where it passed through it!--a mere eyelet-hole--a pin-hole--closed
up at once by the constant movements which take place in the tail of
the comet. And yet in that moment of contact the side of the earth
facing the comet might be covered with hundreds of feet of _débris_.

Or, on the other hand, the comet may, as described in some of the
legends, have struck the earth, head on, amid-ships, and the shock
may have changed the angle of inclination of the earth's axis, and
thus have modified

[1. Schellen, "Spectrum Analysis," p. 392.]

{p. 95}

permanently the climate of our globe; and to this cause we might look
also for the great cracks and breaks in the earth's surface, which
constitute the fiords of the sea-coast and the trap-extrusions of the
continents; and here, too,

###

THE GREAT COMET OF 1811.

might be the cause of those mighty excavations, hundreds of feet
deep, in which are now the Great Lakes of America, and from which, as
we have seen, great cracks radiate out in all directions, like the
fractures in a pane of glass where a stone has struck it.

The cavities in which rest the Great Lakes have been attributed to
the ice-sheet, but it is difficult to comprehend how an ice-sheet