ADVERTISEMENT. JXXI 



The tides have, in their very flux and reflux, 

 a perfedl conibnance with the general Currents of 

 the Ocean, and the courfe of the Sun. They flow 

 during twelve hours in one day, whether they be 

 divided into two tides of fix hours, by the projec- 

 tion of the two Continents, as in the northern He- 

 rn ifphere ; or whether they flow for twelve hours 

 uninterruptedly, as in the fouthern Hemifphere : 

 juft as the general Current of one Pole flows fix 

 months of the year. Accordingly, the tides, which 

 confift of twelve hours, in all cafes, are of a dura- 

 tion precifely equal to that which the Sun employs 

 in warming the half of the polar Hemifphere from 

 which they flow, that is one half-day ; as the ge- 

 neral Current which iffues from that Pole, flows 

 precifely during the fame time that the Sun warms 

 that whole Hemifphere, namely, during half the 

 year. But as the tides, which are only the polar 

 effufions of half a day, have refluxes equal to their 

 flux, that is, of twelve hours, in like manner, the 

 general Currents, which are the half-yearly eflu- 

 fions of a whole Pole, have refluxes equal to their 

 flux, that is of fix months, when the Sun puts thofe 

 of the oppofite Pole in a fl:ate of adivity. 



Did time and room permit, I could fliew how 

 thofe fame general Currents, which are the fecon- 

 dary moving principles of tiie tides, carry our Na- 



e 4 vigators 



