THE MECHANICS' MAGAZINE, MUSEUM, Register, Journal, AND GAZETTE, JANUARY 1st.--JUNE 25th, 1842. VOL. XXXVI. "To distinguish and present, as it were, in several columns, what is extant and already found, and what is defective and farther to be provided." BACON. LONDON: EDITED, PRINTED AND PUBLISHED, BY J. C. ROBERTSON, 1842. Transportation T I72 EDITED, PRINTED, AND PUBLISHED BY J. C. ROBERTSON, 166, FLEET STREET. Mechanics' Magazine, MUSEUM, REGISTER, JOURNAL, AND GAZETTE. No. 960.] SATURDAY, JANUARY 1, 1842. Edited, Printed and Published by J. C. Robertson, No. 166, Flect-street. [Price 3d. MR. GIBBS'S IMPROVED SYSTEM OF BRIDGE BUILDING. We have already given a brief notice (No. 958, p. 490) of this system of bridge building, in our abstract of Mr. Gibbs's specification of certain patented improvements in roads, railways, &c., among which that system is included; but justice to the skill and ingenuity by which it is distinguished, and the many important advantages which it offers, requires that we should lay a more detailed and fuller account of it before our readers. The master feature of this system is, that it combines in one, the best properties both of the common arc bridge, and the suspension bridge, without the worst of their respective drawbacks-the solidity and strength of the former without its 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 equilibrated, as to rest perpendicularly on its piers without any out-thrust what ever. The engravings on our front page exhibits an elevation and plan of an entire bridge constructed on this plan. The following description of the details we extract from Mr. Gibbs's specification. "A A are the piers; B B the arches, which may be made of hollow iron tubes or of solid timber; C C are the suspending or main chains, or inverted arch; D D is the roadway, which may be fixed to the suspending rods; E E, rods which connect the two arches together; F F are what I call thrusting braces, which commence at the lower part of each pier, and are united to the first series of suspending rods at the junction of the inverted arch C C. Another series of braces G G, called the suspending braces, commence at the top of each pier at the place where the arches C C, on each side of the pier are connected together. These braces are connected with the suspending rods E E, at their junction with the lower arch B B. After the first set of portions of the arches are combined together, a second set can be added, precisely on the same principle as before described, each end of the bridge terminating with a half arch, and counterbalanced and resting upon the piers III. It will be cLvious, however, that the succeeding portions of the arches as they recede from the pier will have to sus- "The proportions of the different parts of the weights and nature of the materials to be used, and the mode of combinating them together at the joints will vary according to the character of the structure, and must be left to the judgment and skill of the engineer employed in each case." PRACTICAL SUGGESTIONS FOR THE PRO- Sir,-Although I am very reluctant to obtrude my opinions on public notice, yet feeling most strongly the importance of the subject, and possessing the means, from experience, of affording information that may prove beneficial, I will hesitate no longer to offer, through the medium of your valuable columns, an explanation of the means I have long since adopted, with great advantage, to secure my premises and property from the calamity of fire. The frequent and awful conflagrations which have lately taken place, to the great injury both of public and private property, render it extremely desirable that some means should be taken to prevent a recurrence of them, if possible; and as the precautions about to be suggested have been attended with most beneficial results in my own establishment, I deem it proper to make them generally known, as I feel persuaded that many or most of the recent fires might have been arrested, if similar care had been taken. I am the proprietor of an establishment where a number of workmen are employed amongst timber, shavings, linen, tow, oils, and where various articles of a combustible nature are used. To prevent an accident by fire, I have established several precautions. One of these is, that under each work-bench, SUGGESTIONS FOR THE PROTECTION OF MANUFACTORIES FROM FIRE. throughout the premises, stands a pail of water, merely covered over with a loose wooden cover. Any workman whose bench is deficient of this at any time is liable to fine or censure; in fact, the order is peremptory, and is always obeyed (I think the plan should be adopted in Her Majesty's dock-yards.) On one occasion my premises were saved by this means. A large bag of tow caught fire, from a candle being placed too near it, in the presence of four persons, two of whom were paralyzed with fear; the others caught up their pails of water, and subdued it in a minute. Had this not effected the object, there is a fire-pump in the yard, which would have been in action in three minutes more for it is so constructed, that by merely screwing on a hose, or various lengths of hose, one person can pump, and another direct the hose. I consider this description of pump to be one of the most useful and desirable appendages to a large manufactory, nobleman's mansion, or public building, that can be imagined. All buildings require a pump of some kind; and wherever there is an opportunity of placing a pump outside the house or building, it should be of this construction. I have had my pump eleven years. The care generally taken has made it unnecessary to have recourse to it, except for common purposes, on my own premises; but the house of an eminent grocer, who lives within thirty yards of my premises, having caught fire in the basement story, where his carpenter, who had just left work, had been making packing-cases, my watchman, who is on duty every night, screwed on the hose, and breaking up the area grating, introduced it within less than five minutes after the alarm was given. In about ten minutes more, and before any other assistance arrived, the fire was so much subdued as to do very little damage, (401, covered the loss;) whereas the house being in a very populous neighbourhood, abounding in old buildings, there is no knowing to what extent the mischief might have gone, had the fire not been stopped. Another precautionary measure I take is this: I have six strong bags made of common Russia sheeting, 1 yard long, of a yard wide, with a strong tape run through the mouth of each, my name and address being stained outside. These bags are laid on a shelf in my countinghouse, with strict injunctions that they are never to be used for any other purpose whatsoever, except that for which they are intended, namely, that in case of fire on my own or adjoining premises, the account-books and papers, or small articles, shall be instantly thrown into them, and removed to a place of safety in the neighbourhood. It is impossible to express the satisfaction you feel on having taken a precaution like this; but what it is I know from actual experience. A very alarming fire took place next door to my premises, to the destruction of four houses. I was absent sixty miles from London at the time; and on a certain morning, at ten o'clock, was surprised by the appearance of my coachman, who had rode down express to inform me of what had occurred; or, rather, to say that "a great fire was raging when he left, and it was feared my premises could not be saved." My first inquiry was, if my resident clerk was on the premises? The messenger replied, "Yes; and several of the men.' My mind was then immediately set at rest, because I knew all the books and papers would be safe; and as the stock and premises were insured, no very serious loss could take place. I was thus enabled to return in quiet mind to London; where I found, as I expected, the books and papers all taken to my residence, in the neighbourhood, and not much damage done to the premises, though the adjoining four houses were burnt to the ground. At this time the fire-pump was not erected, or the whole might have been easily saved of this there is no doubt whatever. To solicitors, merchants, public companies, and, in short, every person possessing papers of consequence, this precaution, the cost of which will not exceed 20s., is invaluable. Your inestimably useful publication, to which I have had the pleasure of subscribing for many years, appears to me the proper medium of disseminating a knowledge of these facts; and if you do not think the article too long for publication, the insertion will be esteemed a favour by, Sir, Your humble servant, A MANUFACTURER. P.S.-The late Mr. Russel, of St. John's-street, Clerkenwell, made my pump, in 1830; but since his death, I |