64 WAVES OF THE SEA 



ber 3 ist and for January 2nd shows that on 

 neither day was there so long a strip of water 

 simultaneously subject to west wind of force 7-8 

 as on January ist. Therefore the apparent length 

 of fetch on that day never became effective. But 

 we see on comparing the chart of December 3 ist 

 with that of January ist that a strip of 550 geo- 

 graphical miles was continuously subject to west 

 wind of force 7-8 for 24 hours, and towards the 

 end of this period this was the effective length of 

 fetch of the wind for 8 -second waves, and for 

 any swifter waves which the force of the wind may 

 have been capable of producing. 



At noon on January 10, 1899, winds of Beaufort 

 force 7-8 with direction a little W. of N. prevailed 

 from N. 47, W. 46 to N. 48, W. 32, a distance 

 of 600 geographical miles. On the previous day 

 (January 9th) at noon the wind was blowing in the 

 same direction between the same two positions, 

 with a force of 9-12, so that for 24 hours there 

 were winds of constant direction, with a force vary- 

 ing from a moderate gale to a hurricane, simul- 

 taneously and continuously affecting the water over 

 a stretch of 600 geographical miles. Towards the 

 end of the period, therefore, there was an effective 

 length of fetch of wind of 600 geographical miles 

 for all waves of rather more than 8 seconds period. 



