OF TIDES. 849 



effusions of the pofes, not being narrowed in the southern hemisphere, 

 as in ours, produce on the shores of the Indian ocean and South sea 

 expansions vague and intermitting. The south pole has not, like the 

 north pole, a double continent, which separates into two the divergent 

 effusions daily produced by the sun : it has no channel in passing 

 through which its effluxes should be retarded : its effusions accordingly 

 flow directly into the vast southern ocean, forming on the half of that 

 pole a series of divergent emanations which perform the tour of it 

 in 24 hours, like the rays of the sun. When a bundle of these effu- 

 sions falls upon an island, it produces there a tide of twelve hours, 

 ". <?. of the same duration wilh that which the sun employs in heating 

 the icy cupola through which the meridian of that island passes ; 

 sach are the tides of the inlands of Otaheite, Massafuero, New 

 Holland, New Britain, &c. : each of these tides lasts as long as 

 the course of the suu above the horizon, and is regular like his 

 course. 



In the northern part of the South sea the two continents ap- 

 proach : they pour therefore by turns, in summer, into the channel 

 which separates them, tjie two semi-diurnal effusions of their pole, 

 and there they collect by turns, in winter, those of the south pole, 

 which produces two tides a day as in the Atlantic ocean. But as 

 this channel about the 55 of N. lat. ceases to exist by the sudden 

 divergence of the continents of Asia and America, those places 

 only situated in the point of divergence of the northern parts of 

 these two continents experience two tides a day. Such are the 

 Sandwich Islands, Where such places are more exposed to the 

 current of the one continent than the other, its two semi-diurnal 

 tides are unequal, as at the entrance of Nootka Sound : but when 

 it is completely out of the influence of the one, and entirely under 

 that of the other, it receives only one tide of twelve hours every 

 day, as at Kamschatka. Thus, two harbours may be situated in 

 the same sea under the same parallel, and one of them have two 

 tides, and the duration of these tides, whether double or single, 

 double equal or double unequal, regular or retarded, is always 12 

 hours every 24 hours, i. e. precisely the time the sun employs in 

 heating that half of the polar cupola from whence they flow; which 

 cannot possibly be referred to the unequal course of the sun be- 

 tween the tropics, and much less to that of the moon, which is 



