The chiefest of sinners ne'er seeks Him in vain.;

THE POLYTECHNIC SOCIETY

This society held its monthyly meeting on Tuesday even
ing, the Bth instant, Mr. Platt (the treasnrer) in the chair.

SAFETY VALVE FOR ENGINE nouEns

The Secretary read an interesting letter received from Mr•
MAITLAND, formerly a member of the Polytechnic Society,
and at present residing at Montreal. The following are

" Shortly after my arrival in this country, a serious ex-
plosion took place of a steam boiler on a canal high-pressure

boat. The boiler was constructed on the locomotive ptin- '
ciple. The effect of the exPlosion took place immediately
behind the tube plate of the fire-box. The boiler had no
appearance that indicated that the explosion had taken place
from scarcity of water. The engineer, in evidence, declared
that he was allowed to carry Sslb., but there is no doubt but
that a much greater pressure than that would be required to
tear the boiler in the manner the Shamrock's was torn. The
boiler was constructed throughout ofa-inch plate. This,
there is no question, is too thin for tube plates. The tubes
were wrought iron. Prom all the circumstances of the case,
I have no doubt but the boiler exploded from a too great
accumulation of steam, and having either a too small or in-
efficient safety-valve, that did not allow it to blow off. From
this circumstance I was induced to pay some attention to,
and, if possible, to improve, the safety-valve. I send you a
sketch of one which 1 consider does away with many of the
objections of the present one in use. It is more especially
useful when steam of high pressure is used. If a valve is
constructed to he out of the reach of the engineer—that is,

to be loaded in the box that contains the val;:e, if the valve
be of any size at all—the weight requires to be enormous,
for a pressure is 15, 20, or 30 lb. per inch. In the valve I
have invented this objection does not hold, as the same
amount of weight will load .a 10-inch valve at the same
pressure, as it would load on the old plan a valve of 2 inches
diameter. This is easily seen from an examination of the
sketch. The top valve is shewn 10 inches diameter, and the
lower one 9i inch ; consequently the area to be loaded is only
a ring 10 inches diameter, and inch broad.—As the Poly-
technic Society is established for the advancement of science,
I will, if it would be of any service to its members, prepare
a paper on the system of marine engineering in this country.
The boats attain a speed here, with an economy of fuel, that
you have as yet not got at home. A boat was started this
summer on the St. Lawrence, called the Montreal : she is
the fastest in North America, Some engineers visited her
here from the Hudson, and they declared they had nothing
that surpassed her. She is 250 feet long; breadth, or beam,
27 feet ; depth of hold, 10 feet ; diameter of cylinder, 57
inches; length of stroke. 10 feet ; diameter of wheel, 30 feet,
10 feet long, and depth of float, 2 feet G; strokes, 21 per
n-inute; steam, 25 lb.; speed, 15 miles per hour!"
Mr. WILLIAM FERNIHOUGII having drawn a large sketch
of the valve above alluded to, proceeded, with much ingenuity
and clearness, to contrast the merits of Mr. Maitland's safety-
valve with those of the valves HOW in use. This safety-valve
(he observed) is intended principally for marine engines
working with high-pressure steam, (such as the American
steam-boat engines,) or, indeed, for any large high-pressure
engines, in which the, difficulty of applying a safety-valve on
the usual construction is well known—arising chiefly from
the large weight required to keep down a valve of only
moderate size against steam of such high pressure as 50 or
GO pounds per inch.
Mr. Maitland's valve consists of a very simple and ingeni-
ous modification of the common equilibrium valve, now well
known and much used among engineers. Steam from the
boiler enters freely a flat chamber, the top and bottom of
which are formed.by two valves firmly connected together,

and both opening upwards. Now, if these two valves be of
equal diameter, the steam pressure above the lower valve
will exactly counterpoise the pressure beneath the upper
valve, consequently the valves will have no tendency to rise,
and no steam will be allowed to escape. But if we suppose
the upper valve to be even one-eighth of an inch the larger
in diameter, the pressure on it will overcome that on the
lower valve, and the two valves being connected together,
they will both .ritse, and allow the steam rapidly to escape
(upwards throUgh the upper valve, and downwards through
the lower one); end it is evident that the weight necessary
to load this valve is exceedingly small, viz., just sufficient to
balance the pressure on an area equal to the difference be-
tween the areas of the two valves, whilst the valve is as
efficient as a common safety-valve having an area equal to
the sums of the areas of the two valves.
The force necessary to keep this valve down is so small,
th

at the ordinary lever is dispensed with ; and in place of it,

a weight 'corresponding to the pressure required is placed
immediately upon the top valve, thus preventing a tendency
to gag or stick from want of attention, and making the ap-
paratus what it really is—pre-eminently a sofety-valve.
Mr. FERNIHUIFIH'S able explanation of this valve was
listened to with great attention, and elicited much ,applause
at the close. The thanks of the meeting were voted to Mr.
Maitland—the same to be conveyed by him to the Secretary.
CORRECTION OF TEE COMPASSES IN IRON SHIPS.
Mr. SPENCE read an extract of a letter addressed to
Messrs. Gray and King, of this town; (opticians, &c.,) by
Captain Charleywood, of the iron steam-frigate Guadaloupe,
built at this port, and now (we believe) in the eervice of the
Mexican government. The letter was dated the 26th of
August last, and the gallant writer states with much gratifi-
cation, that the correction of the compasses by Messrs.
Gray and Co. was so effectual, that he had not found the
slightest inaccuracy in them during the outward voyage, nor
during his several trips in the South American seas. This
I is the more gratifying, inasmuch as the vessel is not only
(with the exeeption of the decks) entirely built of iron, but,
moreover, carries one of her two large guns (G8-pounders)
aft, and necessarily at no great distance from the binnacle.
The moving of this large gun from side to side when in use,
had but a very slight effect on the compasses at the moment
only. The same effect would be perceptible in any vessel
carrying guns ' • so that it may now be safely assumed that
the compass, if properly corrected, a priori, may be relied
upon as maintaining its accuracy, as well in iron as in
wooden ships—a great desideratum, particularly as regards
the future advancement of steam navigation. The plan
adopted is that of Professor Airey ; but the nautical world is
indebted chiefly to Messrs. Gray and Co. for bringing it by
long study and experiment to a practical and successful, re-
sult. _ _ . .

A brief discussion then took place on the spontaneous
combustion of iron under certain circumstances; also on its
conversion by exposure to salt water, or the fi ictfon of tube
metal, into plumbago, of which extraordinary mutation of its
particles some interesting explanations were given by Mr.
Smith, Mr. Spence, and others. The meeting then separated.

The Reverend Denis Browne, vicar of Santry, has been
promoted by the Lord Lieutenant to the valuable and im-
portant living of Enniscorthy, vacant by the elevation of the
Rev. John Whitbey Stokes, to the Archdeaconry of Armagh.
This is in every respect a good appointment, and well calcu-
lated to inspire respect and confidence in the government.
We learn too that the value of the appointment, which was
entirely unsought for, is considerably enhanced by the pe-
culiarly kind and gracious manner in which, by his Excel-
lency's desire, it was communicated to Mr. Browne..—
Dublin poper.

CORRESPONDENCE,

POST-OFFIC

DITOR C

lied to

POOL : S

o every ap-
. the follow-

a of your

he Christian

tually imposing.

ring the day to

.he most fatignin

m one of rest) the busiest-
It is a lamentable fact, that since the coni-

nt of this year, no fewer than s

he packets have arrived oftener on that
Surely, sir, these thin^s
here the remedy is so simple.
at this port, be

arrivals and de-

day than on any day in the week
ought not to be, especially wi
Let the sailing days, at Halifa
some fixe4

as well as
Friday), al

in the week (s

nd not regulated

ment the mails
become c

,uld never, in the

le at either por

R alteration could no

1 as it ot

t the London Post-offic

in the 11

not iwaginary ; no, but real, ir,