Daily globe. [volume] (St. Paul, Minn.) 1878-1884, 1882-11-01
THE EAKTH's TREMORs.
Some Remarkable Facts aud Deduction
Relative to the Force of Lamar Attfac-
Stons and tidal Inf xences.

Some Remarkable Facts aud Deduction
Relative to the Force of Lamar Attrac-
stons and Tidal Irfxences.
Baltimore Sun.
A report read recently before the British
association by committee composed of
George Fl. Darwin, Horace Darwin, Sir
William Thomson and others on the results
of an inquiry they had been directed to
make into the force of lunar attraction
presents some facts and deductions re-
speeding the yielding nature of the earth's
crust that are as remarkable as they are
unexpected. The committee devised, as a
means to the end in view, an instrument of
extreme delicacy to measure the DETECTION
from the perpendicular experienced by a
plumb line under the moons pull, reason
ing that, the weight of the bob on the line
and the moons distance at different points
of its orbit being known, the attraction ex-
erted by the lunar mass would furnish a
basis for important differences.
When it came to trial, however. it was
found that there were other forces besides
that of the moon in operation, forces vari-
able in amount and direction, whose exis-
tence to the extent manifested had pre-
viously been unexpected. The experiment.
ors in the first place needed, of course. a
quiet, still spot on which to set their in
strument. But it could not be found.
The earth was too shaky. 1t was never
still. The first tests were made at Cam
bridge. Then it was thought that at the
bottom of deep mine. several thousand
feet beneath the earth's quivering surface,
terra 6rma might be expected to exist, and
the instrument was moved to such a posi-
ton. But the fixed point was not found.
The instrument responded to the moon. but
it also responded in greater or lesser de-
gree to the tides laundering against the
coast miles away. 1t even indicated
with great distinctness the approach and re-
cession of masses Of air, wing with the
meteorol ogist's favorite instrument in de-
tecting those states of atmospheric density
and tenuity corresponding to the terms
''high barometer" and "low barometer -
Had these phenomena been the only ones.
or had they been presented singly ,unmixed
with others, they might have been allowed
for and the lunar Investigations might
have been proceeded with. But they were
inextricably confused.
These facts are sufficiently curious. but
| the deductions derieved from them are
more so. The committee estimate, for ex-
ample, that an increase in the weight of
! the atmosphere answering to a rise of one
| inch in the barometer depresses the solid
| earth beneath it as much as two or three
inches and the sea as much as foot. The
| tides twice day sink the coast line beneath
| them, as they come in, fully five inches,
| the earth of course rising or rebounding
that much again when relieved of the i'm
| mense weight of water that constitutes a
| tidal wave. Sir William Thomson and the
Darwins estimate that at the distance of
| sixty miles inland from the English coast
| the tidal wave exerts direct attractive
force quite equal to that of the moon while
| the readings of the instrument are dis
turbed also by the thorough shaking of the
earths crust which the tide occasions. The
young Darwins proceeded to calculate from
the above data the amount of subsistence
| the earth's surface suffers. from the weight
| of mountains, and attain some surprising
results.
Sir William Thomson holds indeed, that
the crust of the earth may be compared
with a layer Of jelly on plate, and the eff
feet of the superintendent mass of water
or solid rock be ikened to the depression
produced by coin laid ~ on the surface
of the jelly. Tremors follow and are re.
newed with every disturbance Of surround
ing conditions. Such thing as absolute
repose is impossible. AS long as winds
chase each other over the face of the earth.
attended by or following alterations OF
| high and low barometer, and as long as the
tides continue to beat upon our coasts
neither the philosopher intent on the high
problems of human destiny, the eremite
| tired of busy life, nor the scientist in want
| of fixed location for his Instruments will
be able to find the perfect quiet he seeks