98 Ocean Waves. 



depth of front water. In thus arriving at the cause, appre- 

 hension of danger from the breaking of waves in deep water 

 is dispelled ; it being impossible, according to natural laws, 

 for deep, or what is now called blue water to break. There 

 is, hoAvever, a slight partial breakage from what may be 

 justly called practical causes. All the preceding inferences are 

 based on the supposition that the waves are of the same 

 size ; but from the variable nature of the wind this is not 

 the case. When a large wave (known by seamen as a 

 master wave) follows a smaller one, there is a deficiency of 

 front water ; which is, however, instantly made up from the 

 particles beneath. Now, however rapidly such adjustment 

 takes place, it occupies an appreciable amount of time ; con- 

 sequently, a trifling imperfection or vacuum in the shape of 

 the advancing wave takes place, and a correspondingly 

 slight breakage occurs ; so slight, however, on account of the 

 rapidity with which particles of water replace each other as 

 to amount to no more than a ridge of foam on the crest, 

 dangerous perhaps to a very small boat, but not to a large 

 one if well managed. These considerations should be an 

 assurance to those who, in the hour of peri], are obliged to 

 entrust themselves to the mercy of the waves ; as they point 

 out that a boat has a much greater chance of living in a 

 wild sea (always premising deep water) than fears might 

 suggest or has generally been supposed ; and, as a matter of 

 fact, the truth of the proposition has been borne out by 

 numbers of instances. As a rule, blue water is a guarantee 

 of safety. 



A more genei-al cause for the partial breakage or foam-ridge 

 of deep sea waves is the superior impetus which the particles 

 on the summit receive. The surface of the wave spreads 

 like a sail to catch the force of the wind. If, therefore, the 

 velocit}^ of the wave be less than that of the wind, the back 

 and summit particles in the instant of imparting the extra 

 impetus to those before, will be pushed out of their place 

 and so break slightly. When, however, the waves have 

 attained their maximum velocity in accordance with the 

 strength of the wind (10) the partial breakage due to this 

 cause will have declined. The general appearance, therefore, 

 of lines of foam or foam-ridges, familiarly termed by seamen 

 " Neptune's teeth," is a sign that the wind is increasing, or 

 that the magnitude of the waves tvill increase ; and their 

 general decline shows either that the wind has decreased or 

 the magnitude of the waves increased. 



