2^6 Examination of St. Pierre's Ilyjnthefs 



tour, of it in 24 hours, like the rays of the fun. When 

 a hundlc of thefe effufions falls upon an ifland, it produces 

 there a tide of twelve hours, 1. e. of the fame duration with 

 that which the fun employs in heating the icy cupola through 

 which the meridian of that ifland paffes ; fuch are the tides 

 of the iflands of Otaheite, Mafiafuero, New Holland, New 

 Britain, &c. : each of thefe tides lafts as long as the courfe 

 of the fun above the horizon, and is regular like his 

 courfe. 



In the nothern part of the South fea the two continents 

 approach : they pour therefore by turns, in fummer, into the 

 chaiuvi which feparates them, the twafemi-diurnal effufions 

 of their pole, and there they collect by turns, in winter, thole 

 ot the fouth pole, which produces two tides a day as in the 

 Atlantic ocean. But as this channel about the 55 of N. lat. 

 ceafes to exift by the Hidden divergence of the continents of 

 Afia and America, thofe places only fituated in the point of 

 divergence of the northern parts of thefe two continents ex- 

 perience two tides a day. Such are the Sandwich Iflands. 

 Where fuch places are more expofed to the current of the one 

 continent than the other, its two femi-dturnal tides are un- 

 equal, 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 

 everyday, as at Kamtfchatka. Thus, two harbours may be 

 fituated in the fame fea under the fame parallel, and one 

 of them have two tides, ;.nd the duration of thefe tides, whe- 

 ther double or fingle, double equal or double unequal, regu- 

 lar or retarded, is always 13 hours every 24 hours, i. c. pre- 

 cifely the time the fun employs in heating that half of the 

 polar cupola from whence they flow ; which cannot poffibly 

 be referred to the unequal courfe of the fun between the tro- 

 pics, and much lefs to that of the moon, which is frequently 

 but a few hours above the horizon of fuch harbours. All 

 iflands are in the midft of currents : on looking therefore at 

 the fouth pole with a bird's-eye view, we fhould fee a fuc- 

 ceffion of archipelagos difperfed in a fpiral line all the way 

 to the northern hemifphere, which indicates the current of 

 the fea, juft as the projection of the two continents on the fide 

 of the north pole indicates the current of the Atlantic. Tims, 



the 



