readily
observe in the phenomenal world. First of all comes astronomy,
including the phenomena exhibited in the heavens, beyond the limits of
the earth's atmosphere. Second, geology, which takes account of all
those actions which in process of time have been developed in our own
sphere. Third, physics, which is concerned with the laws of energy, or
those conditions which affect the motion of bodies, and the changes
which are impressed upon them by the different natural forces. Fourth,
chemistry, which seeks to interpret the principles which determine the
combination of atoms and the molecules which are built of them under
the influence of the chemical affinities. Fifth, biology, or the laws
of life, a study which pertains to the forms and structures of animals
and plants, and their wonderful successions in the history of the
world. Sixth, mathematics, or the science of space and number, that
deals with the principles which underlie the order of Nature as
expressed at once in the human understanding and in the material
universe. By its use men were made able to calculate, as in
arithmetic, the problems which concern their ordinary business, as
well as to compute the movements of the celestial bodies, and a host
of actions which take place on the earth that would be inexplicable
except by the aid of this science. Last of all among the primary
sciences we may name that of psychology, which takes account of mental
operations among man and his lower kindred, the animals.

In addition to the seven sciences above mentioned, which rest in a
great measure on the natural divisions of phenomena, there are many,
indeed, indefinitely numerous, subdivisions which have been made to
suit the convenience of students. Thus astronomy is often separated
into physical and mathematical divisions, which take account either of
the physical phenomena exhibited by the heavenly bodies or of their
motions. In geology there are half a dozen divisions relating to
particular branches of that subject. In the realm of organic life, in
chemistry, and in physics there are many parts of these sciences which
have received particular names.

It must not be supposed that these sciences have the independence of
each other which their separate names would imply. In fact, the
student of each, however, far he may succeed in separating his field
from that of the other naturalists, as we may fitly term all students
of Nature, is compelled from time to time to ca