The herald. [microfilm reel] (Los Angeles [Calif.]) 1893-1900, 1895-01-20

Tor US this evening to consider some OF
the extraordinary physical phenomena
connected 80 closely with the action OF
the tides, such as their surprising small
ness in midocean, in the Mediterranean
ses, the Caspian, the Baltic and other
confined areas their enormous heights,
on the other hand. in such places as the
English channel and the Bay Of Fundy.
The high tides of both of the latter
places are especially interesting to me,
having witnessed them personally from
the end of the three mile pier at Havre
on the channel, and from the wharfs at
st. John, N. B., on the Bay of Fundy.
Time, however, will not permit Of this,
and pass on at once to the considera-
ton OF the dynsmical question of the
friction which the tides are causing on
the earth and its effect of the diurnal
motion of the planet.
TIDE FRICTION.
No truth rests on moro firm foundaN
ton than the axiom that work cannot
be accomplished without the consump.
ton of energy in some OF its forms.
1t is based upon the immutable law
OF correlation OF forces. Now, the tides
are performing wonderful amount OF
work, rebuilding our continents, hol-
lowing out bays and aiding in the FORM
alton of bars, besides raising bodily al
the present time all the waters OF the
earth on an average three feet every "a
hours. In past ages the force displayed
was much greater, depending of course
upon the proximity OF the moon. Thus,
as we shall ace little later. when the
moon was only 40. 900, instead Of as OF
present 100000. miles from the earth,
the tides, instead OF averaging three
feet, did indeed average 6a8 feet in
height. Such a tide as that would
sweep almost any city from the face Of
the earth. Juat reflect upon what an
enormous. amount Of work ouch tides
must have been able to accomplish, and
what important factors they must have
been in the evolution of the esrly CON-
dition Of the earth's crust.
But from what source is che energy
derived at the expense OF which all this
work was sndiia today performed?
soRCE OF THE TIDE.CREATING POWER.
AS the moon ia che direct cause Of the
tides, it would, ut q superficial glance,
appear that We might be justified in at
tributing the source OF energy 20 our
satellite. But ie this true? Will it hold
good? No doubt it seems plausible, but
it is, nevertheless. q fallacy. To Illus
trate this, permit me to quote an Illus
tration from Sir Robert Bell. He says
that this is one OF those cases by no
means infrequent in dynamios, where
the truth ia widely different from what
oeems 10 be the case. and he illustrates
with example of rife which is fred by
tho pulling of trigger by the rifle
mans finger. No one would as
aert that the energy by which
the rife ball was fred off was supplied
by the riheman. Certainly not The
energy was of course due to the gun
powder, and all the rifleman did was to
provide the means by which the energy
stored up in the gunpowdsr became lib
Grated.
In almost the same way the tides
raised by the moon are aimp)Y the origl-
mating cause whersby certain amount
OF energy stored up in the earth itself is
liberated and applied to perform such
work az the tides are competent TO per-
form.
THE ANAL ROTATION -. ..
The store houas OF energy upon
VIII ich the tides through the agency Of
tho moon are making such large and
continuous drsfss is to be found ia the
momentum stored up in che sxial revo-
luton OF the planet. No doubt this is
an enormous store house of energy. No
doubt il seems to us all bus inexhausti~
BILE. But 40 the power drawn from it by
tho tides is not replaced, the irresisti-
BILE consequence 10 that the momentum
of rotation 10 being dissipated, and that
this rotation is slowly but surely de.
creasing and az @ result the day which
is now "a hours is becoming longer.
THE THEORY ORIGINATED WITH KANT.
II am not mistaken, it was Immnausl
Kant, who, more shan century ago
first called attention to the fact that the
tides in rolling from east to west were
reducing the earth's diurnal motion.
He showed that countless cons OF time
may elapee before this momentum
can be completely exhausted, but
| it ia nevertheless true that the energy
is decreasing and the relation of the
ear.h-moon system tending toward
equilibrium. At present the axial rev.
olution OF tho earth la not measurably
longer than it was 100 years ago. Even
in 1000 YEARS the change in the length
| of the day may perhaps be only frac-
ton of second. But tho Importance
attached TO this dissipation of momen-
tum lies Ia the fact that thia phenome =
non, though acting msjesticslly slow, 10
mot of rythmic nature but continues
right on oesslsssly and eternnlly in the
came direction.
LA PLACES THEORY AT FAULT.
La Places celebrated theory that OPP
posito currents are az to their effect
upon the rotation OF the earth as plus
and minus naught, and that there are
no forces ct work in nature which do
not always find their compromising OPP
posites, believe does not hold good in
the oase of tidal friction. Silently and
slowly though it be, the tides are never.
theleHs uninterruptedly acting az o
brake upon the rotation Of the earth,
and in millions OF years the accumu-
lated effect will not only become ap-
precisble but even of o startling magni-
tuds. Many attempts have been made
to compute this increase in the length of
the day, but OF course the results must
be taken with q good deal of reserve.
DIR. ]. b. Mayer, after an elaborate anal
ysis of the subject, arrives at a value Of
1.16 OF second for every $500 years.
SIR WILLIAM THoMsoN's CAL CULAmoNs.
Perhaps the best authority on the
subject is Sir William Thomson, who in
@ careful calculation of the age of the
esrth's crust shows that il cannot be