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On the Construction of Fire-proof Buildings." By Ignatius Bonomi, Architect.

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ONE great, and perhaps the principal cause of the destructiveness of fires in large buildings, is the want of arched surfaces of incombustible materials. This has been disastrously exemplified in the destruction of the choir of York Minster, where the roofs of the aisles, which are solidly arched with stone, suffered no injury; while the choir-roof, although much more raised above the action of the fire, has been entirely destroyed by it: and there is little doubt but that the whole roof of the church would have suffered the same fate, if its continuity had not been interrupted by the walls of the tower.

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The use of arched surfaces of solid materials cannot be too strongly recommended. In no part of our church-architecture is the skill of the contrivers so conspicuous, as in the art employed in the construction of the vaulting, in order to ༥༠ procure strength and reduce the lateral pressure, which they effected by a frame-work of stone, of sufficient depth, converging towards the points of support, and by filling in the intervals with thinner material. They thus imitated the structure of the vegetable leaf, in which the fibres centre upon the stem, as the ribs or frame-work of the arch on its support; at which point, also, the buttress meets the ribs, to counteract the lateral thrust..

In many instances, to render the construction lighter, surfaces of brick are used between the stone ribs; and, where extreme lightness is required, hollow pots (cylindrical within) of well-burnt clay, would prove an excellent substitute for bricks. The use of these was not unknown to the Romans, who also employed pumice; this porous material possessing the additional advantage, when combined with good cement, of rendering the arched surface one united petrification, opposing (in consequence of its firm union) little lateral pressure, comparatively, against the sustaining walls. do A very frequent occasion of fire is the frequent necessity for the repair of lead gutters, which requires the use of brazier the roof. This necessity would, in a great degree, be འ obviated by the adoption of gutters of cast iron, or of solid

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lead cast in troughs, and having spouts at proper intervals to earry off the water. The action of the sun upon gutters, which by expanding the metal, is the principal cause of their failure, might also be much diminished by a thin covering of stone or slate, sufficiently perforated for the percolation of water. This contrivance would also have the advantage of preventing the lodgment of snow, which is apt to freeze in the gutters and occasion the water to overflow, to the damage of the building, and particularly of the timbering of the roof.

Another cause of fire is, the use of roofs of timber, especially when connected with the roofs cf other buildings. In such cases the substitution of iron for wood would afford security'; and if, in the use of iron, care is taken to make the rise or pitch of the roof sufficient to prevent indirect strains, and to tie in the feet of the main supports or triangles, there can be no danger of failure, provided the strength of the iron is proportioned to the weight it has to carry. If, however, the building has an arched under-roof of solid materials, and care is taken to prevent the necessity of continual repairs to the lead-work, the danger of fire, even from a roof of timber,' is very considerably obviated. In adverting to the use of a substitute for wooden roofs, it may be proper to specify that in some instances the slated surface might be carried upon cross walls, supported by the arches and divisional works of the building.

In a paper written for the express purpose of recommending precautions against fire in the construction of public buildings, it will hardly be deemed foreign to the purpose to state the impropriety of collecting into one room great numbers of books, or works of art. Even if security is obtained against ́fire from without, there is always danger to be apprehended from the use of lights within; and one spark igniting might occasion the destruction of the whole contents. The present collocation of the libraries of the advocates and writers to the signet in Edinburgh presents a striking instance of this kind of risk.

The means which may be recommended for securing such 'valuable collections from destruction by fire, are, in the first place, to use incombustible materials in the construction boz ló 10

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On the Construction of Fire-proof Buildings.

of the buildings containing them; and, secondly, to subdivide these collections into suites of separate rooms, which may be connected by wide and high doors of metal, rendered ornamental by plates of bas-relief, made to open upon pivots, and poised with mechanical skill, so as to be easily moved. By these precautions, should a fire unfortunately destroy the contents of any one room, it might be prevented from extending to the adjoining apartments.

It is not here intended to enter further into the details of construction; or to refer to the use of arches upon cast-iron beams and sheets of metal, &c.: but it is desirable to explain, that an excellent surface for interior finishing may be obtained, by using (instead of lath and plaster) a lining of brick detached from the exterior walls. This not only affords a security against fire, but has the additional advantage of interposing a medium of air between the inner and outer walls, which, by its slow conducting power, will prevent the interior of the building from partaking of the variations of the outer atmosphere, and consequently, in cold weather, will avoid the pre cipitation of moisture on the inner walls. To conclude, the examples afforded us in the ancient buildings of our own country, and those of Rome, present to the architect's contemplation a source of study on the subject of solid vaulting, in which, however dissimilar the forms, he will discover the application of the same mathematical principles of construction, combining strength, lightness, and economy of material. Durham, March, 1829.

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On the Early History of the Steam-engine.

A PAPER on this subject, and particularly on the rival pretensions of France and Great Britain, published by M. Arago, in the "Annuaire du Bureau des Longitudes" for 1829, has excited more attention than might have been thought due to so hacknied a topic. The cause of that attention will, perhaps, be found in the preface by which the paper is introduced, and of which the following is a translation.

"The steam-engine has rendered such important services to

industry and navigation, that we cannot be astonished at the eagerness with which various nations have disputed the honour of the invention. Yet it will not be heard without surprise, that in England alone one hundred thousand copies of the works in which this historical question is discussed, have been sold within a very few years. Such striking success is due, I doubt not, principally to the lively interest which the steamengine must naturally excite in a country where it is met with at every step; but may we not suppose that self-love has had some share in producing this effect? Ask the member of the House of Lords, and the most simple artisan; the merchant whose speculations have led him into every region of the world, and the farmer who has never passed the borders of his own county; traverse the manufactories of Birmingham, Manchester, and Glasgow, and the humblest workroom of a cottage; every where you will hear that the first inventor of the steam engine was the Marquis of Worcester. Every where this name will be cited, and it will be followed by those of Savery, of Newcomen, of Beighton, of Watt, of Hornblower, of Woolf, &c. &c. Literary men, and those who cultivate the sciences have, in general, opinions no less decided. If you open the recent Encyclopædia of Dr. Rees, you will find this passage: The steam-engine follows next to the ship in the order of inventions, but in an English Encyclopædia it will take the lead, from the circumstance of its being wholly invented and brought into general use by our own countrymen.' And then, as if this were not sufficiently clear: The steam-engine has been invented by a small number of individuals, all of them Englishmen.'

"The celebrated Professor John Robison, of Edinburgh, is quite as positive. He says, 'the steam-engine was, beyond all doubt, first invented by the Marquis of Worcester, in the reign of Charles the Second.' Then, after having refuted by arguments, which I will examine, the pretensions of those French authors who affect to mix up the name of Papin with the history of the steam-engine, Robison declares, That he does not hesitate in giving the honour of the first and complete invention to the Marquis of Worcester.' A philosopher, not less illustrious for the profoundness of his knowledge, than for

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the vastness of his erudition, Dr. Thomas Young, has joined his imposing testimony to those I have quoted, According to him the Marquis of Worcester is the first inventor of the steamengine, the first who has used the pressure of vapour as a prime mover. In the rapid view which he takes of the ameliorations which this machine has successively undergone, no names appear but those of Englishmen. I could also cite the Professor of Mechanics at the Royal Institution, Mr. Milling ton; a distinguished member of the new University of Lon don, Dr. Lardner; the author of an esteemed Treatise on Mechanics, Mr. Nicholson, &c. &c.

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Decisions. so numerous, so positive, the just reputation of the works from which I have quoted them, would seem to exclude, the shadow of a doubt. When, therefore, at the desire of the pupils of the Polytechnic School, I attempted, some years since, to trace the chronological series of improvements in the steam-engine from its origin till our own time, I expected, I say it without equivocation, to have only English mechanics to cite. This was, however, a mistake.Our neighbours on the other side of the channel are not the sole, neither are they the first inventors of the steam-engine." tuaq 911 The last, paragraph of this preface will explain the reasons for the extraordinary notice which has been taken of the paper. It has been supposed that the dispute was as new to every body, as M. Arago describes it to have been a few years since, to him. But the fact is, that the dispute, if it may be so called, is as old as the steam-engine itself, and it has been kept constantly alive for the last hundred years, as every one acquainted with the works of Belidor, Bossut, Montgery, and many others on the continer continent and in England, must be fully aware. The first of these writers alludes to it in his "Architecture Hydraulique," published in 1725, and concludes thus: "A proof that the steam engine had its origin in England is obtained from the fact, that all the engines erected out of England have been the work of Englishmen.". After this testimony by a Frenchman, writing when the facts were fresh in the recollection of the scientific world, it is almost too much to charge all the English writers (one only excepted) with having sacrificed the truth to their national prejudices; and especially when this is coupled

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