The only London vault which I can find mentioned is one found exactly two hundred years since at St. Martin-in-the-Fields. A Minute of the Society of Antiquaries reads: “May 2, 1722: Mr. Stukely related that the Roman building in St. Martin’s Church was an arch built of Roman brick and at the bottom laid with a most strong cement of an unusual composition, of which he has got a lump. There was a square duct in each wall its whole length, of 9 in. breadth; there were several of these side by side: this building is below the springs on the gravel.” This building that was an arch, with its many flues, and cement floor—doubtless opus signinum—was obviously a Roman bath chamber, but probably it was quite small.
Fig. 5.
Evidence of the existence of fairly large vaults has been found at the Baths of Silchester, Wroxeter and Bath. These were all constructed in a most interesting and suggestive way of voussoirs made as hollow boxes in the tile material. Similar box voussoirs have been discovered at Chedworth and elsewhere.
Fig. 6.
Fig. 7.
Fig. 8.