sufficient elevation. Mark observed that, from some cause or
other, the birds avoided the crater. It really seemed to him that their
instincts warned them of the dangers that had once environed the place,
and that, to use the language of sailors, "they gave it a wide berth,"
in consequence. Whatever may have been the cause, such was the fact; few
even flying over it, though they were to be seen in hundreds, in the air
all round it.

Chapter V.

"The king's son have I landed by himself;
Whom I left cooling of the air with sighs
In an odd angle of the isle, and sitting,
His arms in this sad knot."

_Tempest._

Having completed this first examination of the crater, Mark and Bob next
picked their way again to the summit of its wall, and took their seats
directly over the arch. Here they enjoyed as good a look-out as the
little island afforded, not only of its own surface, but of the
surrounding ocean. Mark now began to comprehend the character of the
singular geological formation, into the midst of which the Rancocus had
been led, as it might almost be by the hand of Providence itself. He was
at that moment seated on the topmost pinnacle of a submarine mountain of
volcanic origin--submarine as to all its elevations, heights and spaces,
with the exception of the crater where he had just taken his stand, and
the little bit of visible and venerable lava, by which it was
surrounded. It is true that this lava rose very near the surface of the
ocean, in fifty places that he could see at no great distance, forming
the numberless breakers that characterized the place; but, with the
exception of Mark's Reef, as Bob named the principal island on the spot,
two or three detached islets within a cable's-length of it, and a few
little more remote, the particular haunts of birds, no other land was
visible, far or near.

As Mark sat there, on that rock of concrete ashes, he speculated on the
probable extent of the shoals and reefs by which he was surrounded.
Judging by what he then saw, and recalling the particulars of the
examination made from the cross-trees of the ship, he supposed that the
dangers and difficulties of the navigation must extend, in an east and
west direction, at least twelve marine leagues; while, in a north and
south, the distance seemed to be a little, and a very little less. There
was necessarily a good deal of conjecture in this estimate of the extent
of the volcanic mountain wh