The Collaborative International Dictionary of English v.0.48:

Beaufort's scale \Beau"fort's scale`\ (Meteor.)
   A scale of wind force devised by Sir F. Beaufort, R. N., in
   1805, in which the force is indicated by numbers from 0 to
   12.
   [1913 Webster]

   Note: The full scale is as follows: -- 0, calm; 1, light air;
         2, light breeze; 3, gentle breeze; 4, moderate breeze;
         5, fresh breeze; 6, strong breeze; 7, moderate gale; 8,
         fresh gale; 9, strong gale; 10, whole gale; 11, storm;
         12, hurricane.
         [Webster 1913 Suppl.]