What is the X in X-mas?
to measure wind velocity, developed 1806 by Francis Beaufort (1774-1857), surveyor and hydrologist.
|Beaufort scale |
A scale for classifying the force of the wind, ranging from 0 (calm) to 12 (hurricane). A wind classified as 0 has a velocity of less than 1.6 km (1 mi) per hour; a wind classified as 12 has a velocity of over 119 km (74 mi) per hour. Other categories include light air, five levels of breeze, four levels of gale, and storm. The scale was devised in 1805 as a means of describing the effect of different wind velocities on ships at sea. It is named after an admiral in the British navy, Sir Francis Beaufort (1774-1857).
scale devised in 1805 by Comdr. (later Admiral and Knight Commander of the Bath) Francis Beaufort of the British Navy for observing and classifying wind force at sea. Originally based on the effect of the wind on a full-rigged man-of-war, in 1838 it became mandatory for log entries in all ships in the Royal Navy. Altered to include observations of the state of the sea and phenomena on land as criteria, it was adopted in 1874 by the International Meteorological Committee for international use in weather telegraphy.