time when the biological cell was
unrecognised, and the theory of evolution had not yet been formulated.
The rapidity with which advances of knowledge were made in the physical
sphere was astonishing, and it was only to be expected that they should
have seemed not a little bewildering. We must try to note the main
steps of the movement, giving the names of some of the representative
workers and thinkers.

It is generally agreed that the foundations of modern chemistry were
laid by Dalton (1808). He it was who revived the old atomic theory,
and determined the weights of the atoms and the {22} proportions in
which they are combined into molecules--the smallest particles which
could exist in a free condition. By so doing he prepared the way for
the subsequent researches of Faraday and Clerk-Maxwell into the
properties of electricity and magnetism, and for the investigations by
Helmholtz and others into the connexion between electric attraction and
chemical affinities.

The forerunner of the wonderful advances of modern biology was the
French naturalist Lamarck (1809), who, in opposition to the accepted
doctrine of separate creations, suggested that all the species of
living creatures, not excepting the human, have arisen from older
species in the course of long periods of time. The common parent forms
he held to have been simple and lowly organisms, and he accounted for
the gradual differentiation of types by the hypothesis that they were
the results of the inheritance of characteristics which had been
acquired by continued use--as, for example, in the case of the giraffe
who was supposed to have owed the length of its neck to the efforts of
its ancestors to browse upon trees that were just beyond their reach.
He maintained that the changes produced in the parents by temperature,
nutrition, repeated use or disuse, were inherited so that they
reappeared in their offspring. But the evidence adduced was {23}
judged to be insufficient, and the balance of scientific opinion was
decidedly against his views.

Lyell (1830) gave a new direction to the science of geology by
accumulating evidence to prove the certainty of a natural and
continuous development in the formation of the crust of the earth, thus
opposing the catastrophic idea which had previously prevailed. One
outcome of his researches was to make it plain that the history of this
development must have extended over enormous tracts of time.

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