That something more than a mere thunderstorm was impending there could now be no possible doubt.  The strange light of which I have spoken, and which had seemed to emanate from the clouds, had now vanished, giving place to a darkness so profound that it seemed to oppress us like some material substance; and the silence was as profound and oppressive as the darkness--so profound, indeed, was it that any accidental sound which happened to break in upon it, such as the occasional lap of the water against the boat's planking, the scuffling movement of a man, or the intermittent flap of the sail as the longboat stirred upon a wandering ridge of slow-moving swell, smote upon the ear with an exaggerated distinctness that was positively startling to an almost painful degree.  I accounted for this, at the time, by attributing it in part to the peculiar electrical condition of the atmosphere, and partly to the fact that we had all been wrought up to a condition of high nervous tension by the conviction that something--we did not quite know what--was impending, for which we were all anxiously on the watch, and that, in the Cimmerian darkness which enveloped us, we were obliged to depend for adequate warning, upon our hearing alone, which caused us to resent and be impatient of all extraneous sounds.  That this was to some extent the case was evidenced by the fact that, our preparations finished, we had, as with one consent, subsided into silence, which was broken only in a low whisper if anyone felt it necessary to speak.