Altitude of the Waves. 193 



seaworthy. At the same time the sun shone brilliantly, the 

 sky was clear and beautiful, and only here and there some 

 feathery clouds were to be seen. There was a curious sense 

 of dualism in this serenity of the sky, in contrast with the 

 fury and agitation of the waves. Gradually the wind chopped 

 round towards the east, which gave some hope that the gale 

 would abate, but, nevertheless, the ship was tossed about worse 

 than ever. 



The waves, like gigantic ridges, mounted, according to 

 measurement, to the height of from 30 to 35 feet above the 

 mean level of the sea, and occasioned that terrible rolling of 

 the ship, and those fearful lurches, which, once experienced, 

 are not readily forgotten. 



Hitherto the altitude of a wave has been generally measured 

 merely by the eye, so that the result depended too much on 

 the accuracy of individual observation to admit of its being 

 exactly ascertained j and it is for this reason that the state- 

 ments relative to the maximum height of the ocean wave 

 are so various that they cannot be considered reliable, for 

 whilst some observers estimate them to be from 60 to 7O feet, 

 others reckon them only at from 30 to 40 feet. 



On board the Novara the following method of admeasure- 

 ment was adopted: we first determined, by a chronometer, 

 the time that a wave takes to pass from one end of the ship 

 to the other, whereby the velocity of the progressive motion 

 of the wave could be calculated in relation to the ship's 

 course and speed, regard being had to the direction and 



