We contrived to complete all our preparations before it became too dark to see; and it was well for us that we did so, for when the darkness came it was a darkness that might be felt, for it was as though we were hemmed in by great black walls which might be touched by merely stretching forth one's hand, while the heat of the stagnant atmosphere was so oppressive as to cause the perspiration to pour from us in streams.  This disagreeable state of affairs continued without break of any kind until about five bells in the first watch, when a cry of astonishment and alarm broke from the watch on the forecastle-head at the sudden appearance on the bowsprit of a ball of light of a sickly greenish hue, which I immediately recognised as a corposant, although I had never seen one before, but had frequently heard them spoken of and described.  It was certainly a weird and uncanny sight to behold under such circumstances, and was well-calculated to strike awe into the minds of superstitious seamen, both from the suddenness and the mystery of its appearance, and from its ghostly and unnatural aspect as it poised itself out there on the end of the spar, clinging tenaciously thereto, and alternately flattening and elongating as it swayed in unison with the violent movements of the schooner.  And while the men were still gaping at it, open-mouthed, its sickly radiance faintly illuminating their faces and causing them to wear the horrible aspect of decomposing corpses, two others appeared, one on each of the lower mast-heads.  For perhaps two minutes, or it might have been a little longer, these last two ghostly lanterns swayed and lengthened and contracted with the wild plungings of the little craft.  Then the one on the foremast-head let go its hold and went drifting away astern until it was lost to sight, while the one on the mainmast-head came gliding down the spar until it reached the flooded deck, and vanished as though extinguished by the washing of the water.  While this was happening, the corposant on the bowsprit-end also let go its hold and came floating inboard along the spar, causing a regular stampede of the watch, who incontinently came rushing aft as far as the mainmast, to get out of the way of their uncanny visitor, which, however, vanished as it reached the knightheads.