New-York tribune., 1909-01-15
AFTER SHOCKS" IN ITALY.


What seems like an extraordinary series Of
EARTHQUAKES has followed the shock which ruined
AIessina on December 2S. Whether in frequency
and severity they have been abnormal can best
be determined by seismOgraphic records. Per
haps. however, the phenomena have not been 50
exceptional as might be supposed 1t is note
worthy that after all great disturbances of this
character trfing ones occur at irregular inter-
walls for weeks, and even months. Biologists
think that the relief which the first shock gives
TO the internal stresses that caused it may not
be complete and that further adjustments of the
rock strata may be necessary to restore equi-
librium In the present case the only serious
harm done wrought at the outset. Since
then no life has been lost, and such walls as
have been affected were tottering before It is n
matter for profound congratulatiOn that the
magnificent and venerable structures for which
Milan. Florence and Venice are famous were un-
injured.
Only the very natural and somewhat exag-
gerated alarm created can he placed to the dis
credit of these after shocks" Inasmuch as
they could have been foreseen and as there
at least probability that they would prove
comparatively harmless, it is unfortunate that
no effort was made by experts to speak reassur-
ingly to the Italians on the subject. This course
would have been more kind than the predicting
OF disasters which never came
II VIII be remeInpered UndI IN -Ine caDle uIS-
patches from Italy early f. the month Mr.. Frank
Perret an assistant of Professor Matteucc was
represented as asserting that serious trouble was
to he expected on January and s, when the
relative positions of the sun and moon will pro-
"duce the greatest strain" Now. as matter of
fact nothing happened on either Of those days
which was a whit more formidable than the
demonstrations preceding them for a week and
following for week The same may be said of
January G. the date of the last full moon, one Of
the two stages in the lunar month when the
ocean tides usually reach their maximum.
The moons influence depends not alone on its
combining with the sun in pulling. but also on
its nearness 70 the earth. It's orbit is SO shaped
that the distance at perigee is considerably less
than when it is in apogee- The highest tides
are observed when there is a combination of
either a new or full moon with the greatest
proximity There no such union of forces
on December 2S for though on that fatal day
the moon was comparatively near perigee, it
lust about TO enter on its first quarter. 1t
neither full nor new. Finally the shocks felt in
Northern Italy on January 13 occurred when the
moon was furthest from the earth and had bare
Iv begun its third quarter Yet they were fully
as severe as any for the fortnight Immediately
preceding.
Besides lack of correspondence between the
dates of earthquakes and the positions of the
moor and sun, repeatedly exposed by geoiogists,
there is another reason for discrediting the tidal
theory. which forecasts like Mr.. Perret's seem
TO b. based. The old theory that the interior of
the earth Is fluid mass has few exponents now
Though calculation indicates that at depth of
twenty or thirty miles the heat must be so in
tense that 1t would, If exerted at the surface
melt the hardest known subst ances a counter
acting influence is certainly at work Iabora-
tory experiments prove that pressure raises the
temperature at which any material will soften