Evening star., 1886-09-01

HOW IT WAS OBSERVED By PROF. NJ GEE
EARTHQUAKES OCCURRING CONSTANTLY
THIS ONE MORE SEVERE THAN UsUAL-ITs
FORCE, DURATION AND DIRECTION.
Major Powell, the director of the United States
geological survey, was interviewed to-day and
made the following statement: "The earth
quake was well observed by Mr. ]. w. McC}ee,
OF the geological survey, in the third land
upperl story of a brick house, 1424 Corcoran
street. After the elimination Of the first shock
the phenomena were timed. A rough substi-
tute for seismoscope was improvised out OF a
tumbler OF water placed on a stand in the
center Of the room, and the high head-board
OF the bedstead served as a rude seismometer.
The following is the record:
Time.-Time OF elimination of the first shock
Uoth meridian), 9:54l2 pm.
Duration OF first snock (estimated) thirty
seconds.
Time of termination OF the same. s:55.
Time of termination Of slight iremors TO-
timed)
Time Of recommencement of continuous tre-
mors. zoos.
Time of elimination of the second shock.
Duration of second shock about thirty
seconds,
Time of termination of second series Of tre-
mors, 1913
lmpro'ised seismoscope the horizontal direc-
ton was from n. 500 T. to f., T. e. "A very little
north of east; but there was an indeterminate
Nertlcai component in the unduation very per-
ceptlbie in the motions of liquids and OF arti-
Giles oi furniture. Roughly, the upward impulse
In each vibration appeared TO be q third or a
nalf OF the lateral impulse.
The Rate of NiDration.-This was measured
on the high swinging headboard OF a bedstead
curing the second shock and found TO be lis or
12O per minute.
Amplitude of vibrat,on.-During the second
shock the headboard. Sla feet high, swung
through an arc of from L, 10 q. of an inch III
was estimated that the amplitude of oscillation
during the earlier shock Was twice or thrice rs
great.
EARTHQUAKES IN THE UNITED STATES AND
C'NADA.
During 1885 there were recorded the follow
ing earthquakes in the United States and
Canada: Canadian provinces 8; New England
5; Atlantic states, 8; Mississippi valley, 8; Pa
cifc slope, "a; total, SO.
During the twelve years, 1S72-'S3, there
have been recorded in the United states and
canada 364 earthquakes. distributed AS fol-
From this list it appears that in the entire
area earthquakes occur on AN average once In
l2 days, and once month i'm the Atlantic
slope. Many OF these disturbances are, how
ever, SO slight as to be unperceiyed by the ma-
jority OF the people; and IL should be observed
that tne list Is more complete IN the densely
populated and frequently shaken Atlantic
slope than IN either The seldom shaken Missis-
slppi valley or the sparsely populated Pacific
slope.
usually accepted by geologists is something
like this: The earth is believed TO be inclosed
by solid crust OF rock, OF variable thickness in
different regions. This crust rests upon mate
rial in u more or less nuid condition, SO that A.
readily Yields to agencies Of reformation, like
water or molten iron.
The reasons believing that the interior is
In somewhat nuid condition are various. The
lFrom very many observations made In mines
artesisn wells, etc, 1t Is discovered that there
is an increase of temperature from the sur.a ace
downward, anu that this Increase Ia great
that a degree of heat sufficient TO melt All
known rocks Is soon reached.
z. BY certain geologic agencies certain rocks
from below Drought to the surface in noun
tain building. and THESE rocks SHOW evidence of
wing been greatly heated, ana even OF hav-
B. Molten matter in very large quantities
comes up from the interior OF the eartn through
crevices and volcanic vents.
Besiues these lines OF evidence there are many
accessory iacLs which tell the same story The
interior OF tue earth Is constantly losing neat In
u variety OF ways. A small amount is probably
conducted 10 the surface aud radiaIed into
space A large amount Of neat Is conveyed
from the interior through the agency OF not
springs. Sucn springs are found In many Dor
tfOns OF the known earth, and in u few districts
are very abundant, and through them much
heat is conveyed from The interior u the sur
lace, wulcn Is there radlated into space The
lavas that are drought up yieid vast stores OF
heat, all OF which is lost TO the earth through
radiation. Tue secular cooling which results
from Lie above Causes must necessarily dimiu.
lsI the magnitude OF The earth, and as IL snrlnKs
the solid exterior crust must in some manner
yield SD rs To conform 70 The lesser magnitude
thus produced.
rue stresses produced in the crust of the
earth 10y the shrinking Of the interior are modi-
he'd 10y another class agencies. Tue Land sur
lace OF the earth is washed by rains and rivers.
and IN the a. gregate large bodies oi material
are carried away aud deposited in lake boltom,
which are gradually nled up and espes ialiy
deposited aiOng ine shores Oh the seas The uu-
loaainy Of Land areas anu the overloading ot
Certain water areas 10 a Large extent loc.,iizes
Ii. Again, The mud or plastic material of the
interior cnanses its position beneath the
crust OF the eartII, and porllous oI
II How out as iavas; ,hus an additional set OF
stresses Is established. Thus, stresses are esLab
lsned tnr"us IA the agency Of a coutrs.ctins ln-
terror through loading and unioadIng at the
10 iaVa-beds where such matter is poured cut
upon the surface The stresses produced uy the
Various agencies thus described gradually be-
come So great that at last the crust vi the earth
must yield and earthquakes are produced.
GEOLOGIC FACTS.
The occurrence of earthquakes in the eastern
portion of Ihe United States seems TO be related
in a very interesting way 10 certain geologic
iacts observed in the region. At least u cousid-
cradle share of the Atiautic slope earLnauanes
are supposed TO have n sequential connection
with a line OF dispiacemeut passing through
the Caroiinas, Virginia, Mary yiand, Delaware
tor some time past been q subject OF iuvestiya.
tion by the geological survey. In Georgia aud
LOe SdrOil1dS lC Is represented by n general
seaward tilung OF the surface, Guques-
tionabiy Connected with suOterranean
anu in Virginia this wide.
spread uiting begins to concentrate in a
definite line OF displacement which ina
the latitude OF fredericksburg Is gentle ilou-
ociinal; G., the rock strata are there locally
bent DOWNWARD, aud here as well AS elsewhere
aIOag tue displacement, the land toward The
sea Is depressed and that toward the mountains
is elevated. La the latitude OF Washington the
displacement becomes either u close nexure or
fracture, aud lies in the Eastern Branch. Its
amount here Is so fcet. At the head OF CnesA-
peake bay the displacement Is lou ieeL and it
appears 10 increase nortnward, reaching 2Uo or
3UO ieet N The lower Hudson valley. Tue whole
VI this movement has probably occurred in
pOst-Q ua teruary times, and Is still in progress
Indeed, 1t may be Questioned whether any
general geographic movement any part OF
the earth's suriace during any period OF
geologic time has been much more energetic
and raptd than that now taxing place along the
AtianLc slope; aud our comparative imm unity
frOm serious cal tnQuak here Is ~ be aLtuUu ed
not 50 much To absence OF these gr at eartn
movements resulting In The formation OF noun
tain Chains and even the upneavAl OF conti-
nents, rs to the probably less pruiouud depth
noun nLainous regions, and especially 70 the
tact tnat no volcanic vents have been estab-
lished."
Changes In the Omces.
h w. Winsheil, clerk Of class ]. adjutant
generals Office, has resigned.
Charles +. McDermott has been permanently
appointed q copybolder In the war records