1911 Encyclopædia Britannica/Beaufort Scale

BEAUFORT SCALE, a series of numbers from 0 to 12 arranged by Admiral Sir Francis Beaufort (1774–1857) in 1805, to indicate the strength of the wind from a calm, force 0, to a hurricane, force 12, with sailing directions such as “5, smacks shorten sails” for coast purposes, and “royals, &c., ‘full and by’ ” for the open sea. An exhaustive report was made in 1906 by the Meteorological Office on the relation between the estimates of wind-force according to Beaufort’s scale and the velocities recorded by anemometers belonging to the office, from which the following table is taken:—

Beaufort scale.	Corresponding wind.	Limits of hourly velocity.
Numbers.		Miles per hour.
0	Calm	Under 2
1–3	Light breeze	2–12
4–5	Moderate wind	13–23
6–7	Strong wind	24–37
8–9	Gale	38–55
10–11	Storm	56–75
12	Hurricane	Above 75