156 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[May, 



historical, and converted into so many "scenes." Pictures in frames 

 do not force themselves importunately upon our attention: while 

 they contribute to general embellishment, they do not insist upon 

 being looked at; but we may do so or not according to the humour of the 

 moment. Few wou d relish dwelling in rooms where the same scene.be 

 it either solemn or the contrary, is constantly acted before their eyes. 

 However masterly the paintings themselves might be, they would soon 

 sicken of being shut up in a Miltonic "Paradise" or "Pandemonium," 

 or a Dantean " Inferno ;" while a perpetual Elysium would be likely 

 to inspire them with the blue devils. Nay it is not everv picture 

 that one would care to have hung up in a drawing-room or other 

 domestic apartment: the "Lazarus" of the National Gallery, for in- 

 stance, would not be particularly desirable or exbilirating as a com- 

 panion in such a place. It is all very well to talk about fresco-paint- 

 ing and the grand style of art; yet it does not follow that we are 

 bound to admit them into our houses. They neither suit us, nor do 

 we suit them ; which may be unlucky, but is nevertheless the case. 

 The truth is, we are a very matter-of-fact people, and live in a verv 

 matter-of-fact age ; nor will all the arguing in the world render us 

 otherwise, for we might as well attempt to change the natural atmos- 

 phere, as the moral one which surrounds us. It is verv easy to say, 

 let us revive this, or revive that ; but how are we to infuse actual life 

 and vitality into that which has been extinct long ago ? The utmost 

 we can do is to conjure up the mere ghost of it, and for ghosts the 

 world has now little relish. The king of Prussia is now endeavour- 

 ing to revive the Greek theatre and Greek drama in their pristine 

 purity ; and he will do so — but how ? — precisely after the manner in 

 which Eglintouu brought back again the age of chivalry, with its 

 pageants and tournaments. It would perhaps be wrong to say that 

 art in this country is not yet ripe enough for fresco painting, since it 

 is more likely to be too rotten. 



SUGGESTIONS FOR THE 



MORE EXTENSIVE EMPLOYMENT OF CONCRETE IN 



DISTRICTS WHICH DO NOT POSSESS ROCKS 



SUITABLE FOR BUILDING PURPOSES. 



It is now many years since our active neighbours, the French, un- 

 dertook on a very large scale, the manufacture of artificial hydraulic 

 limes, with a view principally to introduce them as an ingredient into 

 that species of concrete which they have termed beton. Following 

 U) the track of Berthier, Vicat, ami Treussart, our own countryman, 

 General Pasley, has long since endeavoured to arouse the attention 

 of landed proprietors, engineers, architects, builders and others, to 

 the method of forming artificial cement, by the mixture of chalk and 

 clay in certain proportions, which should vary according to the quali- 

 ties of these two ingredients. Hitherto, however, notwithstanding 

 the perfect success which has attended the manufacture in the neigh- 

 bourhood of Paris, where it is carried on at this day on the very 

 same principles as those which General Pasley first had the credit of 

 introducing to this country, nothing has yet been done by ourselves to 

 carry out the practical application of a process which is evidently 

 calculated to afford a very fine field for the employment of labour, the 

 exercise of skill and ingenuity, and the profitable investment of 

 capital. 



Under the general head of calcareous concretes may be classed all 

 those substances which are composed of fluid mortar mixed with 

 broken stones, gravel, pebbles, fragments of bricks and tiles, or such 

 other hard mineral substance as may be at hand. An ordinary con- 

 crete is that which is made from a common chalk or other lime stone 

 which does not possess the property of setting under water. On the 

 other hand, the quick setting limes, and those which possess hydraulic 

 properties, as the Barrow lime, the Aberthan, that of Lyme Regis, 

 and other places, as the lias formation, compose the species of con- 

 crete which is termed beton. Now it is known that all the limes 

 which have been mentioned, owe their hydraulic property principally 



to the presence of a small quantity of flay in intimate combination 

 with the lime. Hence it is that Roman cement, which is burnt from 

 an argillaceous limestone containing more clay than any of the before- 

 mentioned, and indeed more than any of the rocks properly called 

 limestones, forms in concrete a more perfect kind of beton than any 

 other. Conceiving an ordinary limestone to form a simple concrete, 

 and conceiving Roman cement to form a true bJton, all other kinds of 

 limestone may be considered capable of forming a mixture interme- 

 diate between simple concrete and true beton, according to the pro- 

 portion of argillaceous matter they contain. 



It is quite a mistake to suppose that the beton so much in use 

 throughout France, Holland, Italy, and other states on the continent, is 

 invariably composed of broken stones mixed with lime, &c Such 

 appears to be a mistake into which O. T. of Newcastle has fallen in 

 his paper on concrete, in the Journal of February last, since he ob- 

 serves " that beton differs from concrete in broken stone being used 

 instead of gravel, in the proportion of two of stone to one of lime or 

 pozzolana of Italy, &c." Now the truth is, that although broken or 

 angular stones are commonly used in the manufacture of beton, yet 

 gravel and pebbles are not unfrequently made use of; and the real and 

 true distinction between concrete and beton lies, as we have already 

 said, in the employment for the latter of a more or less hydraulic lime 

 instead of a lime made use of for ordinary mortar. 



Among the best of the hydraulic limes employed for the French 

 beton, may be mentioned that of Metz and that of Senonche near 

 Dreux. The hydraulic limes of Tournay in Flanders and of Viviers 

 upon the Rhine, are also of excellent quality. The hydraulic limes 

 manufactured in the neighbourhood of Paris are composed of three 

 parts of chalk ground into powder, and made up into paste with two 

 parts of plastic clay. This mixture is formed into cakes, burnt in a 

 kiln, and then ground to powder. 



Application of Concrete to building purposes. 



The Romans extensively employed concrete not only in building 

 walls of every desciiption, but even constructed vaults and arches 

 entirely of this substance. Examples of this are found in the re- 

 mains of their baths, their theatres and temples. The arches in the 

 Coliseum, in the baths of Caracalla, in the temples of Peace, of Mi- 

 nerva, and of Venus, are mostly of concrete with an occasional rib 

 of brickwork. 



The spherical vault of the Pantheon at Rome, which is 133 Roman 

 feet in diameter, and also a great vault at the baths of Dioclesian 74 

 feet iu diameter, were both built of concrete, and their condition is as 

 perfect at this day in point of stability as when they were first 

 erected. A more modern example exists in the great concrete vault 

 for the dome of *t. Peter's, which is S2 Roman feet in diameter, and 

 144 iu height. While admitting that the excellent preservation of 

 manv Roman walls in Italy, Spain, and the south of France, clearly 

 proves the almost imperishable nature of the concrete or beton of 

 which they are composed, it has been objected by many modem archi- 

 tects, that the variable climate of Great Britain is unfavourable to the 

 duration of concrete in exposed situations, and the opponents of con- 

 crete have not hesitated to affirm that, if those Roman monuments, 

 whose preservation we so much admire, had been tested beneath a 

 more changeable sky, and exposed to the rigors of a more northern 

 ciime, they would have furnished far different evidence, that is, far 

 less favourable evidence of the value of concrete for building pur- 

 poses. In replv to this, however, it will be sufficient to adduce nu- 

 merous old castles which were built in this country soon after the 

 Norman conquest, aud whose walls, consisting of irregular masonry, 

 which bears a close resemblance to beton, are found at this day in a 

 state of excellent preservation. The gre.it Pictish wall, which is well 

 known to have been executed by the Romans, is also a striking in- 

 stance of the durability of well cumposed betoa; and upon the whole 

 we are justified in concluding from ancient remains existing in our 

 own country, that where good hydraulic lime is employed, beton will 

 last even in the atmosphere of Great Britain, for at least as many 

 centuries as most of the stones at present employed for building pur- 



