3i2 OF TIDES. 



2j; a thing impossible, and the circumstance can be ascribed to 

 no other cause than his real elevation. 



St. Pierre cuts the difficulty arising from the different vibrations 

 of the pendulum, by observing that they are liable to a thousand 

 errors. 



The elongation of the poles being thus demonstrated, the current 

 of the seas and tides follows as a natural and necessary conse* 

 quence. 



Let us now consider the extent of the polar ices, and the powers 

 capable of effecting their solution. 



The polar ices in the winter proper to each hemisphere are from 

 six to seven thousand leagues in circumference ; but in their sum. 

 mer, from two to three thousand. 



The ices and snows form in our hemisphere, in January, a cupola, 

 the arch of which extends more than two thousand leagues over t lie 

 two continents, with a thickness of some lines in Spain, some inches 

 in France, several feet in Germany, many fathoms in Russia, and 

 beyond the 60 of north latitude of some hundred feet. Some 

 ice islands were seen by Ellis from fifteen to eighteen hundred feet 

 above the level of the sea, and they probably go on increasing to 

 the pole to a height indeterminable. Hence the enormous aggre- 

 gation of water, fixed by the cold of winter in our hemisphere, 

 above the level of the ocean, is clearly perceptible ; and to the 

 periodical fusion of these vast masses the general movement of the 

 seas and tides is justly ascribable. The ices at the south pole 

 exceed in quantity those at the north ; and two such bodies of 

 ices, alternately accumulated and dissolved, at the two poles, must 

 occasion a very perceptible augmentation of its waters at their 

 return to it by the action of the sun, and a great diminution by 

 their reduction to ice when the sun retires. It has been calculated 

 that the earth and sea covered with ice, may be equalled to 1-lOth 

 of the whole ocean, and the height of the polar ices is at least 600 

 feet; a mass which in melting must add l-10tb, thaFis 60 feet, to 

 the level of the ocean. 



"Nature has distributed sandy zones to assist, at the proper sea- 

 son, in accelerating the fusion of the polar ices. The winds in 

 summer convey the igneous particles with which these zones are 

 filled towards the poles, where they assist the sun's action on 

 ices* 



