The Sun.
London, England, 1850-07-05 00:00:00

NEW WORKS AT KEYHAM.

For some time past a very interesting and satisfactory
series of experiments has been conducted at this yard,
to test the strength and other capabilities of the large
wrought-iron caisson which has just been completed by
Messrs. William Fairbairn and Suns, of Manchester, for
the south entrance to the new basins. As considerable
novelty and great ingenuity have been evidenced in the
design of this caisson, it may interest the scientific public
to have a short account of the principle of action, and of
the nature of the tests to which it has been subjected. It
is only right, too, now that the success of the scheme is
placed beyond doubt, that due merit should be awarded
to its originator, Mr. William Scamp, Assistant of Vorka
to the Admiralty, who has realised tz very important im-
provement upon the ordinary form of vessel used for the
purpose of closing the entrances to docks and basins.
The leading dimensions of the " monster" caisson
have already been given in this journal. It is, in fact,
a huge hollow iron box of the form of the entrance to
the lock, perfectly flat at the sides, 82 feet 6 inches
long at the top, only 13 feat 6 inches wide, and of the
enormous depth or height of 42 feet. The lower part
of this box is farmed into an air-chamber, or what
may be termed the lungs of the caisson, by a
strong iron deck which is carried from side to side at a
height of about 12 teat from the bottom, and made per-
fectly air-tight. The capacity of this air chamber is so
adjusted that when the caisson is immersed iu water.
the confined air exerts a buoyancy a little in excess of
the total weight of the ciasson ; and, as by means of
sluice valves the water is allowed to enter the in-
side of the caisson and fill it from the top deck of
the air chamber upwards to tho level of the water
outside, whatever that may be, it follows that at any
point of the tide, and with any depth of water greater
than that which would float it, the caisson would swim
a few inches clear of the masonry. The total depth
of the caisson is about five feet greater than the
depth of the water at the entrance to the lock at high
spring tide, and this space is made available for the
means employed for sinking and moving the caisson.
A watertight tank is formed in this part of the cais-
son capable of holding sixty to seventy tons of water
supplied to it from the water-main of the dockyard; and
it depends upon the presence or absence of this quantity
of water in the upper tank whether the caisson remains
firmly resting on the masonry and closing completely
the entrance to the lock, or fl oats a few inches clear cf
the floor ready to be hauled by capstans into the recess
in the earthwork which has been prepared.
The ingenious manner in which Mr. Scamp has
availed himself of this buoyant principle constitutes
the most meritorious feature of his scheme, for the
emission of the small quantity of water confined in
the top tank (which, by means of an ordinary valve
placed in its bottom. is accomplished in about two mi-
nutes) has enabled him to dispense with the laborious anti
expensive process of pumping, which has to be resorted
to in the case of the ordinary caisson every time a vessel
passes to or from the lock. It may be stated that had
the ordinary caisson been adopted at Keyhano, the
pumping would have required at each removal a force
cf from thirty to forty men for a space of two hours.
In the proportioning of the parts of the caisson the
Admiralty availed themselves of the experience of Mr.
Fairbairn, of Manchester, and the result has proved that
the caisson embodies within itself an amount of strength
adecoate to resist without injury the most severe
strains. In the course of the experiments the caisson
has twice resisted, in the presence of the Captain-
Superintendent, L rd John Hay, and all the Government
officers and contractors, the pressure on one side of a
depth of water of not less than 36ft. 6in. This brought
upon the caisson the enormous strain of not less
than 1,400 tons; and yet the deflection taken at the
middle and at a point where there were 76 feet clear
between the bearing surfaces was nearly -aths of an inch.
The ultimate resistance of which the caisson is capable,
according to Mr. Fairbairn's calculations, is fully 7,000
tons.

It has been generally admitted that Mr. Scamp's ar-
rangement of caisson is a very marked improvement,
and one which, from its simplicity of action, and the
quickness with which it can be worked, is likely to be
very extensively adopted.

SUNDAY CLOSING.
10 THE EDITORS OF THE LEEDS MERCURY.

Gentlemen,—lt may appear very right and natu-
ral in my old friend, the postmaster of Barnsley, and
the clerks in the Leeds post-office, to rejoice in
the apparent closing of post-offices on Sundays ;
but in common honesty they should have told
the whole truth; they should have let the public
know that although there is no sorting of letters on
that day, yet the bags are received, opened, and dis-
patched as usual, whether empty or not, while hun-
dreds, aud in some offices thousands-of letters remain
in the receiving box from Saturday night until
Monday morning. Thus a mass of incalculable riches
remains in every post-office untouched for two nights
and a day, at the very time a clerk or clerks
are necessarily engaged in their secret duty of di-
patching or receiving bags on the Sabbath-day ! As
for postmasters, their responsibilities and anxieties
are necessarily increased by having so long under
their care loads of communications so important to
society ; for it ought not to be forgotten that post-
offi,:es are not free from casualties.

Individually, no one would rejoice more sincerely
than myself in lessening labour on the Sabbath-
day ; but as we all know, or ought to know, there
are works of n.cessiry, and as intercourse with
the human family is an obvious every day duty,
I look upon the system which has exposed the
nation to the ridicule of the rest of the world as
positively presumptuous, insulting, and sinful, and
will be productive of more immorality by its hollow •
ness and hypocrisy than any measure that ever was
precipitated by well-meant ignorant zeal.
My old friend, and your other admirers, evidently
have not taken a very enlarged view of this vital ques-
tion, but are actuated by mere personal feelings. And
even in this respect I fear they are short-sighted, and
will only have their eyes opened when an intimation is
given (which is pretty certain) that their salaries
will be reduced one-seventh part ! Then the folly,
the hypocrisy, and absurdity will flare upon
them. Then will they be glad to return to the Post-
master-General's judicious arrangements, which,
while they kept alive the social and commercial ele-
ments, were not a whit more unscriptural than the
mischievous new system, which, if continued, will in -
flict many great social evils,* disarrange the commer-
cial intercourse, neutralise our boasted celerity of
transit, and ultimately cause the nation to retrogade
a whole century I
I am, Gentlemen, yours respectfully,
War. MOOSE.
Post-office, Huddersfield, Sunday evening,
June 30th.

* Most remarkable—while conversing this evoning on
this subject with Mr. Micklethwaite, tht• Huddersfield
Chronicle, a milkman, with his ass and cans, passes by,
and several carriages from church; a rap is heard at the
door; the railway porter with a parcel; my friend opens
the parcel and exclaims, " Good Godl my mother is
dead!"