The construction of Lombard and Gothic vaults (1911)
Porter, Arthur Kingsley, 1883-1933 · New Haven : Yale university press; [etc., etc.] · leaf 22
became necessary to employ a cerce (Fig. 10). Below this point, large stonesare used; above, so as not to overcharge the light centering, the courses are nar-row and light, although sometimes the stones resting on the wall rib and hencesupported by it in large part are heavier (Left hand bay. Fig.… … cby Fig. 8 ally, in Gothic vaults, that the courses, instead of being normal to the walls, tendto converge towards the central key-stone, as in Fig. 8. The purpose evidentlywas to incline the courses more, and to give each stone a firmer point of supporton the stone placed below it, thus relieving…
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