THE SALTS OF THE SEA. I99 



such a case, tliis warm sea water, when it comes to the cold lati- 

 tudes, would be brought to the surface through the instrumental- 

 ity of shell-fish, and various other tribes that dwell far down in 

 the depths of the ocean. Thus we perceive that these creatures, 

 though they are regarded as being so low in the scale of creation, 

 may nevertheless be regarded as agents of much importance in 

 the terrestrial economy ; for we now comprehend how they are 

 capable of spreading over certain parts of the ocean those benign 

 mantles of warmth which temper the winds, and modify, more or 

 less, all the marine climates of the earth. 



558. The makers of nice astronomical instruments, when they 

 have put the different parts of their machinery together, and set 

 it to work, find, as in the chronometer, for instance, that it is sub- 

 ject in its performance to many irregularities and imperfections ; 

 that in one state of things there is expansion, and in another state 

 contraction among cogs, springs, and wheels, with an increase or 

 diminution of rate. This defect the makers have sought to over- 

 come ; and, with a beautiful display of ingenuity, they have at- 

 tached to the works of the instrument a contrivance which has 

 had the effect of correcting these irregularities, by counteracting 

 the tendency of the instrument to change its performance with the 

 changing influences of temperature. 



559. This contrivance is called a compensation ; and a chro- 

 nometer that is well regulated and properly compensated will per- 

 form its office with certainty, and preserve its rate under all the 

 vicissitudes of heat and cold to which it may be exposed. 



560. In the clock-work of the ocean and the machinery of the 

 universe, order and regularity are maintained by a system of com- 

 pensations. A celestial body, as it revolves around its sun, flies 

 off under the influence of centrifugal force ; but immediately the 

 forces of compensation begin to act ; the planet is brought back 

 to its elliptical path, and held in the orbit for which its mass, its 

 motions, and its distance were adjusted. Its compensation is 

 perfect. 



561. So, too, with the salts and the shells of the sea in the ma- 

 chinery of the ocean ; from them are derived principles of com- 

 pensation the most perfect ; through their agency the undue effects 



