32 THE OCEAN. 
is somewhat variable and irregular, always fainter 
than-the sea-breeze, and dependent on the proximity 
of niountains. The application of what has been 
already said of the causes of wind in general will 
readily be made to these particular cases, the air 
on the surface of the water being cooler during the 
day, and that on the mountains during the night. 
Either is a grateful alleviation of the oppressive 
sultriness of the climate. 
But for the winds, the surface of the sea would 
ever present, notwithstanding its intestine motions, 
an unbroken and glassy smoothness. The 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 alike unknown. If the direction of the breeze 
were exactly horizontal, it is difficult to imagine 
how the surface could be ruffled at all; but doubt- 
less 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 in- 
creasing every moment, until, if the wind be of suf. 
ficient velocity, the mightiest waves are produced.* 
* The perpendicular elevation of even the highest waves is, however, 
much overrated. Viewed from the deck of a vessel, the immense undu- 
lating 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 exaggeration. Experienced practical 
men have, however, made some observations, 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 
