INTEODUCTION. 9 



very beautiful and instructive instance it is of that 

 unerring skill and wisdom witli which the wliole 

 constitution is ordered and kept in order, by Him, 

 who, with minute accuracy, "weigheth the moun- 

 tains in scales, and the hills in a balance."* 



The Ocean is never perfectly at rest : even be- 

 tween the tropics, in what are called the calm 

 latitudes, where the impatient seaman for weeks 

 together looks wistfully, but vainly, for the welcome 

 breeze ; and where he realizes the scene so gra- 

 phically described in "The Eime of the Ancient 

 Mariner : " — 



"Day after day, day after day, 



We stuck, nor breath nor motion ; 

 As idle as a painted ship 

 Upon a painted ocean ;" — 



even here the smooth and glittering surface is not 

 at rest : for long, gentle imdulations, which cause 

 the taper mast-head to describe lines and angles 

 upon the sky, are sufficiently perceptible to tan- 

 talize the mariner with the thought that the breeze 

 which mocks his desires, is blowing freshly and gal- 

 lantly elsewhere. The most remarkable of the mo- 

 tions observable in the sea are the tides, periodical 

 risings and fallings in the height of the surface, 

 which take place twice every twenty-four hours, or 

 nearly. It is now well ascertained that these mo- 

 tions are caused by the attraction of the sun and 

 moon, but more particularly the latter, upon the 

 particles of water, which, moving freely among them- 

 selves with little force of cohesion, readily yield to 



♦ Isa. xl. 12. 



b3 



