A system of estimating and reporting wind speeds using a numerical scale ranging from 0 (calm) to 12 (hurricane). It was invented in the early nineteenth century by Admiral Beaufort of the British Navy and was originally based on the effects of various wind speeds on the amount of canvas that a full- rigged frigate of the period could carry. It has since been modified and modernized and in its present form for international meteorological use it equates 1) Beaufort force (or Beaufort number), 2) wind speed, 3) descriptive term, and 4) visible effects upon land objects or sea surface. One land adaptation is the NRM wind scale.