When at length the ruins of Old St. Paul's had come down and the huge mass of wreckage been cleared away, working from the west the excavations for the new foundations were begun. The old cathedral had rested on a layer of loam, or "pot earth" or "brick earth," near the surface; and wells being sunk at various points to ascertain the depth of this, it was found that the loam, owing to the ground sloping towards the south, gradually diminished from a depth of six feet to four. Sinking further, they found sand so loose as to run through the fingers; next, freshwater shells and more sand, and continuing through hard beach or gravel, they reached at last the London clay.[58] At one point of the north-east corner, where the loam had been dug out, Wren was compelled to rest the foundations on the clay; and it seems almost a pity that this was not universally adopted, at whatever additional cost of time and labour, in preference to the loam. The building had not long been completed ere the great weight of the dome caused some of the piers to sink from an inch to more than two inches, and Edward Strong the younger had to repair cracks and fissures.[59] Dean Milman tells us that in his time the City authorities once contemplated a sewer on the south side; but the surveyor, Mr. R. Cockerell, remembering that the sand and shells underneath the loam would be in danger of oozing out, went in great haste to him, and on their joint representation the project was abandoned. The old cathedral was not due east and west, neither did it directly face Ludgate Hill. Owing to the lie of the land cleared away, both of these peculiarities were increased by the surveyor, and the axis of the New St. Paul's was swung some seven degrees further north than the Old. He thereby made the best of his somewhat cramped site, and avoided the foundations of the old walls. The excavations were not completed nor the site fully cleared and made ready until 1674. [Illustration: RELATIVE POSITION AND AREA OF THE GROUND-PLANS OF OLD AND NEW ST. PAUL'S. _Reproduced from Longman's "Three Cathedrals of St. Paul's."_]