Page:The Building News and Engineering Journal, Volume 22, 1872.djvu/125

 a Pian 9. 1872. THE BUILDING NEWS. AO) in conical heaps; of course the quality and hardness thus obtained will depend much on the nature of the clay. Perfect amalgamation of the materials with the cement is so well known to be necessary, that I should not allude to it, except from recollections in practice, where I found it so difficult to get workmen to doit. If the gravel is large, it will be advisable to add sand. Water in the mixing should be gradually poured on with the aid of a rose or divided jet, so as to prevent the wash of the cement. Treatment.—Proportions may vary from 1 of cement up to 7, 8, 9, or even 10 of other material for walling. Broken stones and flints do well and take less cement ; Marl- borough College Extension being 10 to 1 of cement. The name of the architect of those works is a guarantee that that proportion made good walling. For cores, lintels, and flats for landings, 4 or 5 to 1 of cement. Steps.—For the body of the step, 7 to 1, with 4 to 1 for the face—the 4 being usually pounded Portland stone. The cost of these steps is about one-half Portland stone. I would here mention a custom that prevails, to prevent my readers being deceived by appearances—it is the mixing of pounded marble with the cement, the effect being to give the steps very much the appearance of Portland stone. Where walls are more than fourinches thick they may be packed with rough stone, broken bricks, chalk, or any similar material, or almost any other material that can be easily procured in the neighbourhood. Advantages. —Cheapness (this, I would parenthetically remark, is, of course, enhanced where bricks and other building materials are not easily obtained), strength, durability, economy of space; its peculiar property of increasing in strength, unlike all other build- ing materials (this continuation extends, some state, to two years after erection) ; the uti- lisation of otherwise useless material. Mr. Blomfield, in his paper at the General Con- ference of Architects, stated it could be more rapidly constructed than brick, Herein I think he is in error, as the machine is only moved once a day, and thus only rises two feet per day, while [have often seena brick building rise a scaffold a day. Disadvantages.—Al architects of any ex- perience will have painfully fresh in their minds, the difficulty which, at some time or other, they have had to contend with of getting good mortar used. Will he not more often in the future have the difficulty pre- sented to him in a different form? Surely I may place foremost, then, the use of improper materials; not merely, as heretofore, the question of mortar, because we could see the bricks or stone, and know they were good; but now, in concrete buildings, the whole wall will require most careful minute by minute supervision to insure sound work. The wilful misuse by the workmen of good materials. Liability to fracture. I will not place under this heading the difficulty of treating concrete walls architecturally, be- cause I feel it will soon cease to exist. Our profession will soon agree with me, as I have recently said, ‘‘ And herein new forms will be created by the use of new materials, if only the desire be present not to be slavishly bound by precedent, but earnestly to strive to make the requirements of science express themselves in our works.” Apparatus.—It is of little consequence in the result, excepting, of course, as regards economy and rapidity of construction; the great point is the materials with which the walls are built ; if they are good our struc- ture is permanent, indeed, so much the case is this, that I have heard it cited as a disad- vantage against this kind of building, thus: ‘In this age of alterations, widenings of streets, and improvements, how stupid it is to build in a material that is so extremely difficult to take down.” I have not placed this amongst the disadvantages, because it must be, if anything, an advantage. The Wood versus the Iron Apparatus.—Shortly, the iron seems to do 2ft. in height against 1ft. Gin, of the wood. The iron is lighter, and consequently cheaper in carriage. ‘The point on which I feared, was the rusting of the iron apparatus, should the paint be rubbed off, or otherwise be removed, so as to expose the iron (the paint used, I may mention, is the Torbay oxide of iron). My fears have been quite dispelled, having seen some that has been in use six years, and has in parts no paint to cover, the iron not having the slightest appearance of rust. The reasoh, I am told, is that the Portland cement forms a coating; on this point I offer no opinion. It will be suffi- ciently close for estimating purposes to take the cost of hire of the iron apparatus at 6d. per cube yard of the walls. For the description of the machines in use, I would refer to the circulars of the makers, for they would be difficult of description without the aid of diagrams. Mr. Wonnacott, in his paper, suggests theimprovement of the present iron apparatus, the introduction of extending plates, permitting the lengthening of each plate 50 per cent. on the principle of the revolving shutters. I think his idea very good in theory, but am afraid it would be too complicated in practice. I consider that the apparatus at present in use is adapted for straight walling, but not so well adapted to bays or angle work (circular work I have not seen attempted), and that therefore some im- provements are advisable. Damp.—To test the absorbing properties relatively of this material and stock bricks, I asked Mr. Drake to make two bricks, one cast with matrix of rough gravel, and another faced up (as walls usually appear now when finished). I put them in water myself and append results :— Size. Stock Bricikievamevsticsci isc assiiecs asco Smooth-faced Concrete Bric cos ose Ordinary Cast Cement Brick ... ... ... 8} ala The increase after 24 hours’ immersion was :— Smooth-faced, 9oz ; the ordinary, 100z.; the stock brick, 1040z. I have not heard of this experiment being tried before ; the result is not so fayourableas Thad expected. Ithought that the cement would have absorbed less in proportion. Artistic Treatment.—This must be more in the future. First, be assured of the advan- tages of the material, and then, when we find it must be used, try earnestly to make it the vehicle for expression, unsaddled by prece- dent, as its novelty demands. Its treatment as imitation of stone, all will agree, is wrong. The material has a rough surface, and, un- fortunately, not an evenly-setting one, for the settlement of the material appears very uneven; so at present, at a cost of 7d. or 8d. a yard, it is all faced up, and presents thus a Portland cemented face. Surely this cannot be right. By the use of terra-cotta, by in- cised work, by, as has been suggested, coloured sand, by glazed ornamental uiles, sunk in to form stringings (but this mixture of glazed surfaces with the unglazed has its objections), surely we can develop an in- dividuality of treatment that shall commend itself. 1 shall next proceed to consider stone. Norp.—As Portland cement is the expen- sive ingredient of concrete, | may here men- tion in its favour that Mr. Bazalgette says :— «In many cases Portland cement would bear admixture with sand so as to enable it, to compete in price with common mortar, and secure greater strength in the work at the same expenditure.” B, E- ——— “RVATION oF Stonr.—Dr. Eugéne Robert, of Paris, recommends copper salts as being the best preservatives of stone in a damp climate. These salts prevent the formation of lichens, to the action of which M. Robert attributes the destruction of stone. ‘This is, without doubt, true for granite, but its efficiency for sandstone is questionable. The latter deteriorates by exfoliation, without the de- velopment of any vegetation.—Les Mondes. - DECORATIVE PROCESSES. COMPOSITION ORNAMENTS.—CLEANING AND REGILDING, By an Exprrrmxcep WoriMan. (Continued from page 88.) N our last we were speaking of the method of producing ornaments in relief on cabi- nets, in a similar style to those produced by the Chinese and the Japanese. In continuation, we may observe that the groundwork should be got up as smooth and level as possible, and in dead or flat colour ; black is the usual colour, but other colours may be used, great care being taken to keep the outline of the gold sharp and clean. The details of the figures and ornaments are now put in on the gold in the manner of an etching, and with as few lines as is consistent with a due definition of each part of the figure, drapery, landscape, or buildings represented. ‘The outlines may now be corrected, if required, by using the same black as that employed for the etch- ing, which should also be the same black as the groundwork, in order that the work shall have unity; the whole may now receive two or three coats of varnish. When we come to treat. of the inlaying of woods and marbles, we shall have more to say about the orna- mentation of cabinets, &e. We can scarcely leave the subject of gilding without speaking of composition ornaments, which are princi- pally used for the ornamentation of picture frames, window-cornices, &c., which have to be gilt. Compo., or composition orna- ment, is superseded for many purposes by papier-maché; but the decoration of picture-frames in imitation of carved work is done, as a rule, by composition ornaments, for which purpose the material is better suited than papier-maché or any other com- position, on account of the facilities its pliability gives to the workman for adapting it to the unequal surface of the moulded frame it is to ornament. The Italians seem to have been the original inventors of this method of ornamentation ; or if not the originators, they evidently prac- tised it long before its introduction into this country, and, in fact, they were the first to practise it in England fifty or sixty years ago, and for a considerable number of years subse- quently the greater part of the picture-frame and looking-glass trade was in the hands of Italians, and some of our most eminent firms of to-day are descendants of Italians who came over well on to a century ago, bringing the secrets of their art-craft with them, supplying a want, improving the taste and skill of the English workman, and spreading a knowledge of much that was true and beautiful in art. A very large trade was at one time carried on by these men in the manufacture of wood chimneypieces, some of them carved, but the majority decorated with composition ornaments. Many of them were of exquisite design : fruits, flowers, Cupids, and love-birds ; allegorical subjects taken from both the an- cient and modern poets; music, poetry, and the drama—were often illustrated with ad- mirable skill and purity of design and form, many examples remaining to the present day in the houses of the last century. The mirror, or looking-glass, frame of that day would often be made in the same workshop as the chim- neypiece, and in the same style, and thus har- mony in design was preserved. Looking at the real and undoubted merit of some of these old examples, the correctness of drawing and execution, and the graceful beauty of the designs, we have grave doubts of our boasted improvement—in the matter of chimneypieces, at all events. In the mixing of the composition for this purpose, most workmen who make it pretend to have some pet ingredient or secret for its manufacture different to others. This may or may not be the case, but it may be taken as arule that any mixture of ingredients, no matter what they may be or however simple, if they answer the purpose intended in an