ref pelting the Caufe of the Tides. 27S 



tfpcnally when fhe is at full ; for her rays poffefs an evapo- 

 rating heat, as the late experiments at Rome and Paris fully 

 demonftrate * ; much lefsfhall I involve myfelf in a difcuffiori 

 of the tides of the fouth pole, which in fummer in the open 

 fea come in vaft fiirges from the fouth and fouth-weft. There 

 are two tides every day ; becaufe the fun warms by turns, 

 every 24 hours, the eaft and weft fide of the pole in fufion. 

 Precifely the fame effect takes place in lakes fituated in the 

 vicinity of icy mountains, which have a flux and reflux in 

 the day-time only. But it cannot be doubted that, if the fun 

 warmed, during the night, the other fide of thefe mountains, 

 they would produce another flux and reflux ; and confe- 

 quently two tides in 24 hours, like the ocean. 



We are not to imagine that every tide is a polar effufion 

 of the particular day on which it happens, but an effect of 

 the feries of polaT effufions ; fo that the tide which takes 

 place on our coafts to-day, is perhaps part of that which took 

 place fix weeks ago. But here, too, muft we admire the 

 harmony of nature : the evening and morning tides take 

 place on our coafts as if they iffued that very day from the 

 higher and lower part of our hemifphere ; and the tides of 

 fummer are precifely oppofite to the tides of winter, as are 

 the tides from whence they flow ; our evening tides in fum- 

 mer, and our morning tides in winter, being greateft. 



If the tides are ftronger after the full moon, it is becaufe 

 that luminary increafes by her heat the polar effufions, and 

 confequently the quantity of water in the ocean. 



Let us now explain why the tides of the South fea do not 

 refemble thofe of the Atlantic ocean. The irregular effufion* 

 of the poles, not being narrowed in the fouthern hemifphere, 

 as in ours, produce on the fhores of the Indian ocean and 

 South fea expanfions vague and intermitting. The fouth 

 pole has not, like the north pole, a double continent, which 

 feparates into two the divergent effufions daily produced by 

 the fun : it has no channel in paffing through which its 

 effluxes fhould be retarded : its effufions accordingly flow di- 

 rectly into the vaft fouthern ocean, forming on the half of 

 that pole a feries of divergent emanations which perform the 



* I do not know where any account of tlicfe ftrange experiments can be 



f0WKl.—W. 



N n * tour 



