There is a vast _draught_ of _water_ poured continually out of the _Atlantick_ into the _Mediterranean_, the mouth or entrance of which between _Cape Spartel_ or _Sprat_, as the _sea-men_ call it, and _Cape Trafalgar_, may be near 7 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 _Streights_. By the benefit of this _Current_, tho' the wind be contrary, if it does not over-blow, _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 denomination to the _Streight_, and _Ceuta_ on the _Barbary_ coast: at which places _Hercules_ is supposed to have set up his _Pillars_. What becomes of this great quantity of water poured in this way, and of that, which runs from the _Euxine_ into the _Bosporous_ and _Propontis_, and is carried at last through the _Hellespont_ into the _Ægæan_ or _Archipelago_, is a curious _speculation_, and has exercised the wit and understanding 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 _Ægypt_, lying very low, and easily overflowable. They observe indeed, that the water rises 3 feet, or 3 feet and an half, in the _gulph_ of _Venice_, and as much, or very near as much, all along the _Riviera_ 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 _Christian_ shore: which latter I look upon as a meer fancy, and contrary to all observation. My conjecture is, that there is an _under-Current_, whereby 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 necessarily supposes an _under-Current_, I shall present you with an instance of the like nature in the _Baltick Sound_, as I received it from an able Seaman, who was at the making of the tryal.