STUDY IV. 203 



their mountains, and to the rivers which flow from 

 them, we fliall be able to form fome faint idea of 

 thofe proportions which the glaciers of the Poles 

 bear to the whole Globe and to the Ocean. The 

 Cordeliers of Peru, which are onl}'^ mole -hills, com- 

 pared to the two Hemifpheres, and the rivers, which 

 ifTue from them, only rills of water compared to 

 the Sea, have felvages of ice, from twenty to thirty- 

 leagues broad, briftled, at their centre, with pyra- 

 mids of fnow from twelve to fifteen hundred fa- 

 thoms high. What, then, muft be the elevation 

 of thefe two domes of polar ice, which have, in 

 Winter, bafes of two thoufand leagues in diame- 

 ter ? I can have no doubt, that their thicknefs, at 

 the Poles, muft have reprefented the Earth as oval, 

 in central eclipfes of the Moon, conformably to 

 the obfervations of Kepler and Tycho Brhaë, 



I deduce another confequence from this confi- 

 guration. If the elevation of the polar ices is ca- 

 pable of changing in the Heavens the apparent 

 form of the Globe, their weight muft be fuffi- 

 ciently confiderable to produce fome influence on 

 it's motion in the Ecliptic. There is, in faft, a 

 very fingular correfpondence between the move- 

 ment, by which the Earth alternately prefents it's 

 two Poles to the Sun, in one year, and the alter- 

 nate effufions of the polar ices, which take place 

 in the courfe of the fame year. Let me explain 



my 



