INTRODUCTION. 2J 



over present, notwithstanding its intestine motions, 

 an unbroken and glassy smoothness. Tlie playful 

 ripple which breaks the moon's ray into a thousand 

 sparkling diamonds, and the huge billows that rear 

 their curling and cresting summits to the sky, would 

 be ahke unknowm. If the direction of the breeze 

 were exactly horizontal, it is difficult to imagine how 

 the surface could be ruffled at all ; but doubtless the 

 wind exerts an irregular pressure obliquely upon the 

 water, a few particles of which are thus forced out of 

 their level above the surrounding ones : these afford 

 a surface, however slight, on which the air can act 

 directly, and the effect now goes on increasing every 

 moment, until, if the wind be of sufficient velocity, 

 the mightiest waves are produced * " For he com- 

 mandeth, and raiseth the stormy wind, which lifteth 

 up the waves thereof. They [the mariners] mount 

 up to the heaven, they go down again to the depths : 



* The perpendicular elevation of even the highest waves is, how- 

 ever, much overrated. Viewed from the deck of a vessel, the im- 

 mense undulating surface causes them to appear much higher than 

 they are ; while the ever-changing inclination of the vessel itself 

 produces a deception of the senses, which increases the exaggera- 

 tion. Experienced practical men have, however, made some obser- 

 vations, which show us their height. Taking their station in the 

 shrouds, they have proceeded higher and higher, until the summit 

 of the loftiest billow no longer intercepted the view of the horizon. 

 After watching for a sufficient length of time to verify the deduc- 

 tions, they descended, and measured the height of the point of sight 

 from the ship's water-line ; deducting half of this distance for the 

 lepres.'sion of the hollow below the level of the surface, the remain- 

 der gives the elevation of the highest wave. It is thus found that 

 waves do not usually exceed six feet in height, except when cross- 

 waves overrun each other ; and probably in no case do the very 

 loftiest rise above ten feet above the general level. 



