Mr. Cowper said, that he should be incliued to attribute the slips Mr. E. to the expansion of the clay, from the action of water. H e had re-Cowper* cently examined the retaining walls, on the London and Birmingham Railway, in the cutting near the Euston Square station, and had found they were, in several places, forced forwards, apparently by some action behind them. This action was irregular, for its effects appeared indiscriminately at the top, at the bottom, and in the middle of the retaining walls, which were built of brick, generally about 5 feet 6 inches thick at the bottom, and 2 feet 6 inches at the top, with a curved face. Wherever the wall had been removed, for the purpose of rebuilding it, the face of the clay behind appeared to stand quite straight, without any fissure. H e was therefore induced to think, that water descended to various depths, according to the degree of permeability of the clay, and as far as its action extended, expansion took place. If the whole mass had expanded, from having been exposed to the action of air, before the face was covered with brickwork, the entire wall would have been moved forward, which was not the case. racter of slips, he was induced to think, that the slopes were generally Pas'ey' too steep; 2 to 1 had been considered sufficient for almost all kinds of earth, although Sir Henry Parnell, in his Treatise on Roads, said, '' When it is necessary to make a deep cutting through a hill, the slopes of the banks should never be less, except in passing General Pasley said, that from his observation of the usual cha-Maj.-Gen. L Downloaded by [] on [12/09/16].
