Engineering Wonders of the World
Volume III

GREAT UNDERPINNING ACHIEVEMENTS. 313 ployed in securing a foundation for the cathedral. Beech had been selected for the purpose, and the trees were placed side by side horizontally, a second layer being in some cases ren- dered necessary owing to the loose character of the soil. Although seven hundred years had passed since these founda- tions were put in, many of the logs were sound Their Cause. . at heart. had seized others ; but even where they had become rotten, owing to the water contained in the subsoil, the timbers had not been squeezed or flattened out by the superincumbent weight. Underneath the logs was a bed of chalky marl, in certain places six feet thick. The peat bed seemed to be virtually im- pervious to water, but when the trial excavation had reached Diagram to show the work that had to be done by a diver under ths walls of Winchester Cathedral—namely, to cut a series of pits in the clay and peat down to the gravel stratum, and fill in with, concrete, bricks, and cement. about a foot from the bottom of the deposit —the thickness ranging from 5 feet to 8 feet 6 inches—a volume of water burst upwards through the lowest layer, having made its way from the gravel bed below, into which it had flowed from the river Itchin. Called upon to deal with a task which imperilled the very existence of the entire edifice, Mr. Jackson and Mr. Colson wisely summoned Mr. Francis Fox, of Sir Douglas Fox and Partners, to their aid. Every one could see that ordinary pumping operations would be futile, and it was equally certain that the use of compressed air could not be relied upon during the work of restoration. Screw piles and caissons were regarded as being also unsuitable, and resort to the expedient of constructing a slab of concrete under the cathedral was deemed undesirable. These but a diver could do save the fabric from an experienced man different methods were discussed in turn, and all alike were rejected. It seemed that none what was necessary to disaster. Mr. Walker, employed by Messrs. Siebe and Gorman, was therefore engaged Diver ° employed, to complete the necessary ex- cavation, which had to be made in water, and this he accomplished in lengths of five feet. An illustration shows the diver in the act of descending into fourteen feet of water. Mr. Fox, an expert diver himself, donned the dress and made a careful examination of the solid strata under the peat bed. He was satisfied that the hard flinty gravel, resting as it did upon the chalk measure, offered an excellent material upon which to insert the new foundation that was obviously needed.