considerable numbers, and at length approached so that we could see
them on the ledges all over the sides of the mountain.

We had passed the skirt of the Craig, and were within half a mile,
or less, of its base. With the glass we could now see the entire
mountain-side peopled with the sea-fowl, and could hear their
whimpering, household cry, as they moved about, or nestled in
domestic snugness on the ten thousand ledges. The air, too, about
the precipices seemed to be alive with them. Still we had not the
slightest conception of their frightful multitude. We got about
against the center of the mountain when the swivel was fired, with
a reverberation like the discharge of a hundred cannon, and what a
sight followed! They rose up from that mountain--the countless
millions and millions of sea-birds--in a universal, overwhelming
cloud, that covered the whole heavens, and their cry was like the
cry of an alarmed nation. Up they went,--millions upon
millions,--ascending like the smoke of a furnace,--countless as the
sands on the sea-shore,--awful, dreadful for multitude, as if the
whole mountain were dissolving into life and light; and, with an
unearthly kind of lament, took up their lines of flight in every
direction off to sea! The sight startled the people on board the
steamer, who had often witnessed it before, and for some minutes
there ensued a general silence. For our own part, we were quite
amazed and overawed at the spectacle. We had seen nothing like it
before. We had never witnessed sublimity to be compared to that
rising of sea-birds from Ailsa Craig. They were of countless
varieties in kind and size, from the largest goose to the small
marsh-bird, and of every conceivable variety of dismal note. Off
they moved, in wild and alarmed rout, like a people going into
exile; filling the air, far and wide, with their reproachful lament
at the wanton cruelty which had driven them away.

This is only one of these breeding-places, but most of the rocky,
inaccessible cliffs and uninhabited islands of the northern and southern
shores of both continents are visited, at certain seasons, by sea-birds
in equally great numbers.

No subject connected with the history of birds furnishes more
interesting material for study than that of instinct. Young birds of
different species show that t