The foundation is, by the vulgar, generally believed to be laid upon woolpacks, which opinion probably arose from a tax being laid upon every pack of wool, towards its construction. Mr. Stow is of opinion, that before the bridge was erected, they were obliged to turn the Thames into a large canal made for that purpose, which began at Battersea, and returned into the bed of the river at Rotherhithe; but this supposition has not the least foundation. Mr. Maitland justly observes, that the purchase of the ground through which this spacious water course was to run; the expence of digging and raising the banks of sufficient strength; and the prodigious expence of damming off the river above and below the intended bridge, would have amounted to treble the sum of erecting the bridge itself; and that the space of thirty-three years, which the bridge took up in building, is sufficient to destroy so wild a notion; since if the people concerned in erecting it had dry ground to build upon, it might have been finished in a tenth part of the time, and in a much more durable manner. The same gentleman observes, that having carefully surveyed the bridge in the year 1730, in company with Mr. Sparruck, the water carpenter thereof, he observed in many places where the stones were washed from the sterlings, the vast frames of piles, whereon the stone piers were founded. The exterior part of these piles were extremely large, and driven as close as art could effect, and on the top were laid long beams of timber of the thickness of ten inches, strongly bolted; whereon was placed the base of the stone piers, nine feet above the bed of the river, and three below the sterlings; and that on the outside of this foundation were driven the piles called the sterlings. Mr. Sparruck informed him, that he and the bridge-mason had frequently taken out of the lowermost layers of stones in the piers, several of the original stones, which had been laid in pitch instead of mortar; and that this occasioned their being of opinion, that all the outside stones of the piers, as high as the sterlings, were originally laid in the same matter, to prevent the waters damaging the work. This Mr. Maitland naturally supposes, was done at every tide of ebb, till the work was raised above the high water mark.