lanet which a mighty explosion broke up into several portions
each moving at different velocities.

"According to our hypothesis, the comets are strangers to our planetary
system. In considering them, as we have done, as minute nebulosities,
wandering from solar system to solar system, and formed by the
condensation of the nebulous matter everywhere existent in profusion in
the universe, we see that when they come into that part of the heavens
where the sun is all-powerful, he forces them to describe orbits either
elliptical or hyperbolic, their paths being equally possible in all
directions, and at all inclinations of the ecliptic, conformably to what
has been observed. Thus the condensation of nebulous matter, by which
we have at first explained the motions of the rotation and revolution
of the planets and their satellites in the same direction, and in nearly
approximate planes, explains also why the movements of the comets escape
this general law."(3)

The nebular hypothesis thus given detailed completion by Laplace is a
worthy complement of the grand cosmologic scheme of Herschel. Whether
true or false, the two conceptions stand as the final contributions
of the eighteenth century to the history of man's ceaseless efforts to
solve the mysteries of cosmic origin and cosmic structure. The world
listened eagerly and without prejudice to the new doctrines; and that
attitude tells of a marvellous intellectual growth of our race. Mark the
transition. In the year 1600, Bruno was burned at the stake for teaching
that our earth is not the centre of the universe. In 1700, Newton was
pronounced "impious and heretical" by a large school of philosophers
for declaring that the force which holds the planets in their orbits
is universal gravitation. In 1800, Laplace and Herschel are honored for
teaching that gravitation built up the system which it still controls;
that our universe is but a minor nebula, our sun but a minor star, our
earth a mere atom of matter, our race only one of myriad races peopling
an infinity of worlds. Doctrines which but the span of two human lives
before would have brought their enunciators to the stake were now
pronounced not impious, but sublime.

ASTEROIDS AND SATELLITES

The first day of the nineteenth century was fittingly signalized by the
discovery of a new world. On the evening of January 1, 1801, an Italian
astronomer, Piazzi, observed an apparent star of about the eighth
magnitude (hence