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JANUARY 1st.--JUNE 25th, 1842.
"To distinguish and present, as it were, in several columns, what is extant and already found, and what
EDITED, PRINTED AND PUBLISHED, BY J. C. ROBERTSON,
MECHANICS' MAGAZINE OFFICE, 166, FLEET-STREET,
PRACTICAL SUGGESTIONS FOR THE PRO
TECTION OF MANUFACTORIES FROM
MR, GIBBS'S IMPROVED SYSTEM OF BRIDCE BUILDING, We have already given a brief notice they recede from the pier will have to sus(No. 958, p. 490) of this system of tain less weight than those nearer to the bridge building, in our abstract of Mr. pier, and may accordingly be made lighter, Gibbs's specification of certain patented commensurately with the load they will have improvements in roads, railways, &c.,
to sustain. As many of these arches as may among which that system is included;
be required to form the width of the bridge, but justice to the skill and ingenuity
may be connected together by suitable hori.
In by which it is distinguished, and the
zontal and diagonal rods and braces. many important advantages which it
some cases it may be of advantage to run the
two arches through each other, which will offers, requires that we should lay a
permit a greater curvature to be given to more detailed and fuller account of it the arches. before our readers.
“ The proportions of the different parts The master feature of this system is, of the weights and nature of the materials to that it combines in one, the best proper be used, and the mode of combinating them ties both of the common arc bridge, and together at the joints will vary according to the suspension bridge, without the worst of the character of the structure, and must be their respective drawbacks--the solidity left to the judgment and skill of the engiand strength of the former without its neer employed in each case." abutments, and the lightness of the latter without its land ties. If there be no fallacy in the principles of construction followed by Mr. Gibbs—and for ourselves we do not see any-it should follow, that if care be taken in adjusting the weight of the materials employed, a bridge built on this system will be so perfectly equi.
Sir,- Although I am very reluctant to librated,' as to rest perpendicularly on
obtrude my opinions on public notice, its piers without any oul-thrust what.
yet feeling most strongly the importance
of the subject, and possessing the means, The engravings on our front page ex
from experience, of affording informahibits an elevation and plan of an entire
tion that may prove beneficial, I will hebridge constructed on this plan. The
sitate no longer to offer, through the following description of the details we
medium of your valuable columns, an extract from Mr. Gibbs's specification.
explanation of the means I have long
since adopted, with great advantage, to “ A A are the piers; B B the arches, which may be made of hollow iron tubes or
secure my premises and property from of solid timber; C C are the suspending or
the calamity of fire. The frequent and main chains, or inverted arch ; D D is the
awful conflagrations which have lately roadway, which may be fixed to the suspend
taken place, to the great injury both of ing rods; E E, rods which connect the two
public and private property, render it arches together; F F are what I call thrust. extremely desirable that some means ing braces, which commence at the lower
should be taken to prevent a recurrence part of each pier, and are united to the first of them, if possible; and as the precauseries of suspending rods at the junction of tions about to be suggested have been the inverted arch C C. Another series of attended with most beneficial results in braces G G, called the suspending braces, my own establishment, I deem it proper commence at the top of each pier at the to make them generally known, as I feel place where the arches C C, on each side of
persuaded that many or most of the rethe pier are connected together. These
cent fires might have been arrested, if braces are connected with the suspending
similar care had been taken. rods E E, at their junction with the lower arch B B. After the first set of por
I am the proprietor of an establishtions of the arches are combined together, a
ment where a number of workmen are second set can be added, precisely on the
employed amongst timber, shavings, same principle as before described, each end linen, tow, oils, and where various arof the bridge terminating with a half arch,
cles of a combustible nature are used. and counterbalanced and resting npon the To prevent an accident by fire, I have piers II H. It will be obvious, however, established several precautions. One of that the succeeding portions of the arches as these is, that under each work-bench,