INTRODUCTION. 21 



very beautiful and instructive instance it is of that 

 unerring skill and wisdom with which the whole 

 constitution is ordered and kept in order, by Him, 

 who, with minute accuracy, " weigheth the mountains 

 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 undulations, 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. 



