AND TEMPERATURE OF THE SEA. 



shore, in that part of the Downs three hours, which is, grossly 

 speaking, the time of half a tide, before it is so off at sea. The 

 reason of this diversity of tides I take to be from the meeting of 

 the two seas in that narrow strait. Often when the wind has blown 

 hard at N. E. or at W. or W. and by S. there has happened an alter- 

 ation of the tides in the Thames, which ignorant people have tnis. 

 takingly reckoned a prodigy. And, it is a most certain observation, 

 that where it flows tide and half tide, though the tide of flood runs 

 aloft, yet the tide of ebb runs under foot, that is, close by the 

 grour.d ; and so at the tide of ebb, it will flow under foot. 



" Now, as to the Straits, there is a vast draught of water poured 

 continually out of the Atlantic into the Mediterranean ; the mouth 

 or entrance of which between Cape Spartel or Sprat, as the seamen 

 call it, and Cape Trafalgar, may be near seven leagues wide, the 

 current setting strong into it, and not losing its force till it runs as 

 far as Malaga, which is about 20 leagues within the Straits. By the 

 benefit of this current, though the wind be contrary, if it does not 

 overblow, ships easily turn into the Gut, as they term the narrow 

 passage, which is about 20 miles in length. At the end of which 

 are two towns, Gibraltar on the coast of Spain, which gives deno- 

 mination to the strait, aud Ceuta on the Barbary coast ; at which 

 places Hercules is supposed to have set up his pillars. What be- 

 comes of this great quantity of water poured in this way, and of 

 that which runs from the Euxine into the Bosphorus and Propontis, 

 and carried at last through the Hellespont into the ^Egean or Archi- 

 pelago, is a curious speculation, and has exercised the ingenuity of 

 philosophers and navigators. For there is no sensible rising of the 

 water all along the Barbary coast, even down to Alexandria, the 

 land beyond Tripoli, and that of Egypt lying very low, and easily 

 to be overflowed. They observe, indeed, that the water rises three 

 feet or three feet aud in the gulf of Venice, and as much, or very 

 near as much, all along the river of Genoa, as far as the river Arno; 

 but this rather adds to the wonder. 



" I here omit to speak at large of the several hypotheses which 

 have been invented to solve this difficulty ; such as subterraneous 

 vents, cavities, and indraughts, exhalations by the sun-beams, the 

 running out of the water on the African side, as if there were a kind 

 of circular motion of the water, and that it only flowed in upon the 



VOL. lu, 2 A 



