354 CURRENTS, GULPH-STREAMS r 



Christian shore, which latter I consider as a mere fancy, and con- 

 trary to all observation. 



" My conjecture is, that there is an under-current, by which as 

 great a quantity of water is carried out as comes flowing in. To 

 confirm which, besides what I have said above about the difference 

 of tides in the offing, and at the shore in the Downs, which neces- 

 sarily supposes an under-current, 1 shall present you with an instance 

 of the like nature in the Baltic sound, as I received it from an able 

 seaman, who was at the making of the trial. He told me, that 

 being there in one of the king's frigates, they went witlf their pin. 

 nace into the mid stream, and were carried violently by the current; 

 that soon after they sunk a bucket with a large cannon ball, to a 

 certain depth of water, which gave check to the boat's motion, and 

 sinking it sjill lower and lower, the boat was driven ahead to wind, 

 ward against the upper current : the current aloft, as he added, not 

 being four or five fathom deep, and that the lower the bucket was 

 let fall, they found the under current the stronger/* 



Of upper currents, Mr. Rennell has particularly described a very 

 singular one often prevailing to the westward of Scilly, and dan 

 gerous to ships that approach the British Channel *. They are, 

 however, more frequently met with about the Straits of Gibraltar, 

 and near the Antilles. These latter are especially worthy of notice, 

 and are thus described and accounted for by Dr. Peysennel |. 



The coasts of these American islands are subject to counter- 

 tides, or extraordinary currents, which render it very dangerous to 

 chaloupes and other small craft to land ; while at the same time 

 the boats and ships in the roads are scarcely ever sensible of them, 

 and seldom incommoded by them ; nor do those who are out at 

 sea appear to be affected by them. It is however certain that a 

 regular wind constantly blows, in these parts of the torrid zone, 

 from the tropic of Cancer, to the equinoctial line, from the east ; 

 inclining sometimes northward,' and sometimes southward. This 

 wind is called alize, or trade-wind, for reasons admitted by philo- 

 sophers, and it draws the water westward, giving a total and uni. 

 form course to that immense quantity, which conies from the great 

 river of the Amazons, and from an infinite number of other rivers, 

 which discharge themselves into the ocean. These currents passing 



* Phil. Trans. 1793. Vol. Ixxxiii. f Jb, 1755* Vol.xlix. 



