10 Fourteen miles Bright green Much less thick from Cadiz 11 Between Capes Deep Indigo Very little matter, St. Mary and Vincent very pure 12 Off the Burlings. Strong green Thick, with fine matter 13 Beyond the Burlings Indigo Very little matter, pure 14 Off Cape Finisterre Undecided Less pure 15 Bay of Biscay Black-indigo Very little matter, very pure 16 Bay of Biscay Indigo Very fine matter. Iridescent 17 Off Ushant Dark green A good deal of matter 18 Off St. Catherine's Yellow-green Exceedingly thick 19 Spithead Green Exceedingly thick Here we have three specimens of water, described as green, a clearer green, and bright green, taken in Gibraltar Harbour, at a point two miles from the harbour, and off Cabreta Point. The home examination showed the first to be thick with suspended matter, the second less thick, and the third still less thick. Thus the green brightened as the suspended matter diminished in amount. Previous to the fourth observation our excellent navigating lieutenant, Mr. Brown, steered along the coast, thus avoiding the adverse current which sets in, through the Strait, from the Atlantic to the Mediterranean. He was at length forced to cross the boundary of the Atlantic current, which was defined with extraordinary sharpness. On the one side of it the water was a vivid green, on the other a deep blue. Standing at the bow of the ship, a bottle could be filled with blue water, while at the same moment a bottle cast from the stern could be filled with green water. Two bottles were secured, one on each side of this remarkable boundary. In the distance the Atlantic had the hue called ultra-marine; but looked fairly down upon, it was of almost inky blackness--black qualified by a trace of indigo.