1844. 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



119 



380 feet 

 510 feet 

 360 feet 

 346 feet 

 320 feet 



and foot races, for which it is exceedingly well adapted, but also 

 aquatic exhibitions and rowing matches, as the arena can be laid 

 completely under water in a very short time. A festival of this 

 last-mentioned kind was given on the occasion of the birth of the 

 King of Rome." 



To this account we need merely add that, notwithstanding there 

 are so few rows of seats, they are computed to be capable of accom- 

 modating no fewer than 30,000 spectators. We ought to observe, 

 however, that the dimensions stated by the writer whom we have 

 quoted, do not pretend to accuracy, we therefore give them according 

 to what we have found them stated to be in metres ; annexing, in 

 order to afford readier means of comparison, those of some ancient 

 ancient amphitheatres ; — 



Milan, Arena . • 780 



Rome, Colosseum . . 615 



Verona, Amphitheatre . 450 



Pola, do. . . 436 



Nismes, do. • . 400 



If we have spoken somewhat at length of this work of Canonica's, 

 we shall not do so in regard to any of his other buildings, and for a 

 most cogent reason, having, unfortunately, no materials for descrip- 

 tion ; and it has even now cost us no little trouble to ascertain the 

 names of those we here enumerate. Among those erected by him at 

 Milan are the Teatro Ri; the Teatro Carcano, and the Teatro Ftlo- 

 drammalico ; also the Casa Canonica his own mansion, and the Palazzo 

 Belloni. 



Canonica has been spoken of with high commendation by the writer 

 of an article in the Quarterly Review, on the " Palladian Architec- 

 ture of Italy," more especially with reference to the last-mentioned 

 structure, "the front of which," it is there said, "is, perhaps, for its 

 size, the most beautiful of any private building in Italy. It consists of 

 a rustic basement story, with a balustrade, on which rests a disengaged 

 colonnade of six fluted Ionic columns, with an unbroken entablature, 

 and above it another balustrade with statues." We also find him 

 mentioned as the architect of three other theatres, at Brescia, Mantua, 

 and Parma; at least the last was designed by him, though executed 

 by Bettoli. Canonica possessed a considerable fortune, and has made 

 some munificent bequests, leaving by his will 174,000fr. (about£7,000) 

 to the Primary Schools of Lombardy, and 87,000 fr. (about £3,70U) to 

 the Milan Academy of Fine Arts, the interest of which is to be devoted 

 annually to the education and support of some young artist — architect, 

 sculptor, or painter. 



though each column is computed to carry a weight of ten tons, and a 

 wall of the same guard-house, otherwise built, has settled a good 

 deal. 



Fig. 1. 



Hg.2. 



Fig. 3. 



FOUNDATIONS ON SAND. 



The subject of foundations on sand has latterly attracted a good 

 deal of attention here, and particularly on account of Mr. Perring's 

 discovery that many of the buildings in Egypt were built on such 

 foundations. At page 80 of this volume of the Journal it is said, 

 " It seems that the stony surface of the desert had been made level 

 by a layer of fine sand, and confined by a stone platform 14 ft. 6in. 

 wide and 2ft. 9in. thick, which supported the external casing, and the 

 pyramid (that of Dashhour) was built on upon the sand which is firm 

 and solid." Other examples of the same kind were met with by Mr. 

 Perring, and it seemed that the sand, when retained in its place could 

 be depended upon. We have, therefore, thought it would be interest- 

 ing, while public attention is directed to the subject, to notice what 

 has been done on this system in France. It seems to have been first 

 adopted, in 1822, by M. Devilliers, C.E., when employed on the canal 

 of St. Martin, where he used it extensively. It is to be observed, 

 however, that it is the only system employed in the Dutch colony of 

 Surinam, and was suggested long since by Captain Rosmy but not 

 applied. 



We have no account of M. Devilliers' works, and the process seems 

 to have remained in abeyance until 1830, when Captain Gauzence, of 

 the French Engineers, employed it for the support of the portico of 

 of the Guard-house of Mousserolles, at Bayonne. This plan is repre- 

 sented in Fig. 1, where A represents the front of the portico, B the 

 fayade of the guard-house, and C the sand foundation. 



The soil was a slippery greasy clay, extending to a considerable 

 depth, and it was at first proposed to lay down a platform of wood as a 

 biisis. Capt. Gauzence's suggestion however having been adopted, 

 the soil was dug out to about a yard below the substructure and filled 

 in with sand well rammed. On this were laid two courses of Ashlar 

 masonry, and then a course of dressed stone, forming the surbase. Be- 

 fore finishing the columns, one of them was laden with ten tons of lead 

 without any sensible etiect being produced. The structure was 

 finished in October, 1830, and no settlement has taken place since, 



The same plan has been successfully pursued in some of the fortifi- 

 cations of Bayonne, where buildings had to be placed on made ground. 



In 1836 a sand foundation, about 2Aft. thick, was employed, with 

 an equally satisfactory result, for the quay wall of a small harbour on 

 the coast of Brittany. 



For the construction of the artillery arsenal at Bayonne another plan 

 has been adopted. The soil is of the same greasy kind before de- 

 scribed, while it is quite impossible to use wooden piles, for not only 

 is wood very dear in the neighbourhood, but at high water a stratum 

 of water penetrates the soil, which rapidly rots wooden piles or plat- 

 forms. Colonel Durbach therefore proposed to employ what have 

 been termed piles of sand. The forge department is surrounded by 

 square piers united by a wall, and in fig. 2 we have a section of one of 

 the piers, the weight of which, and of the carpentry supported, is about 

 35 tons. 



The foundation piles are so arranged that each bears only two tons. 

 The process adopted was to drive into the ground an ordinary wooden 

 pile about 7 in. square and 62ft. long. This was then drawn out, and 

 the hole filled with sand. The surface was then levelled, the sand 

 well rammed in, and the masonry raised upon it. To draw the wooden 

 mould pile, an ordinary machine was used, to which a chain was 

 attached in the manner shown in fig. 3. 



In 1833 Colonel Durbacb's plan, with some modification, was em- 

 ployed by M. Mery, C.E., in the canal of St. Martin, at Paris, for the 

 construction of a lateral culvert, which passed through ground of bad 

 quality, in which a quantity of water was infiltrated. Instead of sand, 

 which would have been washed away, sand mortar was used, made by 

 mixing one seventh of hydraulic lime with six sevenths of sand, which 

 soon consolidated. 



With regard to the sand to be employed, it is recommended that it 

 should be moderately fine, of equal grain, and not earthy. It must be 

 moulded and rammed in layers of about Sin. or 9in. thick, which is 

 an important point. 



The theory of this process is not known, but it is supposed that the 

 pressure is equally distributed on the sides as well as on the base. 

 Some curious circumstances as to the pressure of sand are to be ob- 

 served in connexion with blasting, where it is found to produce the 

 most efficient tamping. 



