OF TIDES. 343 



The moon also dissolves ice by the humidity of the atmosphere. 

 When the moon shines in winter nights in all her lustre it freezes 

 very sharply, because the north wind checks the evaporating influ- 

 ence of the moon : but if the wind is stilled ever so little, you see 

 the heavens covered with vapours which exhale from the earth, and 

 you find the atmosphere softened. 



Nature having determined to indemnify the poles for the sun*s ab- 

 sence, makes the moon pass toward the pole, which ihe sun abandons: 

 she crystallises, and reduces into brilliant snows, the waters which 

 cover it : she renders its atmosphere more refractive, that the sun's 

 presence may be detained longer in it, and restored sooner to it : 

 and hence also there is reason to conclude she has drawn out the 

 poles of the earth in order to bestow on them a longer participation 

 of the sun's influence. We may judge from analogy the general 

 effect of the tides : a source discharging itself into a bason pro. 

 duces at the sides of that bason a backward motion or counter cur- 

 rent, which carries straws and other floating substances up towards 

 the source. 



Charlevoix (Hist, of New France) tells ns that, though the wind 

 was contrary, he sailed at the rate of eight leagues a day up the lake 

 Michigan, against its general currently the assistance of its lateral 

 counter.curreuts 



M. de Crevcoeur assures us, that in sailing up the Ohio, along its 

 banks he made 422 miles in fourteen days, or ten leagues a day, by 

 means of the counter-currents, which have always a velocity pro- 

 portional to that of the principal current. 



The particular effects observed in lakes and rivers communicating 

 with icy mountains, illustrate the nature of the polar effusions. A 

 kind of flux and reflux in the lake of Geneva, during summer and 

 towards the evening, is observable, occasioned by the melting of the 

 snows, which fall into it after noon in greater quantities than at other 

 seasons of the day. The intermittence of certain fountains is 

 ascribable to the same cause. The frequent and rapid fluxes (ten 

 or twelve times a day) of the Euripus, the strait separating Boeotia 

 from Eubcea, arise from the same source. 



The currants of the ocean are reducible to two general ones : one, 

 during our summer, from the north pole, in a south direction; the 

 other, during our winter, proceeding northward from the south 

 pole. 



