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56 THE CIVIL ENGINEER AND ARCHITECT’S JOURNAL. [February 1,1S6S. times the strength. He did not see how this could be made out upon any fair method of comparing the two materials. Brickwork was not required to carry the scaffolding as a concrete wall was. Brick work did not set so speedily, but in no sense that was valuable to the architect was the one ten times stranger than the other. Again he did not think that the fact of flues being circular would tend to lessen smoke. The statement that the solidity of the concrete walls tended to deaden sound, was also liable to exception. It was a well known fact that hollow walls deadened-sound better than solid ones. It had been found that in prisons, the solidity of the walls enabled the pri soners in adjoining cells to communicate better with each other, than if the walls had been hollow. He thought that the power to increase the thickness of the wall by inches was a very great advantage. The ability to use common labour in place of skilled labour—falsely so called, for bricklaying as commonly practised, did not deserve to be called skilled labour—was another advantage. He should like to know what effect fire had on concrete walls. His (Mr. Blashill’s) opinion was. that the fire would burn the cement in the concrete, and that the wall would begin to crumble down. He was, however, very favourably impressed with Mr. Tail’s apparatus, and believed that in time the various difficulties to which he had referred, would bo over come. We must however look them in the face and endeavour to provide remedies for them. Nr. W. F. Potter strongly approved of concrete as a building mate rial, and denounced the idea that it would lead us into a sham style of architecture. The same objection applied to the Houses of Parliament, British Museum, and other stone buildings in London, which were simply brick erections besmeared with ashlar. He should, however, like to know the cost of Mr. Tail’s apparatus. A short time ago, he had occasion to plan somehouses at Wimbledon Junction, since erected, and left it optional with the builders to make out their estimates for either brickwork or concrete, and he was afterwards surprised to find the concrete estimates were higher in cost, owing as it was alleged, to the price of the apparatus. Mr. Potter agreed with Mr. Biashill in not recommending leaving the tubing in the walls as a substitute for water pipes. Mr. Tall said the apparatus was not made for each house, but for a hundred houses. The cost of every apparatus or machine was conside rable in the first instance. If it were intended only to build three or four houses, he would net advise the adoption of this method, but if twenty or thirty houses were to be built, the cost of the apparatus would be saved'in the first two houses. Mr. Biashill had said that in some places houses could be built cheaper than in concrete, but brick could only be got at a cheap rate in a clay country; and if clay were plentiful it could be made into concrete at less expense than into brick. The objection had been made that the apparatus was only fitted to con struct one particular class of house ; this was obviated by extra panels being prepared to increase the apparatus to any' additional length re quired. With reference to the manner in which concrete withstood the action of fire, ho could state that building ballast would stand it better than gravel; at the same time it was a mistake to suppose that the cement in the concrete would slaken; cement which had once set would never slaken; and concrete, of whatever material compounded, would be sure to stand the action of any fire likely' to be made in a dwelling house. In the event of any portion of the foundation being on bad ground, a building of concrete would not crack or sink, the strength of the wall adjoining being sufficient to bear the extra weight. Even if the earth were to be dug from under the foundation the adjoining por tion of the wall would support the part which had been undermined. As an illustration of the strength of concrete he might mention that some time ago he was building a house during stormy weather; a master bricklayer, who was also building in the neighbourhood, deri sively warned the workmen to keep clear of the concrete house, which, he said, was sure to be blown down. A tremendous gale of wind arose that evening which scattered the bricklayer’s building to fragments, but the concrete remained unharmed. A member remarked that Mr. Tall had mentioned in his first lecture that his great difficulty had been the tendency to crack which was occa sioned by the expansion of timber introduced into concrete buildings. There were, however, wood blocks introduced to support tho scaffolding and he desired to know how these blocks did not also crack tho building. Another member enquired Mr. Tail’s method of fixing stone stairs. Another observed that the great difficulty was to obtain certainty as to the proper admixture of concrete. He fancied this was the reason why the material had been so rigidly excluded from the metropolitan district. A clerk of works, to give constant superintendence, seemed absolutely necessary. Good concrete was a very good material, but bad concrete was worse than rubbish. Mr. Potter inquired what would be the result if the water froze in the concrete channels which were part of Mr. Tail’s plan—would the concrete burst ? A member referring to the capacity of concrete for retaining heat, said that he had seen it used in the foundation of a furnace, and that it stood very well. Mr. Tall explained that tho cases where timber had cracked were when the joints had been pointed up with Portland cement; common cement only should bo used for this purpose. The blocks which were inserted in the concrete were not of large size, being only one-and-half inch square, and if swollen by damp would not have sufficient power to crack the wall. Stone stairs were easily fixed, it being only' neces sary to put a print in the wall of the size required to receive the end of the stone. With reference to what had been said about the proper mixture of concrete, he said a foreman was necessary' in the erection of stone and brick houses, and it was just as necessary that there should be some responsible overseer to superintend the erection of concrete dwellings, and whoso duty’ it would be to see that the material was properly mixed. It did not require a very intelligent man, as the directions were very simple. At the houses now being built at Graves end, an ordinary’ carpenter was superintendent. Witli reference to the water pipes, ho was not strongly in favour of their being in the con crete, and only offered the plan as a suggestion. He w’ould, however, guarantee that the water would not percolate through. He bad known no instance of water freezing in such Pipes, and could not say what the result would be. The concrete roof was also simply’ a suggestion, but he would again guarantee them perfectly’ water-tight, provided they were only on cottages. Concrete floors were excellent, being fire proof and water-tight, and very suitable for basements; he would not put them in cheap cottages unless there was ballast on the ground. He had been asked to account for the honeycombed appearance of the cottages at East Sheen. This arose from the material not having been crushed fine enough; the work was equally strong and water-tight, but the appearance was not so pleasing. Mr. Bailey Denton, Jun. remarked that perhaps there was no class of constructions for which concrete was a more fit material than Agri cultural labourer’s cottages, and rural constructions generally. But he saw two great practical impediments in tho way of its adoption, accord ing to Mr. Tail’s method, highly ingenious though it was. The first is the cost of the apparatus employed. It is not often—unfortunately— that we meet with landowners who wish to build 20 or 30 cottages : and it appears that at least 4 or 5 dwellings must be built with Mr. Tail’s apparatus, in order to make it worth tho contractor’s while to buy it. It seems also that tho apparatus when bought, can only be employed in carrying out the special design for which it was first made. This is a great objection, for we invariably find that variety of design is pleasing, in cottage construction, as much as in any' other class of work. The second point is, the difficulty we shall encounter in getting men who will superintend the construction of the buildings. Workmen in the country are proverbially slow in adopting anything novel, and are careless to a degree, almost incredible. It appears that there is no material which requires greater care in mixing and laying than con crete, and he (Mr. Denton) would like to hear from Mr. Tall, what had been tho result of his experience, not in town, where skilled labour was abundant, but in the country, where intelligent workmen were the exception and not the rule. The President said, that it had struck him in visiting the buildings at East Sheen, that from the apparently porous nature of the mate rial, it would not be well able to withstand a driving south-west wind, and that even if a vertical wall could withstand the effects of the weather, it was very questionable if a roof of the same material could. With reference to the proper admixture of concrete, it had to be borne in mind that the proportions allowed of considerable latitude. Mr. Tall had told him that he was able to use one part of cement to twenty-five of Ballast. The usual proportion was one to eight. So long as it varied from one to eight to the proportion of one to twelve, the concrete was sure to be good. It was the workmen’s interests to mix the concrete properly', as the scaffolding depended on it, and their lives were endangered by badly mixed work. The great disadvantage in using concrete, however, was the difficulty of making alterations afterwards in the plan of building. Clients were constantly changing their minds, and some provisions must be made for [this propensity. With reference to applied decoration, it' seemed to him that it would always be necessary, except in cases where fine ballast was used, and the concrete was well and evenly mixed. An imitation of stone work was especially to be deprecated. Glazed tiles were also objectionable and painting was probably the best thing which could be done. Mr. Mathews said, that every material had its faults, and therefore concrete must not be expected to answer in every respect, and he did not consider that the objections raised against it were morethan would have been found with brick or stone. The chief difficulty was its non-adaptability to persons whojwant to build two or three houses only. Mr. Tall had said that his apparatus was not constructed for the few but for the many, but then what was to become of the few. If this diffi culty could be overcome, the material would be used to a greater extent than it is otherwise likely to be, and by the very people to whom a cheap mode of building is a desideratum, but who are at present prevented from making use of it.