The times dispatch. [volume] (Richmond, Va.) 1903-1914, 1910-04-22
shc Nature OF EnrtI,aunke..

! To settle dispute Will you give me
! some information regarding the nature
! of earthquakes? " Y. r.
| The following facts on the general
subject contain the gist of the most
recent scientific Investigations: From
what has been said regarding the
formation and structure of the earth's
crust. II appears we are living on the
surface of spherical she'll. composed
OF rock and soil OF variable and I'M
or ten miles or twenty, fifty or even
one hundred miles. and that this shell
has been broken into innumerabie
fragments, which, are floating on a
sea OF semi-plastic and molten rock,
and this again resting on core or
globe OF intensely heated gas Most
people think that at the depth of loo
or 1000 miles the pressure on the
matter beneath must be tremendous.
but such is not the case, as we now
body on She earth's surface depends
on Its mass and the force OF gravity
The former Is constant, the latter is
variable. depending on it's distance
from the centre OF the earth. and on
Its latitude or angular distance from
the equator. Above the earth the force
OF gravity varies inversely as the
square of the distance OF the centre
the attraction OF a sphere on external
bodies being the same as II the entire
INlSg were tL the very
centre--but below the surface gravity
varies directly as the distance from
the centre. The full significance Of
this statement Will be better under
stood by saying that If a pound of
matter att the eartl's surface could
he taken half way 10 the centre tnoar-
~ 1000 miles below tine surface). IT
would weigh only half pound. II
taken only three -fourths Of the way
1t would weigh only ono-fourth of
pound, and &c taken TO the centre ii
would have no weight at all because
ii would then be equally attracted in
all directions. The pressure beneath
the surface is then not so great as
most persons imagine. a body below
the surface is attracted only BY the
sphere whose radius is equal 70 the
body's distance from tho centre. and
then only directly as the distance, that
Is TO say the nearer the centre, the
less the attraction. The attraction of
the various parts of tie smell neutFaltZe
each other For instance. II a body
be placed anywhere within a hollow
shell, assuming, OF course, that IL is
OF Uniform thickness and density it
viii remain at rest. Again, all mat
ter can be reduced TO the gaseous con-
dition BY sufficient heat, and converse
~ all gases can be reduced 10 the
liquid or solid state BY pressure UNI
der certain restrictions of tenlpera-
ture. which we. now proceed TO e%-
plain. At ordinary temperature
pressure of about four atmospheres
(sixty pounds 20 the square inch) Will
Gondcnse chlorine gas TO a liquid. but
at higher temperature, say III de-
grees Fair, that OF steam. no pres
sure whatever would liquefy II. There
IS temperature common to all bodies
in a gaseous condition, but different
for each gas, above which they cam
not be condensed to a LIQUID by any
pressure that can be applied This par
ticular temperature at which they
liquefy Is called the critical temper
asit.c of that gas. Hydrogen. oxygen,
carbon dioxide. methane and other
gases have been subjected 10 pres