Mathematical tile

Mathematical tiles are tiles which were used extensively as a building material in the southeastern counties of England—especially East Sussex and Kent—in the 18th and early 19th centuries. They were laid on the exterior of timber-framed buildings as an alternative to brickwork, which their appearance closely resembled. A distinctive black variety with a glazed surface was used on many buildings in Brighton (now part of the city of Brighton and Hove) from about 1760 onwards, and is considered a characteristic feature of the town's early architecture. Although the brick tax (1784–1850) was formerly thought to have encouraged use of mathematical tiles, in fact the tiles were subject to the same tax.