13 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[April, 



so injudiciously formed, just at a time when the neighbourhood was 

 ripe for destruction, have only a fall of i inch in 20 feet, instead of a 

 fall of J inch to every foot which the commissioners profess to require, 

 these sewers are, therefore, only so many gigantic cesspools, from 

 whence noxious gases continually emanate. 



The natural boundaries of the district for improvement resolve 

 themselves into a square, of which St. James's Park is the base, 

 King's-scholars'-pond-sewer and Loiig-ditch-sewer the sides. It fol- 

 lows, therefore, that the sewers in streets parallel to this base must 

 have a much better fall, from a given summit level, than the sewer of 

 a street approaching the hypotbenuse, sucli as that now proposed by 

 certain projestors, which sewer, if raised so as to give a proper fall, 

 will be something like the embankment of a railway across the dis- 

 trict, and if not so raised, why then the evils of deficient drainage, of 

 which we have so long complained, aud which we hoped soon to see 

 remedied, are rendered permanent. 



The true principles on which the improvement of Westminster 

 should be conducted are — 1st. A thorough, systematic, and provident 

 application of the best medical and physical science to the architec- 

 ture, drainage, and sewerage; to tins end, the whole district must be 

 gradually treated in the same manner that Mr. Cubitt is treating a 

 similar district in the vicinity; the streets must all be raised so as to 

 admit of an habitable basement iioor to the houses, which modern 

 usage, habits, and the necessity arising from the increasing value of 

 ground demands. 2nd. To provide the most direct and convenient 

 road (without intruding upou the Park), for carriages, carts, and vehi- 

 cles of every description between Westminster Bridge and Grosvenor 

 Place. Srd. To open the most advantageous views of the Palace, the 

 Abbey, and the great Victoria Tower; this involves commodious 

 approaches to these national structures. 4th. To provide sites for the 

 erection of improved, healthful, and appropriate dwellings for the 

 poor. 



There are many minor principles which in carrying out the plan it 

 will be necessary to enforce, but which it is not at present requisite to 

 enumerate, and by a well digested plan, now before a committee ap- 

 pointed at a public meeting of the inhabitants of Westminster, it is 

 estimated that all these advantages may be attained without any ulti- 

 mate loss of the public money; an advance of money would be re- 

 quired, which would be returned into the Treasury, most probably 

 with a large profit, as the improvement of street after street was being 

 accomplished. 



These are nearly the principles which guided his late majesty King 

 George the Fourth in his design for the improvement of Westminster, 

 and had not old age so suddenly overtaken this magnificently-minded 

 monarch, there is little doubt but that the execution of his plan would 

 long since have been accomplished. 



The fully carrying out a similar plan in Westminster would render 

 any ministry popular, both with the crown and people, as an improve- 

 ment worthy the present enlightened times, in which we are, day by 

 day, more and more developing the power of mind over matter, and 

 reahzing that remarkable prophecy of Lord Bacon — " I have held up 

 a light in the obscurity of philosophy which will be seen centuries 

 after I am dead ; it will be seen amongst the best legacies of princes 

 to their people, in the erection of temples, tombs, palaces, theatres, 

 bridges, making noble roads, cutting canals, granting a multitude of 

 charters and liberties for comfort of decayed companies and corpora- 

 tions ; in the foundation of colleges and lectures for learning and the 

 education of youth, foundations and institutions of orders and frater- 

 nities for nobility, enterprize, and obedience; but above all the estab- 

 lishing good laws for the regulation of the kingdom, aud as an example 

 to the world." 



William Bardwell. 



Park Stmt. 



FIRE-PROOF BUILDINGS. 



Sir, — Will any of your kind correspondents favour me with an ex- 

 planation of what constitutes a fire-proof building / 



My own humble opinion is, that a fire-proof building, or a building 

 made proof against fire, should be that within which, if a fire take 

 place, the goods or furniture therein may be entirely consumed without 

 in any way injuring the main structure. 



Can any building in London be pointed out as such, — and why called 

 fire-proof? State the materials and mode of construction. It is ge- 

 nerally understood that there is no building in London built upon any 

 defined principle, so as as to be considered thoroughly fire-proof. 



Korthnmhrlan^, 



NOTE ON THE CAUSES OF EXPLOSION IN TUBULAR 

 BOILERS. 



The following brief explanation of a matter of great interest and 

 importance will, I think, be acceptable to many of your readers at the 

 present time. 



The cause of explosion in tubular steam-boilers is usually the ex- 

 ceedingly rapid generation of steam arising from overheating the 

 tubes. The due explanation of the effect will be found in considera- 

 tions frequently overlooked. In discussing the effects of the motive 

 power of steam engines, attention is usually confined to the statical 

 pressure of the elastic vapour, irrespectively of dynamical operations. 

 The latter, however, powerfully affect the case, which may be conve- 

 niently explained by reference to a familiar illustration — the explosion 

 of a gun caused by a slight obstruction at the muzzle. It is well known 

 that if the muzzle of a gun be stopped by a piece of card fitting it 

 loosely, or by a small piece of dirt, the gun will frequently burst on 

 discharge ; and it seems at first anomalous that the elastic vapour of 

 the gunpowder does not rather overcome the slight resistance of the 

 card or dirt than the strong cohesion of the metal of the barrel. But 

 the explanation seems to be this. In a compressed vapour, in ordi- 

 nary cases, the elastic pressure is equal in every part. The consti- 

 tuent particles of the vapour speedily arrange themselves in such a 

 manner that an uniform density and an uniform expansive force is 

 established. But this mutual action of the particles, by which they 

 dispose themselves in a position of equilibrium, although exceedingly 

 rapid, is not absolutely instantaneous. It may be easily conceived, 

 that if the gas generated by the ignition of gunpowder be not allowed 

 free passage it will begin to accumulate in the neighbourhood of its 

 origin — namely, the breach of the guu; and the process may continue 

 till the cohesion of the metal is overcome by the increasing force of 

 the accumulated vapour. Even where no obstruction is offered to the 

 exit of the gas, it may be generated so rapidly that its own elastic 

 force will not disperse it quickly enough ; so that in this case also, 

 accumulation of gas and the consequent effects may be produced pre- 

 cisely as in the first case. This instance exactly illustrates the effect 

 of steam generated in very hot tubes. Even when the safety Talve is 

 free (and even whf n it is absolutely open), if the rapidity of genera- 

 tion of the vapour exceed the rapidity of dispersion, an accumulation 

 will ensue. If it be granted that the cause of explosion is the evolu- 

 tion of hydrogen, the mechanical action is still the same. The phe- 

 nomena are not affected by the nature of the vapour — whether those 

 of steam or ignited hydrogen — but simply by the rapidity with which 

 those vapours are evolved. In either case, the only remedy against 

 explosion is to maintain all the parts of the boiler as nearly as possible 

 at the same temperature. 



H. C. 



ON THE INTERIOR DECORATIONS OF THE ROYAL EXCHANGE. 



A paper read by Mr. DwrEE, before the Decoratloe Art Society. 



In my previous remarks upon the Decorations of the Royal Exchange, I 

 treated principally of the effects produced when viewed as specimens of in- 

 terior decoration— 1 briefly stated its various beauties and defects ; and the 

 discussiun which followed, perfectly coincided in tendency with the critical 

 notice I ventured to offer. From the extreme difficulty 1 experienced in ob- 

 taining admission to view the interior, the opinions which I then formed were 

 not of that satisfactory nature I could liave wished, not having had the op- 

 portunity of examining the work minutely ; although I applied to the prin- 

 cipal persons I was unsuccessful, and it was only by a nianct-uvre that I 

 succeeded. The Royal Exchange having been since opened to the public, I 

 have availed myself of the facilities thus ollered, to inspect the decoratious 

 more attentively, the result of which compels me to state that they do not 

 improve like a good picture upon acquaintance ; the opinions I had previously 

 formed were more confirmed at each visit. The decorations are of that order 

 which lessen in value to the spectator according to the extent of his investi- 

 gation. There is indeed such an abundance of ornament, so much prettiness, 

 so much surface, without depth, that there remains nothing to dwell upon, 

 all freshness of purpose is wanting, and i lieu of it appears a general frivo- 

 lity teeming with the tamest effects ; although not Vanting in variety, it 

 only amounts to a variety of an inferior class ; it betrays a similar mind 

 and hand throughout the wdiole work. 



Before entering into the principal or more important part of the present 

 notice, I wish to continue, by a few remarks, a portion of the first one. In 

 the description I gave of the frescoes, I stated that which was executed over 

 the southern entrance to have been injured by damp; the stams have not only 



