1911 Encyclopædia Britannica/Brace

BRACE (through the Fr. from the plural of the Lat. bracchium, the arm), a measure of length, being the distance between the extended arms. From the original meaning of “the two arms” comes that of something which secures, connects, tightens or strengthens, found in numerous uses of the word, as a carpenter’s tool with a crank handle and socket to hold a bit for boring; a beam of wood or metal used to strengthen any building or machine; the straps passing over the shoulders to support the trousers; the leathern thong which slides up and down the cord of a drum, and regulates the tension and the tone; a writing and printing sign ({) for uniting two or more lines of letterpress or music; a nautical term for a rope fastened to the yard for trimming the sails (cf. the corresponding French term bras de vergue). As meaning “a couple” or “pair” the term was first applied to dogs, probably from the leash by which they were coupled in coursing. In architecture “brace mould” is the term for two ressaunts or ogees united together like a brace in printing, sometimes with a small bead between them.