ocking mass and began to rush
rapidly outward in an ever-widening circle, its towering crest
surmounted by a roaring curling fringe of snow-white foam. Increasing
in height and in speed as it advanced, it rapidly attained an altitude
of fully sixty feet, bearing down upon the _Flying Fish_ so menacingly
that, for a few seconds, the party in the pilot-house stood paralysed
with consternation, expecting nothing less than that they would be
helplessly overwhelmed. The first to recover his presence of mind was
Mildmay, who, springing to the rods which controlled the air-valves,
pressed them powerfully down, throwing them all wide open and at once
ejecting from the hull both the water and the compressed air, and
causing the ship to rise until she floated lightly as an air-bubble on
the water. He then injected a dense body of vapour into the air and
water chambers, completing the vacuum; and the ship rose into the air
just in time to avoid the gigantic surge, which went hissing and roaring
close beneath them with a power and fury which fully revealed to them
the extent of the disturbance from which they had so narrowly escaped.
Other surges followed in quick rotation; but each was less formidable
than its predecessor, and in another ten minutes the surface had once
more subsided into a state of comparative calm.

As the _Flying Fish_ once more settled down upon the water and the air-
pump was set going, the professor turned to his companions and remarked:

"We have especial reason to congratulate ourselves and each other,
gentlemen, for we have to-day not only looked upon the magnificent
Humboldt Glacier under most highly favourable conditions, but we have
been also permitted to witness that even rarer sight, _the birth of an
iceberg_!"

They had indeed witnessed the birth of an iceberg, and that too of quite
unusual size; for, as soon as they dared, they approached the newly
fallen mass of ice closely enough to make a tolerably accurate
measurement of it; and they found that it was of nearly square shape,
measuring fully three-quarters of a mile along each of its four sides,
and towering to an average height of about three hundred and fifteen
feet above the surface of the water. The visible portion of the berg
constituted, however, only a small portion of its entire bulk, since
fresh-water ice floating in salt water shows above the surface only one-
eighth of its entire depth. This enormous berg, therefore, must have