New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1897-12-19

searches into tidal phenomena and for his skill
as a mathematician
Professor Darwin reminded his audience AT the
outset that the broad. low protubcrance which
Is lifted up the surface OF the ocean. ana
which gives rise to tides. IS the result OF the
moons and suns attraction The former body
Is responsible for the chief part OF the work
done Inasmuch as the hue waves thus Gre
ated sweep over the sea at the rate OF a thou-
sand miles an hour. there is a certain amount
Of friction between the water and the bed OF
the ocean And one OF the effects Of tidal frc-
ton IL to retard the rotation OF the earth on its
axis
Eut attraction IL always mutual analr' nj
least in physics This may not be true In ro-
nance. but it Is when the laws 81 gravitation
come into play. Therefore. while the moon IS
drawing up the water on the earth into n dome
like tidal wave the earth is pulling back on the
moon and trying to check ths onward night OF
IT'S satellite The latter influence. If continued
long enough. would. OF course. extend the p'riod
required for one complete revolution Of the moon
about the planet
There had not been any very percep'Ihle
lengthcning OF either the day or Tho month FRO
fessor Darwin said. In the last three THOUSAND
years Mon were justified In believing go ITO"
the fact that records Of eclipses rs long az" iS
that showed that the phenomena In question
occurred at just about the time that they "ouin
~ the combinations were based on days and
months Of the present length. However, IN"
causes which were n work must eventually
produce the predicted effect He would not say
how much time was required for that purpose.
He merely pointed to what seemed TO be a PROB
able. or at least possible. CONCLUSION. In MS
I,,,s t4sfatFf hon
was a much more conspicuous one than that Of
the month He was thus led to suppose that
eventually IT would take much time for the
earth to make one complete rotation AS IT would
for the moon to so once around the earth
when this coincidence between ia" day and
the month arrived. both would be. according to
Professor Darwin's calculation. just fifty five
Of the earth's present days in length. In other
words the day would be nfty- times rs long
AZ II Is now and what astronomers call the
"sidcrcal month would be exactly doubled in
length II will be readily perceived, on IA mo-
ments reflection, that If the moon should travel
around the earth at exactly the same rate aS
the earth rotated on its axis, the moon would
always be suspended above the same particular
meridian Of the carths longitude. one favored
SPOT on this terrestrial sphere would have an
exclusive monopoly OF the moonlight. The
Cambridge professors mathematics were made
ouatc to determine Just when this pause would
occur. Under these circumstances, obviously.
the earth would present the same side coatinu-
ously to the moon, as II the two bodies were
rigidly secured to the ends Of long rod. Such
q situation might seem a trille monotonOus TO
the inhabitants Of the moon But, as the moon
presents only side to the earth, ii would be
an even thing Besides, the moon probably has
NO Inhabitants. Its climate is altogether too