ow living in Europe, and which are either extinct or live in
more southern climates, and others in tropical seas. Also that the bones
and teeth of elephants and of the rhinoceros and hippopotamus found in
Siberia and elsewhere in northern Europe and Asia indicate that these
animals must have lived there, though at present restricted to the
tropics. In his last essay, _Epoques de la Nature_ (1778), he claims
that the earth's history may be divided into epochs, from the earliest
to the present time. The first epoch was that of fluidity, of
incandescence, when the earth and the planets assumed their form; the
second, of cooling; the third, when the waters covered the earth, and
volcanoes began to be active; the fourth, that of the retreat of the
seas, and the fifth the age when the elephants, the hippopotamus, and
other southern animals lived in the regions of the north; the sixth,
when the two continents, America and the old world, became separate; the
seventh and last being the age of man. Above all, by his attractive
style and bold suggestions he popularized the subjects and created an
interest in these matters and a spirit of inquiry which spread
throughout France and the rest of Europe.

But notwithstanding the crude and uncritical nature of the writings of
the second half of the eighteenth century, resulting from the lack of
that more careful and detailed observation which characterizes our day,
there was during this period a widespread interest in physical and
natural science, and it led up to that more exact study of nature which
signalizes the nineteenth century. "More new truths concerning the
external world," says Buckle, "were discovered in France during the
latter half of the eighteenth century than during all preceding periods
put together."[66] As Perkins[67] says: "Interest in scientific study,
as in political investigation, seemed to rise suddenly from almost
complete inactivity to extraordinary development. In both departments
English thinkers had led the way, but if the impulse to such
investigations came from without, the work done in France in every
branch of scientific research during the eighteenth century was excelled
by no other nation, and England alone could assert any claim to results
of equal importance. The researches of Coulomb in electricity, of Buffon
in geology, of Lavoisier in chemistry, of Daubenton in comparative
anatomy, carried still farther by their illustrious successors towards
the