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tion, and may be sold for at least 25 per cent, of its first cost. But to return to the facts of the before-mentioned concrete house built at Maiden. The 15 yards of concrete cost £5 Os 2d, and will build 60 yards superficial of 9 inch work at a cost of Is 8d per yard super. Here the gravel being sufficiently small there was no need to stucco the outside. And in places where the gravel ballast or stone is not so fine, it may be crushed as small as required, by means of a crushing machine. But if we suppose the concrete to be so coarse as to require stucco, we must then add 6d per yard super. Yet when it is considered that concrete walls require only one coat of plaster on the inside, thus saving two coats, it certainly is not fair to add this 6d per yard for the outside stucco, but I will even give this advantage also, and cal culate the concrete wall at 2s 2d per yard super. I will now compare this with brickwork in the same locality. At Marden bricks cost from 45s to 50 per thousand making, the lowest cost of the bricks in one yard super of 9 inch wall is just 4s 6d. Labor for bricklayer will cost £2 per rod, and mortar £1 per rod, or together Is 4d per yard super, so that the brick walls cost 5s lOd per yard super, as compared with 2s 2d per yard super of concrete, if we reckon in the 6d for stucco; but making fair allowance for the saving in inside plastering, the cost of concrete per yard is Is 8d, considerably less than one-third the cost of brickwork. I have not here mentioned an exceptional place, but can give a list of at least 500 4 other places, some of them the largest towns in the Uuited Kingdom, equally favourable for concrete build ings, and with proper machinery some districts will be found even more favorable. And now that the Metropolitan Board has at last decided in favour of concrete buildings in the Metropolitan area, some hundreds of builders will soon prove, by practical experience, the truth of by assertions. Mr. Biashill stated that he was doing brickwork in the West of England at £7 10s per rod. This is indeed an exceptionally low price, but every one must admit that if labour is so cheap for making and laying the brickwork it must be yet cheaper for concrete, where no skilled labour is required, and if even the labour were not any cheaper the concrete work would be cheapest, for it must be cheaper to throw clay up in heaps to burn, then mix with cement and throw into the apparatus, than it is to make clay into bricks, then dry them and stack them for burning, and then lay them by skilled labour. Evidently concrete requires much less labour than brickwork. Also if coal is cheap for burning bricks it must be equally cheap to burn the clay into ballast. But 1 cannot leave Mr. Blashill’s assertion without stating, that a gentleman from the cheapest county in the West of England, was present at the time of the discussion ; this gentleman is one of the largest builders in the county and for many years has had a brickyard of his own, and made all his own bricks. He assured me (as many builders have done since) that it was not possible in any part of the West of England, to build houses in brick work at £7 10s per rod, and after hearing the discussion and examin ing the concrete houses at East Sheen, and other places, he paid me a large sum for the monopoly of my patent in his county. Mr. Blashill seemed to consider that gravel was the only favorable material for making concrete. But the fact is that gravel is about the least favourable material. Of course where gravel is plentiful and no other material is to had, concrete would be made of gravel, but if other materials, such as clinkers or slag from furnaces, forges, gas works, soap boilers, iron works or other manufactories, or brick burs, or quarry waste or other stone from quarries are obtainable, the gravel concrete will be found more expensive than a burnt clay concrete. If I were about to build in a locality where gravel and clay were equally accessible, I should not think of using one bit of gravel. The clay would be the cheapest because in burning it would provide sufficient of large lumps to pack into the walls, thus saving a large proportion of cement; it is also tougher, burnt clay having a chemical affinity for cement, being one of its component parts. Burnt clay ballast is also much lighter, on which account there is a saving of labour in mixing, in hauling up to the work, and in laying into the apparatus. Moreover, it may easily be cut with a chisel, or even with a saw, like Bath stone, although it will bear a much greater crushing weight than that material. I have forwarded a block of ballast concrete which has a moulding worked on it, that you may see it can be wrought like Bath stone. This will meet the president’s objection as to the difficulty of making alte rations in concrete work. On having it broken you will see what it is made of. Burnt ballast concrete will also stand fire much better than gravel concrete. Concrete made of crushed clinkers or slag will also stand fire. Some of the best and cheapest concrete work that has yet been done is in a district where there is neither gravel nor clay; the builder has merely to provide a proper machine to crush the stone with which the district abounds and he builds cheaper and better walls than can possibly be built in districts where gravel only is to be obtained. However, there can be no doubt that burnt ballast will be the most general material for concrete, for if there is clay enough to build seven-tenths of the wall constructions in the United •Kingdom in brick, there is also clay enough to build them in concrete. The president, and some other gentlemen, expressed great horror at stucco, saying that all shams were objectionable. A few days since I accompanied an architect to Ealing, where he wishes to erect a large concrete house. He also expressed a decided objection to “ sham fronts,” at the same time pointing out a large brick-built house as a specimen of good brickwork. I at once told him it was a sham, it was coloured over with red ochre and tuckpointed, and I may say, without fear of contradiction, that 75 per cent, of our brick-built houses are coloured with red or yellow ochre. Are not these all sham fronts ? On our return from Holland Park by Bayswater Road to the Marble Arch, I could not help noticing the houses and mansions with stuccoed fronts, and these are letting from £100 to £600 per year, and not small cottages merely. Are all the architects of these houses and also of the largest houses and best houses in the West End, and in our best squares, sham architects ? Many of these houses are built with the very best stock bricks. But there are good reasons for these being stuccoed. 1st. To keep out the damp; 2nd. To give a lighter, more cheerful, and more ornamental appearance. And many architects who have not excessive “sham front” prejudices consider it desirable to introduce artistic ornamentation at the cheapest rate without sacrificing durability, and also to represent stone at about half its cost. I maintain that a good Portland cement stucco front is superior to a stone front. I can point out many stucco fronts in a perfect state of preservation which were done long before the Houses of Parliament were built, but the stone front of the Houses of Par liament is decaying in scores of places, although the stone was selected at great cost by eminent architects and engineers. I will conclude by asking all who require further information to refer to my pamphlet and to the paper which I read before the Archi tectural Association. This letter has been delayed on account of waiting the decision of the Metropolitan Board. I have now the pleasure of stating that concrete buildings may now be erected on my system in the metropolitan area. Yours, &c., Fallstaff Yard, Kent Street, Joseph Tall. Southwark, S.E. CENTRAL RAIL LOCOMOTIVES. Professor Henry Morton. Dear Sir,—Will you allow me to correct a slight error ? My friend Mr. Coleman. Sellers is stated to have made the following remark, when speaking about the centre-rail engine for railroads :— 11 The person to whom Professor Morton alluded was Mr. Trautwine, the Engineer of the Panama Railroad, who advocated the use of this plan across the isthmus. The engines ■were built; but the engineer who succeeded him concluded to cut down the road, and use common engines.” The error con sists in this : That I never contemplated the use of such engines on that road, further than.as a temporary resort, while making the summit excavations ; and even that idea originated with the board of directors, who were determined to leave nothing un provided for that could expedite the work. I expressed to them the conviction that no such precaution was necessary ; but in asmuch as it would at least do no harm, the directors requested their [consulting engineer (Mr. Horatio Allen) and myself to witness some experiments with a large working model engine, prepared by Mr. George Escol Sellers, its inventor, and to re port upon the result. We did so, and our report was unquali fiedly favorable, and the engines were accordingly ordered. This ■was at about the middle of 1850. They were not used on the Panama road, simply because, as I had predicted, no necessity for them presented itself ; and my co-engineer and friend Col. Totten, who remained upon the road after I had resigned, em ployed them as common engines. A centre-rail engine had been patented in England in 1830 or 1831, by Errickson & Vignoles ; but Mr. Sellers’s engine combines self-acting means for adjusting the adhesion to suit both the grade and the load, with other peculiarities, which renders it so far superior to that of Errick son & Vignoles, that it must be regarded as essentially a new and original invention. About thirteen years since, as engineer of the New York and Middle Coal Field Railroad, I recom mended the use of the Sellers engine on a grade of 150 feet per mile ; and the directors (the late City Postmaster, C. A. Wal- born, President), notwithstanding the unfavourable opinions universally expressed by other engineers, and by locomo tive builders, procured from Mr. Sellers two very powerful ones. Financial troubles, however, led to an abandonment of the road, and the engines were sold at very low prices to other coal com panies. As none of the officers of these companies understooed the principle or mode of action of the engines, they did not even make a trial of their capabilities, although it might have been done, and the grand problem satisfactorily demonstrated to all, for a few hundred dollars. As the worthy president of one of the companies himself complacently informed me, “We are all
