but the main sweep of development has to do in each
case with the nineteenth century. We shall see at
once that this is a time both of rapid progress and of
great differentiation. We have heard almost nothing
hitherto of such sciences as paleontology, geology, and
meteorology, each of which now demands full attention.
Meantime, astronomy and what the workers of the
elder day called natural philosophy become wonderfully
diversified and present numerous phases that
would have been startling enough to the star-gazers
and philosophers of the earlier epoch.

Thus, for example, in the field of astronomy, Herschel
is able, thanks to his perfected telescope, to discover
a new planet and then to reach out into the
depths of space and gain such knowledge of stars and
nebulae as hitherto no one had more than dreamed of.
Then, in rapid sequence, a whole coterie of hitherto
unsuspected minor planets is discovered, stellar distances
are measured, some members of the starry
galaxy are timed in their flight, the direction of movement
of the solar system itself is investigated, the
spectroscope reveals the chemical composition even of
suns that are unthinkably distant, and a tangible
theory is grasped of the universal cycle which includes
the birth and death of worlds.

Similarly the new studies of the earth's surface reveal
secrets of planetary formation hitherto quite inscrutable.
It becomes known that the strata of the