The Caycos Bank is a shoal lying some sixty-eight miles off Monte Christi, on the north coast of Hayti.  It measures about the same distance from its north-western to its south-eastern extremity, and is about sixty-two miles across from east to west at its widest point; it is consequently of considerable extent, and from the fact that the depth of water over it ranges from six feet to eighteen feet it is not without its dangers, and must be approached with due caution, especially during the hours of darkness.  In daylight the danger is not nearly so great, because the north-eastern and north-western edges of the shoal are fringed by a number of cays among which the sea breaks heavily, while the whole surface of the shoal is white water.  And it is this same white water which gives rise to the phenomenon above referred to, locally known as "Bank Blink."  It is simply the reflection of the phosphorescence of the water in the clouds above; and the darker and more overcast the night, the more distinctly is the reflection seen. The phenomenon is, of course, quite natural and easily to be accounted for, yet its occurrence can scarcely be regarded as less than providential; for there can be no doubt whatever that its appearance in the sky has often been the means of warning navigators that they were approaching this danger, and so causing them to haul off in time to avoid shipwreck.