grand succession
of past events--a series of revolutions which the solid exterior of the
globe, and its living inhabitants, have experienced in times antecedent
to the creation of man.

In thus separating the two works, however, I have retained in the
"Principles" (book i.) the discussion of some matters which might fairly
be regarded as common to both treatises; as for example, an historical
sketch of the early progress of geology, followed by a series of
preliminary essays to explain the facts and arguments which lead me to
believe that the forces now operating upon and beneath the earth's
surface may be the same, both in kind and degree, as those which at
remote epochs have worked out geological changes. (See Analysis of
Contents of this work, p. ix.)

If I am asked whether the "Principles" or the "Manual" should be studied
first, I feel much the same difficulty in answering the question as if a
student should inquire whether he ought to take up first a treatise on
Chemistry, or one on Natural Philosophy, subjects sufficiently distinct,
yet inseparably connected. On the whole, while I have endeavored to make
each of the two treatises, in their present form, quite independent of
the other, I would recommend the reader to study first the modern
changes of the earth and its inhabitants as they are discussed in the
present volume, proceeding afterwards to the classification and
interpretation of the monuments of more remote ages.

CHARLES LYELL.

_11 Harley Street, London_, May 24, 1853.

_Dates of the successive Editions of the "Principles" and "Elements" (or
Manual) of Geology, by the Author._

Principles, 1st vol. in octvo, published in Jan. 1830.
----------, 2d vol. do. do. Jan. 1832.
----------, 1st vol. 2d edition in octavo 1832.
----------, 2d vol. 2d edition do. Jan. 1833.
----------, 3d vol. 1st edition do. May, 1833.
----------, New edition (called the 3d) of the whole work
in 4 vols. 12mo May, 1834.
----------, 4th edition, 4 vols. 12mo June, 1835.
----------, 5th do. do. do. Mar. 1837.
Elements, 1st edition in one vol July, 1838.
Principles, 6th do. 3 vols. 12mo June, 1840.
Elements, 2d edition in 2 vols. 12mo