" It has been before observed, that the graves of seve ral ages and fashions, in strata, or layers of earth, one above another, particularly at the north side of Si l'aul's, manifestly slimed a great antiquity from the British and Homan times, by the means whereof the ground had been raised. But, upon searching for the natural ground be low these graves, the surveyor observed, that the foun dation of the old church stood upon a layer of close and hard pot earth ; and that the same ground which had borne so weighty a building, might reasonably be trusted again. I I owever, he had the curiosity to search farther, and accordingly dug wells in several places, and discerned this hard pot earth to be on the north side of the church-yard about six feet thick, and more, but thin ner and thinner towards the south, till it was, upon the declining of the hill, scared four feet. Still he searched lower, and found nothing but dry sand, mixed sometimes unequally, but loose, so that it would run through the fingers. He went on till he came to water and sand mixed with periwinkles and other sea shells : these were about the level of low water-mark. He continued boring till he came to hard beach ; and still under that, till he came to the natural hard clay, which lies under the city and country, and Thames also, far and wide." Wren's Parentalia, p. 283, 284, 285.
" The sand hill at Paul's, in the time of the Roman colony, was about twelve feet lower than it now is ; and the liner sand easier driving with the wind, lay upper most, and the hard coat of pot earth might be thus made ; for pot earth dissolved in water, and viewed by a micro scope, is but impalpable fine sand, which with the fire will vitrify ; and, of this earth upon the place, were those urns, sacrificing vessels, and other pottery wart, made, which, as before noted, were found here in great abundance, more especially towards the north cast of the ground.
'‘ In the progress of the works of the foundations, the surveyor met with one unexpected difficulty ; he began to lay the foundations from the west end, and had pro ceeded successfully through the dome to the cast end, where the brick earth bottom was yet very good ; but as he went on to the north east corner, which was the last, and where nothing was expected to interrupt, he fell, in prose cuting the design, upon a pit, where all the pot earth had been robbed by the potters of old time. Here were discovered quantities of urns, broken vessels, and pottery ware of divers sorts and shapes ; how far this pit extend ed northward, there was no occasion to examine ' • no ox skulls, horns of stags, and tusks of boars were found, to corroborate the accounts of Stow, Camden, and others, nor any foundations more eastward. If there was formerly any temple to Diana, he supposed it might have been with in the walls of the colony, and more to the south. It was
no little perplexity to fall into this pit at last. He wanted hut six or seven feet to complete the design, and this fell in the very angle north cast. He knew very well, that under the layer of pot earth, there was no other good ground to be found till he came to the low water mark of the Thames, at least forty feet lower. His artificers proposed to him to pile, which he refused, for though piles may last for ever, when always in water, (otherwise London bridge would fall,) yet if they are driven through dry sand, though sometimes moist, they will rot. His endeavours were to build for eternity. He therefore sunk a pit of about eighteen feet square, wharfing up the sand with timber, till he came forty feet lower into water and sea shells, where there was a firm sea beach, which con firmed what was before asserted, that the sea had been in ages past, where now Paul's is ; he bored through this beach till he came to the original clay ; being then satisfied, he began from the beach, a square pier of solid good masonry, ten feet square, till he came within fifteen feet of the present ground, then he turned a short arch underground to the former foundation, which was broken off by the untoward accident of the pit. Thus this north east coin of the quire stands very firm, and, no doubt, will stand. This narrative may be of use to others not to trust piles, unless always, and in all parts, wet; for almost ail sorts of timber under water will prove ever lasting, but wet and dry will soon perish. The same cannot be said of iron, for that will decay under water : but this has been observed, in taking out cramps from stone work, at least 400 years old, which were so bedded in mortar, that all air was perfectly excluded. The iron appeared as fresh as from the forge. Therefore in cramp ing of stones, no iron should lie within nine inches of air, if possible ; for the air is the menstruum that consumes all materials whatever. When there is a necessity to use iron for want of stones large enough, care is to be taken to exclude sufficiently the air from it. To men tion another caution of use to artificers ; some cornices of large projections, though the upper joints are as close fitted as good workmen can make them, yet in the melt ing of snow, the water will dribble through, and stain the cornice. The surveyor thus avoided this inconvenience ; he caused the masons so to work the stone next the joint, as to leave half a quarter of an inch rising on each side, that the water might sooner fall off, than soak to the joint ; and this he observed in the paving of the up per portico of the principal front of St Paul's ; besides that the joints are run with lead : and the same is done, wherever he was obliged to cover with stone only." Pp. 285, 286.