Training of a Geologist. — Van Hisc. 151 
with reference one to another, and indeed are constantly re- 
made. Furthermore, the molecules and even the atoms which 
compose the atmosphere, hydrosphere and lithosphere have 
motions of marvelous intricacy and speed. These motions 
of the atmosphere, th; hydros])here, and the lithosphere are 
all superimposed upon the astronomical motions — the wob- 
bling revolution of the earth about its axis, the revolution of the 
earth-moon couple about their common center of gravity, the 
movement of this couple about the sun at the rate of 68,000 
miles per hour, the movement of the solar system among other 
systems. If it were possible for one to fix in space coordinates 
by which to measure these various motions, the movement of an 
air particle, of a water drop, of a mineral grain, would be seen 
to be extraordinarily complex. 
It is clear that there is every reason to believe that no atom 
or molecule in the world ever occupies the same absolute posi- 
tion in space at any two successive moments. Indeed, it must 
have been an extraordinary accident, if a single particle has oc- 
cupied in all tile history of the universe exactly the same posi- 
tion that it has occupied at any ]3revious time. No such thing 
as rest for any particle of matter anywhere in the earth or 
in the universe is known. On the .contrary, everywhere all 
particles are -moving in various ways with amazing speed. 
No science is independent of other sciences, but geology 
is peculiar in that it is based upon so many other sciences. 
Astronomy is built upon mathematics and physics. Chemis- 
try and physics to a considerable degree are built upon each 
other. Physics also requires mathematics. Biology demands 
a limited knowledge of physics and chemistry. However, it 
cannot be said that a knowledge of the basal principles of 
more than one, or at most t\AO, other sciences is an absolute 
prerequisite for a successful pursuit of astronomy, chemistry, 
physics or biology. This is not true of geology. In order to 
go far in general geology one must have a fair knowledge of 
physics, chemistry, mineralogy and biology. These may be 
called the basal sciences of geology. In certain lines of geol- 
ogy the additional sciences, mathematics, astronomy and met- 
allurgy, are very desirable. 
