250 PHYSICAL GEOGRAPHY OF THE SEA, AOT) ITS METEOROLOGY. 



though they are regarded as beings 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 wliich temper the winds, and modify, more or less, all 

 the marine chmates of the earth. 



489. The makers of nice astronomical instruments, when they 

 The regulators of havo put the different parts of their machinery to- 

 ^^^''^^- gether, and set it to work, find, as in the chrono- 



meter, for instance, that it is subject 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 overcome ; and with a beautiful dis- 

 play of ingenuity, they have attached to the works of the instru- 

 ment 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 tempera- 

 ture. This contrivance is called a comjjensatioii ; and a chrono- 

 meter or clock that is well regulated and properly compensated 

 will perform its office -with certainty, and preserve its rate under 

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

 In the clock-work of the ocean and the machinery of the uni- 

 verse, 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 distances were adjusted. Its compensation is per- 

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

 chinery of the ocean; fi'om them are derived principles of com- 

 pensation the most perfect ; tlirough their agency the undue 

 effects of heat and cold, of storm and rain, in disturbing the equih- 

 brium and producing thereby currrents in the sea, are compensated, 

 regulated, and controlled. The dews, the rains, and the rivers are 

 continually dissolving certain minerals of the earth, and carrying 

 them off to the sea. This is an accumulative process ; and if it 

 were not comijensated, the sea would finally become, as the Dead 

 Sea is, satm-ated with salt, and therefore unsuitable for the habita- 

 tion of many fish of the sea. The sea-shells and marine insects 

 affi)rd the required com^pensation. They are the conservators of 



