iChap. #. Of.MANCHESTER. 33 the town appear to have been built upon layers of large pebbles laid upoi* a bed of blue^elay four or five yards in depth 6 . And the iamq fort of foundations remained very common in the kingdom, for toany centuries afterward, the old ftce^le of the church at Prees in Shrop&ire ttfijig very, lately found to be reared upon a cpurfe of boulders and clay immediately above the natural rock. But the wall of the Roman Mancunium was not founded uni- formly upon the fame fort. of clayey cement. The foundation of the weftern valhim mos laid on two beds of blue well-worked clay, the lower being nea ly a foot in depth and remarkably ftiff and folid. But the foundation 6f the ibuthern was laid in two courfes* not of actual clay, bat of clay-mortar, clay and fand incorporated .together, and both lying upon a deep bed of fiite-rivcr-fand that ftill netainfed a little of its original moifture. Attd:a& cteytthottzf actually remained in ufe among us at Man* t:hfefter withiia thefe thirty or* forty years, fb : the neighbouring trhurch of Prefton was difcovered in 1769 to have been con- structed upon a layer of loofe paving-ftones laid in fand, * y The old materials of the Britifli banks the Britifh cabins aiid thi Britiih hovels itiuft* have fupplied the Romans fufficiently with flbnes. Anfi with thefe they constructed the high ftrong wall of their caftrumj'hetfpingthein together in a very irregular manner, and only Hoping the-fece of the- rampart a little. And as the wall was : gradually raifed frdni the breadth of feven or eight feet ai thebaje, ' and was narrbwed tx> dfie' or two at the creft, they co- ^ioufly poured their bailing ih6rtar upon it. This from its flu* idity'S^fiuafeditfelfirito the marly' openings and hollows of the vforkj 4hd from its flrength ' boifnd • all the* Irregular pieces "of ftone into a felld compared wall. And the whole cdurfe of the vallti& %oft hkye beeng^acefull^ terminated, wlt^ the Urie of. a plat&rfia 1 within and with a corqn?^ of battlements a!)ove ?. ' - irf l/ tfi£ ] fbritration of the' Rdhiiiri mortar,* the fand appears to have been 'mingled with the lime unrefined by the neve, and charged with all its loofe gravel and large pebbles. Some of the mortar appeared a&ually on breaking to Have' been mingled with pounded brick, the finall fragments of brick very prettily F chequering
