Polk County news-gazette. (Benton, Tenn.) 190?-191?, 1914-07-30

mine the rgidity OF the earth are intensely inter-
estng. Science has long needed TO- know the
physical properties OF this globe. 1t is fmpossf
BILE to learn this directly, as the deepest mines
yet sunk penetrate less than two miles below the
surface, distance proportionately no greater
than the thickness OF the varnish on a tWo-foot
globe The interior of the earth Is believed 10
be intensely hot. This theory Is based on the
fact that molten lava is thrown forth by eruptng
volcanoes Also, in descending mine, there Is
rise in temperature, amounting to SO degrees per
mile of descent. II this rate of increase Is con-
slant the temperature at only 100 miles down Is
above the melting point of all substances under
condMions as they exist on the surface OF tue
earth However, despite the high temperature,
the interior of the earth may be held IN soma
state by the tremendous pressure to Whlcn 1t ID
subjected.
Under the now accepted theory Of the celestial
mechanics scientists assume that heavenly
hodv IA held in its course by the attractive force
exerted by the other heavenly bodies on all sizes
of It. In this way Is determined the eartn
course around the sun and the motion oi tue
entire solar system through space Assuming
that the earth Is not solid mass, scentists nave
long struggled to discover how 1t resisted the at
tractiye forces exerted by other planets and stars
whether as a yiscous mass or as perfectly
elastic body.
They have long known that the earth did re-
sist these forces in some degree, me ocean
tides which sweep our shores t"iIo uoi' -
Droof of this 1t has long been known that the
tides are caused by the attraction OF the sun ana
the moon II the earth offered no resistance 10
this attraction, the whole earth would respohu
ouickly to Il and there would be no uues' on
the other hand IL the earth were perfectly rlsiu
body il would resist this attraction compieteLs'
and the tides would reach their maximum helght.
The amount that the tides fall short OF ther
theoretical maximum height would measure the
degree of rigdity which the earth possesses
The next step was to determine the actuai
height OF the tides This long proved the STUN
bling block If shore lines were perfectly stralsht
and the floor OF the ocean perfectly lever, tue
height OF the tides could be measured Directly
hut crooked shore lines and shelving beaches re-
sist the motion of the tides and make IL lmpos'
sible TO determine their height with the accuracy
demanded by science. -.
Sir George Darwin made elaborate experiments
10 determine the height OF the tides, Dut was
obliged to give up the problem In despair rro-
fessor Nicholson solved this difficulty by laying
TWO lengths OF pipe each five hundred rect lons'
and measuring the rise and fall OF the water III
them One length OF pipe was laid horth anu
south and the other length east ana west III
order to measure the tides In both directions
The pipes were buried six feet under ground 10
abtain a uniform temperature.
Az both ends of the pipes tees were inserted
having glass windows for observatory purposes
The pipes were half filled with water ana tne
changes in the height of the water were Obtained
nv measuring through microscope the distance
s.a,~sen n ponter inserted just under the surface
- the water and the image OF the pointer renect
I'D above the water