From the 5th of December, the pilots believed they took successively the measurement at a distance of the island of Ranas (Morant Keys), Cape Portland and Pedro Keys. They may probably have been deceived in several of these distances, which were taken from the mast-head. I have elsewhere noted these measurements, not with the view of opposing them to those which have been made by able English navigators in these frequented latitudes, but merely to connect, in the same system of observations, the points I determined in the forests of the Orinoco and in the archipelago of the West Indies. The milky colour of the waters warned us that we were on the eastern part of the bank; the centigrade thermometer which at a distance from the bank and on the surface of the sea had for several days kept at 27 and 27.3 degrees (the air being at 21.2 degrees) sank suddenly to 25.7 degrees. The weather was bad from the 4th to the 6th of December: it rained fast; thunder rolled at a distance, and the gusts of wind from the north-north-east became more and more violent. We were during some part of the night in a critical position; we heard before us the noise of the breakers over which we had to pass, and we could ascertain their direction by the phosphoric gleam reflected from the foam of the sea. The scene resembled the Raudal of Garzita and other rapids which we had seen in the bed of the Orinoco. We succeeded in changing our course and in less than a quarter of an hour were out of danger. While we traversed the bank of the Vibora from south-south-east to north-north-west I repeatedly tried to ascertain the temperature of the water on the surface of the sea. The cooling was less sensible on the middle of the bank than on its edge, a circumstance which we attributed to the currents that there mingle waters from different latitudes. On the south of Pedro Keys the surface of the sea, at twenty-five fathoms deep, was 26.4 and at fifteen fathoms deep 26.2 degrees. The temperature of the sea on the east of the bank had been 26.8 degrees. Some American pilots affirm that among the Bahama Islands they often know, when seated in the cabin, that they are passing over sand-banks; they allege that the lights are surrounded with small coloured halos and that the air exhaled from the lungs is visibly condensed. The latter circumstance appears very doubtful; below 30 degrees of latitude the cooling produced by the waters of the bank is not sufficiently considerable to cause this phenomenon. During the time we passed on the bank of the Vibora the constitution of the air was quite different from what it had been when we quitted it. The rain was circumscribed by the limits of the bank of which we could distinguish the form from afar by the mass of vapour with which it was covered.