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The imposition of such a heavy load on the compiratively green concrete of the walls called for considerablc care. Further, owing to the variable depth of the lilling under the jacking bases there was a strong tendency t o tilt, which had to be checked immediately. 'Some small cracks developed in the wall in one instance as a result of tilting, but they closed up immediately when the pressure was relieved.The tensile steel of the cross beams was pre-stressed by similar methods to those Fig. 25. ,,A\, Jacklng bare] Scale; 1' = 16 feet. SUBWAY-TYPICAL CROSS SECTION.mentioned in the Paper. The deflexion of the longest beam, which had a clear span of about 42 feet, was measured after it had been relieved of support from the stanchions in the east wall of the old subway and was found to be inappreciable. Tell-talea placed across the junction between these beams and the old brickwork show tbat no differential settlement has taken place since their construction. Although the condition of the arches was such that careful observations had to be made continuously throughout the work, the underpinning was carried out without mishap of any description. Discussion.Mr. E. J. Buckton introduced the Paper with the aid of a series of , lantern slides. He observed that it had been written and printed under difficult war conditions, and some of its shortcomings might be attributed to that fMt.

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