In the beginning of the 19th century, sailors were describing wind forces instead of wind speeds, yet they lacks a uniform scale to estimate these forces.
His scale as well as the more precise wind speeds in Knots or sometimes in meters per second are now widely used.

Beaufort scale

Specification and speeds Equivalent speed at 10 m above sea level   Mean Limits Description in forecasts State of sea Probable height of waves* metres Force Description Specification for use at sea* knots metres per second knots metres per second * These columns are a guide to show roughly what may be expected in the open sea, remote from land. Figures in brackets indicate the probable maximum height of waves. In enclosed waters, or when near land with an offshore wind, wave heights will be smaller and the waves steeper.

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