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thumb|The South Shields collier brig Mary, painted by John Scott in 1855, showing two views of the same vessel. A [[Bentinck boom is fitted to the foot of the fore-course as a labour saving device when tacking.]] thumb|A small trading brig entering the River Avon, Bristol|Bristol Avon, painted by Joseph Walter A brig is a type of sailing vessel defined by its rig: two masts which are both square-rigged. Brigs originated in the second half of the 18th century and were a common type of smaller merchant vessel or warship from then until the latter part of the 19th century. In commercial use, they