108 WAVES OF THE SEA 



case of the ordinary cup -anemometer the number 

 of revolutions recorded during " strong breeze," 

 " moderate gale," &c., had been compared with 

 those obtained by whirling the instrument on a 

 turn-table, by which means a counter air-current 

 of known velocity is produced. The earlier experi- 

 ments indicated that the number of revolutions of 

 the standard cup -anemometer must be multiplied 

 by three to give the velocity of the wind in statute 

 miles per hour. More complete experiments, 

 however, have shown that this " reduction factor " 

 was much too high, and the factor, or multiplier, 

 now adopted by meteorologists is 2.2. Hence the 

 velocities of wind found in records of some years 

 back are greatly in excess of the values now 

 adopted. Wherever the actual logged number ex- 

 pressing the sailor's estimate of the force of the 

 wind can be obtained, it is, however, easy to calcu- 

 late anew the velocity of the wind in statute miles 

 per hour, and this has been done in the present 

 book. Thus the velocities of wind quoted by me 

 as observed by Lieutenant Paris are not those 

 stated by him in metres per second, but those 

 recalculated from his logged numbers. The follow- 

 ing table is taken from a paper l by Mr. R. H. 



1 Q.y.R.M.S., Jan., 1897, vol. xxii., No. 101, pp. 24-55, 

 discussion on pp. 56-61. 



