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THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[March, 



mechanical, dry, and repulsive. Whether any of his brother archi- 

 tects will now side with Mr. Gwilt, remains to be seen ; but in my 

 own opinion they have very little cause to congratulate themselves 

 upon having a champion in their ranks, who would show his prowess 

 by hewing down, and putting hors cle combat, all the volunteers en- 

 gaged in the same cause. Much liberality I did not expect from Mr. 

 Gwilt, but I certainly did suppose that he would exercise a little more 

 discretion than he has done. I did not, for instance, imagine that he 

 would allow his antipathy to German architecture to prevail so far, as 

 to give no account of any of the numerous fine buildings erected in 

 that country during the last 30 years; and as not to applaud the zeal 

 -with which'architecture is there cultivated, if he could not say much 

 in favour of the taste displayed in it. Had he done so — and the same 

 ■with regard to other countries, those chapters of his work might have 

 been made to contain a great deal of quite fresh and valuable in- 

 formation. The reason assigned by him for not doing so, is a most 

 flimsy and childish one — perfectly ridiculous ; for according to that, 

 there ought to be no such thing as criticism on contemporary works 

 at all; nor ought any to have yet appeared relative to those of a Thor- 

 waldsen, a Cornelius, and other great living masters in their respective 

 arts. Besides, he might have executed that part of his lask very in- 

 voctntly, and without giving the slightest umbrage to any one, by ab- 

 staining altogether from criticism and comment, and confining him- 

 self to description and mere matter-of-fact information. At pre- 

 sent, his apology for passing over altogether what be was conscious 

 ■would naturally be looked for, sounds too much like the fox's — " the 

 grapes are sour." The real reason, there can be very little doubt, 

 was his inability to make the necessary research, and collect mate- 

 rials for that part of his work, wherefore he would have done well to 

 obtain assistance for it. Considering his avowed and unqualified dis- 

 like, or I might say, hatred of modern German architecture, it is not 

 very surprising that he should not have referred us to any of its chief 

 productions, lest the bare mention of them should be mistaken for 

 approbation. Yet neither does modern Italian receive better treat- 

 ment from him, for lie says nothing of what has been done in that coun- 

 try, within the present or even the last century, excepting the palace 

 at Caserta. There is not a syllable relative to such architects as 

 Calderari, Temanza,Selva, Piermarini, Cagnola, Niccolini, and a great 

 many others, whose works display quite as much ability and taste as 

 some of those which he most highly praises. Nay, though he ex- 

 presses so very high an opinion of modern French architecture ge- 

 nerally, it is only in general terms, without either describing any 

 thing of the kind, or showing it in a wood-cut. In fact, he has not 

 introduced any fresh subjects among his " illustrations ;" and of his 

 " more than 1000 pngravings on wood," the greater part are mere 

 diagrams, and the rest of very ordinary character. What will ulti- 

 mately be that of his " Encyclopaedia " itself, may easily be guessed, 

 for most assuredly it will not obtain a very flattering one either from 

 students of Gothic, or admirers of German architecture, both of 

 whom will not only be disappointed in it, but offended also, more par- 

 ticularly the former, since they are by no means likely to relish the 

 insolently sneering and contemptuous tone in which Mr. G. speaks of 

 the " literary idlers, especially at the universities," who amuse them- 

 selves with inquiring into the history of Gothic architecture; which 

 censure, we must suppose, extended by him also to such publications 

 as those by Parker, and Bloxam, their object being to aid, encourage, 

 and promote the study of it, not at the universities alone, but all over 

 the kingdom. But the popular current against which Mr. Gwilt 

 swims, may overwhelm both him and his book; therefore, his opinions 

 may do no great harm after all. What is chiefly to be regretted is, 

 that his " Encyclopsedia" is likely to stand for some time in the way 

 of any better publication of a similar nature, because, though there is 

 ample room for one, in one sense, the market for it is, or will be 

 thought to be, pre-occupied. 



I remain, 



Yours, &c, 



" A Literary Idler." 



OK THE STRENGTH OF BEAMS. 



Sir. — One of the greatest advantages which the practical man has 

 over the theoretical, is that of being able to discover any gnat error 

 in a design by mere inspection ; this facility in discovering serious 

 mistakes at a " coup d'ceil " is only acquired by men of great practical 

 skill and long experience, and is a faculty too frequently dearly bought 

 by many failures ; the practical man, in forming a design for a bridge 

 or any mechanical structure, seldom uses anything besides a scale 

 and pencil ; he rarely commits any great error, but also he is rarely 



exactly right ; on the contrary, certain data being given to the the- 

 oretical man, he enters into calculations mostly always long and in- 

 tricate, and forms his design according to the dimensions obtained 

 from his results; he frequently commits a mistake in his calculations, 

 omits the consideration of some modifying circumstances, and thus 

 his design is faulty, and frequently is only discovered to be bad wheo 

 the structure falls to pieces ; even then he will certainly lay the blame 

 on the builder, like a celebrated French engineer who, being told that 

 a large bridge built according to his design had given way on the 

 striking of the centering, would not believe it, saying, "Impossible, I 

 calculated its dimensions to the greatest nicety." 



The sensible engineer will combine theory and practice, and giving 

 to neither undue preponderance, will certainly, ceteris paribus, pro- 

 duce the most perfect design; he will neither trust too much to the 

 eye nor rely implicitly on his calculations, and thus he will avoid such 

 a serious error as that which I committed, in my answer to the ques- 

 tion on the strength of beams, proposed for solution by "Concrete," and 

 which appeared in your Journal of last month; if I had constructed 

 the result obtained by algebra and made a sketch of the beam corre- 

 sponding to that answer, in short, if I had followed the advice given 

 above of not trusting too much to your calculations, but correcting them 

 by the eye, I should at once have perceived my gross mistake, viz., 

 that of multiplying, instead of dividing, the momenta of the weights 

 by the internal leverage^ of any point, in order to find the counter- 

 balancing weight. 



By correcting the error myself, I shall prevent much useless discus- 

 sion and comment from your Argus-eyed readers; at the same time I 

 shall briefly explain what I conceive to be the real solution of the 

 question. I stated in my letter of last month, that the true and best 

 form to give to the beam is the parabolic ; this being however de- 

 duced from erroneous calculations, must be altered, and a result much 

 more simple and satisfactory will ensue by modifying ihe equations 

 in one or two steps, dividing, in place of multiplying, the momenta of 

 the weights by the lengths of the internal segments at any point be- 

 tween the supports, in order to find the equivalent weight there. For 

 the purpose of rendering my explanation more clear, and making the 

 action of the weights on a beam so circumstanced, more intelligible, 

 I add a sketch of the form it will assume before it attains the point 



v$h 



of fracture. N', M', M, N, is the beam resting on the supports M', M; 

 the distance between these is C times that of the points of support 

 fM', M,) from the extremities N", N, to which the equal weights 

 W , W, are applied, to find the best form of the beam between the 

 points of support. On first applying the weights, the part between 

 the supports cambers, as represented in the sketch by the dotted line, 

 acd assumes a circular form, becoming more flattened at the centre as 

 it approaches the point of fracture, and ultimately breaks at or about 

 the points c, c,. I am indebted to a friend, on whose accuracy I can 

 depend, for the account of the experiments from which this explantion 

 has been deduced; you will observe how precisely it agrees with 

 Concrete's statement of the points of fracture as deduced from his 

 own experiments ; I must here apologise to him for having cast a 

 doubt on their accuracy ; I could not account how the beams could give 

 way at these points; which more particularly made me suspect some 

 error, is his statement that the bar of iron broke in tito points. The 

 experiments I brought forward in support of my explanation in your 

 Journal of last month, were conducted on such a small scale that I am 

 not in the least astonished at the fact of the model yielding in the 

 centre. It appears from the above sketch how the beam may remain 

 in a very curved position without breaking; the leverage of the 

 weights decreasing as the beam approaches the point of fracture. In 

 the following investigation, I shall however omit the deflection of 

 the beam and its weight. What then is the weight which, placed at 

 any point (P) between the supports, will balance the two external 

 weights, and what is the effect of its strain at that point ? 

 From the principle of the lever, it is found equal to W. MN X 



