The Sun.
London, England, 1834-12-25 00:00:00

THE LATE DUKE OF GLOUCESTER.

The following is the reply of her Royal Highness the
Duchess of Gloucester to an addres of condolence from the
inhabitants of Cheltenham :
" Bagshot Park, Dec. 15, 1834.
" Gentlemen,—l thank you for your kind and affectionate
address. The justice you have done to the memory of the
Duke of Gloucester, and the sympathy you have expressed
with my affliction, have touched me to the heart.
" You, to whom his piety, his charity, his benificence, and
his illustrious example of the observance of every duty were so
well known, can duly estimate the loss sustained by his family,
his friends, and his country.
" Be assured, gentlemen, that the feelings you have thus
communicated to me, as well as my recollection of the regard
which the Duke of Gloucester entertained for the inhabitants
of Cheltenham, must ever lead me to take a deep interest in
the prosperity of that place.
( Signed) " MARY."

CLIFTON BRIDGE.

TO MR. THOMAS MOTLEY.

DEAR Sia,—Your projected bridge, in its more perfect
form, I have again examined with great pleasure, and with in-
creased conviction of its fitness for the singular position which
it is intended to occupy.
Considered in relation to its mechanical principle, and its
sustaining power, the arch you propose to construct is most
satisfactory, and will, I am persuaded, combine in a higher
degree than has ever yet been effected elegance, lightness,
stability, and magnitude of span. Nothing can be more con-
clusive with respect to its mechanical character than the con-
venient and economical fact, that it will be erected securely
without centering, and that the approximating halves will not
depend in any material degree for their own support, or for the
support of any load which may be placed upon them, on any
resistance at the vertex. Every portion of each half of the
bridge becomes as it is inished a bent lever, and the whole of
such half, consequently, may have its power determined, by
considering it as a series of such levers, or as one very extended
lever, of which the line of abutment is the shorter extremity.
It is obvious, however, when the lines of pressure are traced,
that It 7 this particular arrangement traction to a considerable
extent occurs, that, therefore, the diagonal braces occu-
pying the parts of an 0ru,...°7 bridge, for the purpose of resist-
ing; the thrust of the upper portion; 4- the arch by their weight
alone, afford essential support without '11.7 the arch at all.
In this application of the solid sides of the spac,.! 44 be crossed
is to be found, I apprehend, one material principle upon cn,....'h
the extraordinary lightness of your mode of construction
depends.
The most accurate attention which I have been able to di-
rect to the examination of your intended bridge, has not
enabled me to discover any well-grounded objections to it;
and, assuming the sufficiency of the abutments, both for thrust
and traction, the adequacy, by trial or calculation, of the sub-
stance of every part and of their junctions, and the excellence
of the strong, tenacious, elastic material which you propose to
employ, the firmness and security of the fabric cannot be
disputed. With these views of the essential qualities of the
arch, and my admiration of its appearance, as stretching across
the valley, at once beautiful and romantic, of the Avon, I
cannot but entertain a very ardent wish that they upon whom
rests the decision may be induced to adopt it. The structure
will, I am persuaded, do honour to the present advanced con-
dition of practical mechanics, and the taste of the influential
inhabitants of Clifton and Bristol, and will even prove orna-
mental to natural scenery of a description so splendid, as to
render almost endurable the ordinary ponderous productions
of art. That you may succeed is the belief, not less than the
wish of Your's most faithfully,
GEORGE BIRKBECK.
38, Finsbury-square, Dec. 16, 1834.
As it has been maintained that with an equal weight of iron
your arch is as strong as a chain bridge, it has been asked,
what would be the case if the weight were greater ? To this
it may be answered, that the strength would in the same pro-
portion be greater. Expansion and contraction would, of
course, in such a structure as has been proposed, take place to
a considerable extent, but without any damage, or even in-
convenience, provided the junction of the two halves of the
arch were effected with reference to this alteration.