Delaware gazette and state journal. (Wilmington, Del.) 1883-1902, 1884-08-14
The Earthannke.

Sundays earthquake was felt over
large area, extending from Portland,
Maine, TO Washington, D. c., and from
Cape May to Cleveland, Ohio, but no
material damage has been reported from
any point. The New York Herald thus
summarizes some features Of the pertur-
baton:
Reports Of the direction OF the movement
vary, but so far as we can now gather from
the dispatches the general wave travelled
from a point about 10 degrees north of eaat
to the south of west. The seismic wave Of
October, 1870, has been traced with some
probability TO the feeble volcanic area lying
northeast of Quebec. But the facts in
the present case seem to point to the
great volcanic region encircling the
Azores as the ultimate source of
the disturbance. To that great centre Of
seismic commissions affecting the shores of
the Atlantic We must apparently trace so
marked and widespread q phenomenon. The
seismic shock was indeed simultaneous on
the seaboard with very decided atmospheric
pulsations, the barometer at this point regis
tering q remarkable wave Of pressure-from
80. 40 inches on Saturday midnight to 80. IL at
2 p. M, yesterday. This huctuation may
have contributed to the intensity OF the
earth tremor, but cannot alone have
originated 1t.
All theories as to the nature of earth
quakes diverge from common starting
point-that they are produced by the
same subterranean agency. The exist-
snoe of molten fluid mass in the centre
of the earth is the initial superstition Of
all theorists except Davy, who pro-
pounded chemical hypothesis,
which he afterwards abandoned,
but which is curious enough
to deserve mention. 1t was to the effect
that the metallic bases Of the earths and
alkalies, such as sodium, potassium,
magnesium and others, may abound in
an unoxidized state In the earth's in
terror that water may occasionally
| penetrate to these masses and,
combining with suon parts Thereof
as 1t came in contact with,
would set tree large volumes of gaseoui
matter, the metallic bases combining with
the oxygen Of the water and evolving
heat enough to melt the surrounding
rocks. The elastic gases thus liberated
and subjected to this intense heat would
he thought, produce explosions OF sufi
Client magnitude to account for earth
quakes.
An ingenious theory presented by Mr.
Mallet in an elaborate report to British
scientific association, asoribes earthquake
to volcanic causes. Mallet gees In vol
canoes the centres Of seismic disturbances
and notes that they are located near tn
sea or other supplies of water. An erur
tion may open up large assures in tn
volcanic region beneath the sea bottom
the rocky sides OF which are q
first so superheated that the waite
pouring into them assumes the spheroida
state instead of being converted int
steam; but, as these surfaces grow cooler
the imprisoned millions Of spheroids al
converted into vast volumes Of steal
which, explosively evolved, transmit
powerful impulse to the surrounding an
supernatant water, which is borr
onward with more or less foros to the lane
A recent theory assumes that grei
masses of semi-molten rock are adherir
to the interior surface of the earth
. ernst, and that through the action OF IL
, fiery pillows Of the seething sphere
! flame below one or more Of shese mass
! may be dislo 4ged and fall, psrhap
dozens Of miles; the sudden rupture vel
naturally setting up more or less seve
, motion in that portion of the crust und
! which 1t occurred.
The fact is that, although there ha'
been deplorable facilities afforded with
the past few years, in the terrible cart
quskes at Java Head and Csssamtcciol
for the study of selsmic phenomena, sole
tito men have found ont but little !
garding the cause and nature Of sart
: quskes but we may congratulate on
IA selves that our lot has been cast in
n region where, although we may be ]
a minded by an occasional tremor like th
' Of yesterday, that the surface of our glo
v is not 80 immobile as 1t looks, We are y
n not likely to be visited by any real
IL disastrous eafthuuake,