RECORD AND DISCUSSION OF THE DIRECTION AND FORCE OP THE WIND. 



The direction and force of the wind was recorded at the same hours as those 

 given in the preceding record of the observations for temperature, and are the same 

 at which all other meteorological observations were made. 



In the preface to the journal containing the original record, Captain McClintock 

 states — "The true direction of the wind is given throughout;" and "the force of 

 the wind is indicated according to the Beaufort scale of notation, to 12, see Ad- 

 miralty's Manual." Comparing the direction of the wind given in the fourth num- 

 ber of Meteorological Papers published by authority of the Board of Trade, 1860, 

 I find that for a part of the cruise the magnetic direction is given, which in Cap- 

 tain McClintock's record is already converted into " true," the magnetic variation 

 having been applied ; I have, therefore, added to the record of the wind the ob- 

 served variation of the needle to show the amount allowed for in the conversion of 

 the directions. The proper reduction of the winds requires a knowledge of the 

 velocity of the air corresponding to each number expressing the force according 

 to Beaufort's scale; this I have derived from the following table :— 



Denomination of wind- 



Calm 

 Light air 

 Gentle breeze . 

 Moderate breeze 

 Fresh breeze . 

 Strong breeze 

 Fresh gale 

 Strong gale 

 Storm 

 Tempest 

 Hurricane 



The relation of the tabular numbers of pressure and velocity is in accordance 

 with Smeaton's table, and also agrees with that following from Dr. Bernoulli's for- 

 mula. By simple proportion, or by means of a diagram, we obtain the following 

 velocity number corresponding to Beaufort's scale, or to a graduation from to 12. 



