AND OTHER WATER WAVES 63 



On the Effective Length of Fetch of Strong Winds 

 on the North Atlantic Ocean 



The volume of charts illustrating the weather 

 in the North Atlantic from December 18, 1898, 

 to February 15, 1899,* provides detailed and reli- 

 able information as to the effective length of fetch 

 of winds in that ocean. The storms were of unusual 

 strength and persistence, so that the charts give us 

 maximum values. The positions and distances 

 stated below are measured from the charts. At 

 noon, January i, 1899, a west wind of force 7-8 

 of Beaufort's scale and upwards (I.e., in no place 

 less than a moderate gale) is shown to obtain from 

 N. 49, W. 40 to N. 49, W. 60, a distance of 

 I j3 geographical miles or rather more. But, 

 in order that the waves at the lee end should be 

 reinforced by those at the weather end of the strip, 

 time must be allowed for the travel of the waves. 

 Waves of about 8 seconds period would be preva- 

 lent in such winds, and we will consider their move- 

 ment. Their speed is 8X3= 24 knots, and even 

 when going as forced waves before the wind they 

 will only travel 576 geographical miles in 24 hours. 

 Now, an examination of the charts for Decem- 



1 Charts illustrating weather of the North Atlantic Ocean in 

 the winter of 1898-9, Met. Council, 1901. 



