Since the above was written, the statement is happily borne out by an official circular, issued by Lieutenant Maury, of the National Observatory, Washington, April 16th, 1851.  By that circular, it appears that precisely such a chart is in course of completion; and portions of it are presented in the circular.  “This chart divides the ocean into districts of five degrees of latitude by five degrees of longitude; perpendicularly through each of which districts are twelve columns for the twelve months; and horizontally through each of which districts are three lines; one to show the number of days that have been spent in each month in every district, and the two others to show the number of days in which whales, sperm or right, have been seen.”

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 which at these times he is said to swim, generally embraces some few miles in width (more or less, as the vein is presumed to expand or contract); but never exceeds the visual sweep from the whale-ship’s mast-heads, when circumspectly gliding along this magic zone.  The sum is, that at particular seasons within that breadth and along that path, migrating whales may with great confidence be looked for.

And hence not only at substantiated times, upon well known separate feeding-grounds, could Ahab hope to encounter his prey; but in crossing the widest expanses of water between those grounds he could, by his art, so place and time himself on his way, as even then not to be wholly without prospect of a meeting.

There was a circumstance which at first sight seemed to entangle his delirious but still methodical scheme.  But not so in the reality, perhaps.  Though the gregarious sperm whales have their regular seasons for particular grounds, yet in general you cannot conclude that the herds which haunted such and such a latitude or longitude this year, say, will turn out to be identically the same with those that were found there the preceding season; though there are peculiar and unquestionable instances where the contrary of this has proved true.  In general, the same remark, only within a less wide limit, applies to the solitaries and hermits among the matured, aged sperm whales.  So that though Moby Dick had in a former year been seen, for example, on what is called the Seychelle ground in the Indian ocean, or Volcano Bay on the Japanese Coast; yet it did not follow that