 been captured or seen.
    While thus employed, the heavy pewter lamp suspended in chains over his
head, continually rocked with the motion of the ship, and forever threw shifting
gleams and shadows of lines upon his wrinkled brow, till it almost seemed that
while he himself was marking out lines and courses on the wrinkled charts, some
invisible pencil was also tracing lines and courses upon the deeply marked chart
of his forehead.
    But it was not this night in particular that, in the solitude of his cabin,
Ahab thus pondered over his charts. Almost every night they were brought out;
almost every night some pencil marks were effaced, and others were substituted.
For with the charts of all four oceans before him, Ahab was threading a maze of
currents and eddies, with a view to the more certain accomplishment of that
monomaniac thought of his soul.
    Now, to anyone not fully acquainted with the ways of the leviathans, it
might seem an absurdly hopeless task thus to seek out one solitary creature in
the unhooped oceans of this planet. But not so did it seem to Ahab, who knew the
sets of all tides and currents; and thereby calculating the driftings of the
sperm whale's food; and, also, calling to mind the regular, ascertained seasons
for hunting him in particular latitudes; could arrive at reasonable surmises,
almost approaching to certainties, concerning the timeliest day to be upon this
or that ground in search of his prey.
    So assured, indeed, is the fact concerning the periodicalness of the sperm
whale's resorting to given waters, that many hunters believe that, could he be
closely observed and studied throughout the world; were the logs for one voyage
of the entire whale-fleet carefully collated, then the migrations of the sperm
whale would be found to correspond in invariability to those of the
herring-shoals or the flights of swallows. On this hint, attempts have been made
to construct elaborate migratory charts of the sperm whale.6
    Besides, when making a passage from one feeding-ground to another, the sperm
whales, guided by some infallible instinct - say, rather, secret intelligence
from the Deity - mostly swim in veins, as they are called; continuing their way
along a given ocean-line with such undeviating exactitude, that no ship ever
sailed her course, by any chart, with one tithe of such marvellous precision.
Though, in these cases, the direction taken by any one whale be straight as a
surveyor's parallel, and though the line of advance be strictly confined to its
own unavoidable, straight wake, yet the arbitrary vein in
