rffpeSllng the Canfe of the Tulfs. 269 



bodies of ices, alternately accumulated and diffolved, at the 

 two poles, muft occafion a very perceptible augmentation ot 

 its waters at their return to it by the action of the fun, and 

 a great diminution by their reduction to ice when the luu 

 retires. It has been calculated that the earth and fea covered 

 with ice, may be equalled to T-ioth of the whole ocean, and 

 the height of the polar ices is at lead 600 feet ; a mafs which 

 in melting muft add i-ioth, that is 60 feet, to the level of 

 the ocean. 



Nature has diftributed fandy zones to affift, at the proper 

 feafon, in accelerating the fufion of the polar ices. The winds 

 in fummer convey the igneous particles with which thefe 

 zones are tilled towards the poles, where they affift the fun's 

 action on the ices. 



The moon alfo diflblves ice by the humidity of the atmo- 

 fphere. When the moon mines in winter nights in all her 

 Inure it freezes very fharply, becaufe the north wind checks 

 the evaporating influence of the moon : but if the wind is 

 Hilled ever fo little, you fee the heavens covered with vapours 

 which exhale from the earth, and you feel the atmoh 

 foftened. 



Nature having determined to indemnify the poles for the 

 fun's abfence, makes the moon pafs toward the pole, which 

 the fun abandons : (lie cryilallifes, and reduces into brilliant 

 fnows, the waters which cover it; (lie renders its atmoiphere 

 more refractive, that the fun's prefence may be detained longer 

 in it, and reftored fooncr to it : and hence alfo there is reafon to 

 conclude (lie has drawn out the poles of the earth in order to 

 beftow on them a longer participation of the fun's influence. 

 We mav judge from analogy the general effect of the tides : 

 A fource difeharging itfelf into, a bafon produces at the fides of 

 that bafon a backward motion or counter current, which car- 

 ries draws and other floating fubftanccs up towards the fource. 



Charlevoix (Hid. of New France) tells us that, though the 

 wind was contrary, he failed at the rate of eight leagues 

 a day up lake Michigan, againft its general current, by the 

 aflittance of it» lateral counter-currents. 



M. de Crevcceur allures us, that in failing up the Ohio, 

 along its banks he made 42 1 miles in 14 days, or ten leagues 



a-dav, 



