Sir Francis Beaufort (1774-1857), as head hydrographer of the British Admiralty, led the development of the finest surveying and charting institution in the world. Some of his charts are still used today, some 200 years after their creation. He is most famous for his system of estimating and reporting wind speeds. The measurements are based on the Beaufort Force or Number, which is composed of the wind speed, a descriptive term, and the visible effects upon land objects and/or sea surfaces. A “0” on the Beaufort scale describes a wind speed of less than 1 knot and calm seas; a “12” describes hurricane conditions. The Beaufort system was originally based on the effect of various wind speeds on the amount of canvas that a fully-rigged nineteenth century frigate (warship) could carry.
The Beaufort Scale (BBC)