OF TIDES. 347 



rower, and carries before it at once the whole mass of the waters of 

 the Atlantic ocean, without permitting a single column to escape 

 either to the right or left. However, if it meet a cape or strait to 

 oppose its course, it would form there a lateral current, as at 

 Cape St. Augustin, and in Africa about 10 N. Jat.; for in the sum- 

 mer of the south pole the currents and tides return south on the 

 American, and east on the African side, the whole length of the 

 gulph of Guinea, in contradiction to all the laws of the lunar 

 system. 



From these polar effusions the principal phenomena of the tides 

 may be explained. It will be evident, for example, why those of 

 the evening should be stronger in summer than those of the morn. 

 ing; because the sun acts more powerfully by day than by night on 

 the ices of the pole on the same meridian as ourselves: and also 

 why our morning tides in winter rise higher than those of the even- 

 ing, and why the order of our tides changes every six months; be- 

 causej the sun being alternately towards both poles, the effect of the 

 ilides must be opposite, like the causes which produce them. At 

 ihe solstices the tides are lower than at any other season of the year, 

 and those likewise are the seasons when there is most ice on the 

 two poles, and consequently least water in the sea: the reason 

 is obvious, the winter solstice is with us the season of the greatest 

 cold ; of course there is the greatest possible accumulation of ice oa 

 our pole and hemisphere. At the south pole it is indeed the sum- 

 mer solstice ; but little ice is then melted, because the actien of the 

 greatest heat is not felt there as with us, till the earth has an acquired 

 heat superadded to the sun's action, which takes place six weeks 

 following the summer solstice. 



At the equinoxes, on the contrary, we have the highest tides; and 

 these are precisely the seasons when there is least ice at the two 

 poles, and of course the greatest quantity of water in the ocean. 

 At our autumnal equinox in September, the greatest part of the 

 ices of the north pole is melted, and those of the south pole begin to 

 dissolve. The tides in March rise higher than those in September, 

 because it is the end of summer to the south poles which contaiws 

 much more ice than ours, and consequently sends a greater mass of 

 water to the ocean. 



I shall say nothing (he proceeds) of the intermittence of the polar 



