46 



stronger the current was found. The upper current ap- 

 peared by this experiment, not above four or five fa- 

 thom deep. 



And does not the following instance shew that there is 

 an under current at the mouth of the Mediterranean 

 sea 1 la the year 1?12, Mous. i'Aigle, commander of a 

 privateer, chasing a Dutch ship near Ceuta Point, came 

 up with her in the straits between Tariffa and Tangier, 

 and giving her one broad side sunk her. A few days af- 

 ter this ship with her cargo of brandy and oil arose near 

 Tangier, four leagues west of that place, where she sunk, 

 and directly against the strength of the current. Cer- 

 tainly then the deep water in the middle of the straits, 

 sets outward to the grand ocean. And possibly j^reat 

 part of the water, which runs in at the straits, may run 

 out again that way. 



One of the most violent currents in the northern seas, 

 runs between two of the western isles. The sea begins 

 to boil with the tide of flood, and increases gradually 

 till there are many whirlpools, which form themselves 

 into a sort of pyramids, and immediately spout as high 

 as the mast of a little vessel. At the same time they 

 make a loud report These white waves run two 

 leagues before they break. The sea continues these mo- 

 tions, till it is more than half flood, and then decreases 

 gradually, till it has ebbed half an hour. From that 

 time it boils again, till it is within an hour of low-water. 

 This boiling of the sea is about a pistol-shot distant 

 from the isle of Scarba. But the smallest boat may 

 safely cross the gulpb, at the last hour of the flood or 

 or of the ebb. 



In like manner, the collision of the opposite and ob- 

 lique streams, near the end of the Orkney inlands, ex- 

 cites a circular motion in the water, and when the swift- 

 ness of the tide is considerable, occasions whirlpools or 

 cavities in the sea, in the form of an inverted bell, wide 

 at the mouth, and growing gradually narrower towards 

 the bottom. Their width and depth are in proportion to 

 the rapidity of the streams that cause them. Thx>se in 

 Peutland Firth, near the islands Storma and Swona, 



