Ratio of the Length and Height of Sea Waves. 109 



Art. XVI. — On the Ratio of the Length and Height of Sea 



Waves. 



By S. R. Deverell, Esq. 



[Read November 8th, 1877.] 



Of the phenomena appertaining to water-waves none seem 

 to have appeared more capricious to observers tHan the vari- 

 able proportion of the height to the length of waves. Indeed 

 such strange diversities are exhibited in this respect that 

 writers have used themselves to speak of different kinds of 

 waves as if they were of different species : — The short chop- 

 ping sea ; the steep high sea ; the long high sea ; the long 

 roU, of medium height and length — that measured tread of 

 old ocean, as an Arctic voyager has expressed it, which so 

 gladdens the eyes and the heart of the Polar sojourner when 

 he first strikes it ; finally, the tremendous " comber" of navi- 

 gators which from overhead threatens to bury the ship : 

 these are often referred to as originating rather from differ- 

 ent causes than as being so many transitions or attitudes of 

 the same thing or entity. There is, again, the mysterious 

 ground swell, which old seamen firmly believe to arise in 

 some occult manner from the bottom, proceeding in slow, 

 languid oscillations, but breaking with an everlasting roar 

 and violence on the shore to which it is bound. Mere mag- 

 nitude does not appear to be an essential characteristic of 

 any of these forms, for they may all be met with in various 

 degrees of size. Scoresby mentions waves in the Southern 

 Ocean a quarter of a mile from peak to peak; but this can be 

 by no means unusual, for in that vast sea, which may in truth 

 be said to be the native home of the great waves, five waves 

 to a mile is a very ordinary occurrence in a westerly gale, and 

 the writer has counted five to a mile when the waves have 

 not been more than six or seven feet high. The length of a 

 wave in fact is by no means a criterion of its height : its 

 actual magnitude is rather measurable by the area of a 

 vertical length-section than by the height. Again, as regards 

 the speed, the velocity, says Mr. Reed, seems to depend 

 almost entirely on the length of a wave and not at aU upon 

 the height. It should be remembered that existing know- 

 ledge on these subjects, to which general attention has only 



