A History of Science, vol 3 | Page 5

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 earth's surface have been forming throughout untold

ages, and that successive populations differing utterly from one another
have peopled the earth in different geological epochs. The entire point
of view of thoughtful men becomes changed in contemplating the
history of the world in which we live--albeit the newest thought harks
back to some extent to those days when the inspired thinkers of early
Greece dreamed out the wonderful theories with which our earlier
chapters have made our readers familiar.
In the region of natural philosophy progress is no less pronounced and
no less striking. It suffices here, however, by way of anticipation,
simply to name the greatest generalization of the century in physical
science--the doctrine of the conservation of energy.

I
THE SUCCESSORS OF NEWTON IN ASTRONOMY
HEVELIUS AND HALLEY
STRANGELY enough, the decade immediately following Newton was
one of comparative barrenness in scientific progress, the early years of
the eighteenth century not being as productive of great astronomers as
the later years of the seventeenth, or, for that matter, as the later years
of the eighteenth century itself. Several of the prominent astronomers
of the later seventeenth century lived on into the opening years of the
following century, however, and the younger generation soon
developed a coterie of astronomers, among whom Euler, Lagrange,
Laplace, and Herschel, as we shall see, were to accomplish great things
in this field before the century closed.
One of the great seventeenth-century astronomers, who died just before
the close of the century, was Johannes Hevelius (1611-1687), of
Dantzig, who advanced astronomy by his accurate description of the
face and the spots of the moon. But he is remembered also for having
retarded progress by his influence in refusing to use telescopic sights in
his observations, preferring until his death the plain sights long before
discarded by most other astronomers. The advantages of these
telescope sights have been discussed under the article treating of Robert
Hooke, but no such advantages were ever recognized by Hevelius. So
great was Hevelius's reputation as an astronomer that his refusal to
recognize the advantage of the telescope sights caused many
astronomers to hesitate before accepting them as superior to the plain;

and even the famous Halley, of whom we shall speak further in a
moment, was sufficiently in doubt over the matter to pay the aged
astronomer a visit to test his skill in using the old-style sights. Side by
side, Hevelius and Halley made their observations, Hevelius with his
old instrument and Halley with the new. The results showed slightly in
the younger man's favor, but not enough to make it an entirely
convincing demonstration. The explanation of this, however, did not lie
in the lack of superiority of the telescopic instrument, but rather in the
marvellous skill of the aged Hevelius, whose dexterity almost
compensated for the defect of his instrument. What he might have
accomplished could he have been induced to adopt the telescope can
only be surmised.
Halley himself was by no means a tyro in matters astronomical at that
time. As the only son of a wealthy soap-boiler living near London, he
had been given a liberal education, and even before leaving college
made such novel scientific observations as that of the change in the
variation of the compass. At nineteen years of age he discovered a new
method of determining the elements of the planetary orbits which was a
distinct improvement over the old. The year following he sailed for the
Island of