624 



PKESIDENTS ADDRESS. 



the table following, and on Plate xxxvi., data are given 

 illustrating the relation between these properties. It is 

 interesting to note that in the case of small waves the rate of 

 travel is much greater than that of the exciting wind. At first 

 glance this seems paradoxical, but on consideration it is seen that 

 the water forming the waves is practically stationary relative to 

 the wind which gives its impetus to each wave surface as it rises. 



Table showing Properties of Steady Waves. 



Data for Calculatiox of Properties of Waves. 



Length =20 x height. 



Wind velocity (miles per hour) -2 x height in feet. 



Fetch zz 2000 x length. 



Fetch in miles ^ 0-3788 x length in feet. 



Wave speed in miles =1-55 x Vlength in feet. 



Wave speed. 



Wave length. 



When watching waves beating on the ocean beach most people 

 have noticed that at more or less frequent intervals a wave con- 

 siderably larger than the others will occur. The steady waves 

 may be due to wind, while the larger ones of longer period may 



Frequency: 



