the honour of being regarded as the author of the true theory of the
phenomena presented by the wonderful planet.

Every person knows, in the present day, that Saturn consists of a globe
about 900 times greater than the earth, and a ring. This ring does not
touch the ball of the planet, being everywhere removed from it at a
distance of 20,000 (English) miles. Observation indicates the breadth of
the ring to be 54,000 miles. The thickness certainly does not exceed 250
miles. With the exception of a black streak which divides the ring
throughout its whole contour into two parts of unequal breadth and of
different brightness, this strange colossal bridge without piles had
never offered to the most experienced or skilful observers either spot
or protuberance adapted for deciding whether it was immovable or endued
with a movement of rotation.

Laplace considered it to be very improbable, if the ring was immovable,
that its constituent parts should be capable of resisting by their mere
cohesion the continual attraction of the planet. A movement of rotation
occurred to his mind as constituting the principle of stability, and he
hence deduced the necessary velocity. The velocity thus found was
exactly equal to that which Herschel subsequently deduced from a course
of extremely delicate observations.

The two parts of the ring being placed at different distances from the
planet, could not fail to experience from the action of the sun,
different movements of rotation. It would hence seem that the planes of
both rings ought to be generally inclined towards each other, whereas
they appear from observation always to coincide. It was necessary then
that some physical cause should exist which would be capable of
neutralizing the action of the sun. In a memoir published in February,
1789, Laplace found that this cause must reside in the ellipticity of
Saturn produced by a rapid movement of rotation of the planet, a
movement the existence of which Herschel announced in November, 1789.

The reader cannot fail to remark how, on certain occasions, the eyes of
the mind can supply the want of the most powerful telescopes, and lead
to astronomical discoveries of the highest importance.

Let us descend from the heavens upon the earth. The discoveries of
Laplace will appear not less important, not less worthy of his genius.

The phenomena of the tides, which an ancient philosopher designated in
despair as _the tomb of human curiosity_, wer