I had not been on deck more than a quarter of an hour when the blackness under the lower edge of the bank blink away over our starboard cathead began to pale, first to a cold slaty-grey, and from that, by rapid gradations, to a rich purple, then to crimson, and from crimson to an orange tint so deep as to be almost scarlet, beneath which the horizon loomed out black as ink, the intervening space of water lightening, as it swept toward us, until at the distance of a couple of miles it became a livid bluish-white.  This marked the western edge of the shoal, and sufficiently accounted for the smoothing of the deep-water in which we were sailing.