Omaha daily bee., 1914-09-29
Mystery Of the Tide and Moon

still be 6S.75o times as high as those
raised by the moon.
There must be some other law in opera
ton. and in searching for 1t you may re-
call the principle of inverse squares" to
which have often referred in these ar
ticles. According to that principle the
attractive force of a body like the sun
varies inversely as the square of distance.
Let US try this, and see II 1t will help us
, out.
The square of 400 is 10000. Since this
! is to be taken inversely we divide the
/ 25,5 900. representing the tidal power of
the sun relatively to that of the moon
when the two bodies are at the same dis
tance, by 10000, and the quotient is
nearly 160. which shows US that we have
not yet found the true law, for the solar
tides, instead of being 100 times higher
than the lunar ones, are less than half
as high.
Nbw IT, instead of simply squarng the
400 which represents the distance of the
sun as compared with the moons dis
tanoe, we cube it. we get 40Ox400x4O0-s4,- :
100000; and this taken inversely, shows
tho actual reduction of the suns tidal
power due to Its greater distance AS
is 25,5o0i0OO times more powerful than
the moon in producing tides. and. as far
as distance is, concerned, 1t is $4,000 900
times less powerful The final result is
that the effective tidal force of the moon
is about two and a half times greater
than the suns. The actual proportion is
somewhat less than that because we
have used round numbers in the calcula-
RET
distance as compared with the moons.
The law that we have Just applied,
viz: that the tidal force varies inversely
as the cube OF the distance of the at
tracing body, is q very important one
to remember. 1t does not contradict, as
you might hastily infer, the general law
that tho force of gravitation varies in
verse as the square Of the distance, but
on the contrary. 1t grows out Of that law
but 1 have not space here to give a
mathematical explanation of II.
Instead, let us glance at some OF ia
remarkable consequences. II the distance
of the moon from the earth should be
diminished to one-half Of its presen,
amount the height OF the tides would be
increased eight-fold. At every flood tide
the lower parts of New York City would
, be swept with wave. or bore, forty OF
fifty feet in height. H. on the other
hand, the moon should suddenly retreat
; TO twice its present distance, the lunar
! tides would be diminished TO one-eightE
) OF their actual height. and not only New
York bay but nearly all the great har
bors Of the world. would become unnavi
gable for ships OF heavy burden.
II the moon should approach to one
tenth it's present distance (and there d
reason TO believe that It was formerl,
I much nearer than that. its tidal fore,
would be increased a thousand-fold, ant
nearly the whole surface Of the Unite,
: States, from Atlantic coast 70 the Rock,
5 mountains, would be inundated by tida
waves.
If the planet Jupiter should approach
as near as the moon now is, its tida
. force would suffice to raise tidal wave
= In the open ocean ten miles high.
= The story OF the tides, and OF the par
0 that they have played in the evolution
/ OF the earth. the moon. and indeed o
= the whole universe, is one OF the creates
romances OF science.