The Indiana State sentinel. [volume] (Indianapolis) 1868-1895, 1885-01-21
OF WHAT Is OUR EARTH, ITS AGE
ETC2

The terrible earthquakes which have re-
Gently almost depopulated some of the
towns of Spain and terrified the people of
certain sections of our own country sug-
gested, perhaps, the recent paper of the emil
nen5 astronomer, Mr.. Proctor: ut may in
terest many to learn in this connection"
says he,.."that in the California regions of
disturbance, the most active on the North
American continent, astronomical and geo
deticsl observations indicate not only q
most irregular arrangement OF the matter
forming the esrtb's crust, but slss that
changes are taking place beneath the
surface" The direction of gravity,
he says, Is altered by the attractions
Of irTegularly distributed masses under the
crust, and in such degree that distances
measured do not correspond with distances
indicated by astronomical observations
Moreover, ''the reflections observed now are
not the same Is those observed thirty years
ago. It Is clear then that irregularities exist
beneath the crust such "a may at any time
lead to susterrsnesn commissions in North
America"
The old theories were that earthquakes
were the result OF internal fires. which, gen.
Grating steam through ocean leakage, would
produce explosions. Proctor says, in regard
to this matter: while We still recognize in
ternsl heat as the immediate cause of sab
terranean movements, We recognize as the
cause of this heat the energy pervsding the
esrth's mass. 1t ia the esrth's attractive en-
ergy, steadily acting npon her crust, which
generates the heat by Which that crust is dis
turbed." The philosophy of this principle
may be thus briefly expoundec for the general
reader. By the loss Of the earth's internal
heat and the gradual contraction of It's
masses OF solid substance, room Ia left"
according to this philosopher, 'for the move
ment inward of the rock substances of the
crust, with crushing, grinding action, &C.
companied sby the generation OF immense
heat" Thus. he adds, 30 long "a the force
of gravity continues to have matter to sot
upon efficiently, the earth's vitality will
continue. According to this theory-which
Mr. Proctor says Is an established fsot''-
the tendency is toward diminished nantes
tation of earthquake energy; but the: ten
dency isse slowly developed as to practically
amount TO nothing In any one century.
''The eerth's vitality is apparently the same
now as 1t was thousand years ego,
and as 1t will be a thousand years
hence" 1t seems slight process, this
Glow, steady and insensibe contraction OF
the esrth's crust, and people can not see
how 1t can generate force lin the form of
heat) that produces earthquakes. 'tBut,"
says the astronomer, "whatever amount of
heat Is required to expand given mass in
such and such degree, the same precise
amount Of heat will be generated by the con-
traction of the mass in that degree. When
we consider what tremendous heat wo1ld
be required to expand the globe Of the earth
30 that its surface should be messurably in
creased, we see how processes of contraction,
altogether too slight to produce measurable
dimunition of any part of the esrth's sur
face, correspond to most effective local sc-
cessions of temperature"