The Banner-Democrat. [volume] (Lake Providence, East Carroll Parish, La.) 1892-current, 1902-02-01
EARTH'S HOT INTERIOR
CAN II BE UTILIZED As A SOURCE
OF PoWER7

OF PoWER2
Professor H1endenhaI Thinks so-Tncress-
ing Temperature With Depth-Modern
Scientists Don't Think the Worlds
Centre 10 Molten Mass.
BY all odds the greatest amount OF
power generated to-day
for Industrial purposes comes from
coal. And inasmuch as the
supply Of that material has
Its limitations and IL likely to be
used up inside Of couple Of centuries.
II not sooner. engineers and philoso-
pliers have begun to cast about for
other resources. The substitutes for
coal which are generally suggested
are falling water, the wind, sunshine
and the waves and tides. But Pro-
fessor T. G. Mendenhall, in Casters
Magazine, makes a somewhat novel
addition 70 the list. Referring to the
interior heat Of the earth. he says that
It lis worthy Of most serious consider
alton as q possible and reasonable
source Of power. Its importance Will
be greatly enhanced when we are able
to transform heat directly into cleo
tricity on q large scale and with econ
omy, avoiding the great waste which
necessarily accompanies the use Of the
steam engine; and this must soon come
about"
TIE earth is globe nearly 5000
miles in diameter, and except for q
thin shell, is probably hotter than any
furnace yet devised by human skill.
Estimates differ as to the thickness
Of this crust. Temperature increases
with descent, IN mines and OIL wells.
at an average rate Of one degree Fab
renheit for every fifty or sixty feet
Assuming that the mean for the
earth's surface Is something like fifty
degrees above zero. the boiling point of
water t212 degrees) would be reached
at O depth Of about 5000 feet. And it
is believed that between thirty and
fifty miles down the heat is sufficient
to melt the hardest known substances
clay, lime. carbon and the like. 1t
would probably not be wide Of the
mark to say that at this distance tenn
peratures Of 5000 and 5000 degrees ex-
list.
The old notion was that the interior
Of the earth was molten, and the phe-
nomena of volcanoes tended to
strengthen that belief. Modern writ
ers, however. incline to the theory Of
potential Elasticity" That is to say,
they think that the heat there is ade-
quate to melt the most refractory
materials, but that melting does not
actually take place owing to the pres
sure of superintendent weight.
A moments reflection will satisfy
one that If this source of energy should
ever become available, 1t would vastly
transcend IN value wind power. water
power. SUI power and tide power.
Even the coal deposits Of the earth.
consumed and Cnconsumed, would be
inconsiderable In comparison. Were
the internal heat drawn of by arti-
fetal neans-the conversion into other
forms Of energy for mans use-the
cooling Of the globe. which is already
going on, would be accelerated. and the
earth would be reduced to the cold,
cead condition Of the moon a little
sooner than otherwise. Thus the very
existence Of the humcn race might
possibly be abbreviated few thou
sand years by climatic changes. Still,
If the great heat reservoir here under
consideration were once tapped In o
satisfactory manner. 1t would be q
practically inexhaustible bank account
to draw upon
Professor Mendenhall outlines no
plan for utilizing the earth's heat be-
yond o suggestion that 1t might be
converted directly into electricity
without the intermediate use Of steam.
There IL much to commend this idea.
II It is necessary to SO down 5000 feet
In order to make water boil. 1t would
DO necessary to go down 1000 more
to generate steam at useful pressure.
say $50 to 200 pounds to the inch.
To be sure, were some more volatile
substance than water employed to pro-
duce the motive vapor. lower tenn
perature would suffice. This in the
principle OF q new motor in Germany
which Just now threatens to work a
revolution in power generation. 1t
takes The exhaust Of conGensing
steam engine. at q temperature of
about 150 degrees, vaporizes Herewith
some sulphur Gioxide, and thus gets
more than q third as much power as
the principal engine develops. This
heat would otherw-e be wasted. A
sulphur dioxide engine might be run
successfully. so far as temperature
conditions alone are concerned. at a
depth Of q mile. which has more than
once been attained by oil wells.
The principle Of the thermo-electric
couple Is very simple. When a change
Of temperature occurs at the junction
Of two slips of dissimilar metals an
electric current Is excited In them.
Many inventors have tried to turn
that phenomenon into account Cla-
mond built up a hollow cylinder out Of
alternate layers of tin and an alloy
containing anthony, and heated the
interior with gas fame around a
perforated earthenware tube. Harry
harrington Cox, Of Hartford. q few
years ago constructed somewhat
similar battery. which could be run
with gas JET and be left alone for a
month at q time. The Postal Tele-
graph tested It and focnd that It would
work q telegraph wire. For some rea-
son these and other thermo-electric
batteries have thus far failed to gen.
crate currents cheaply. but many per-
sons besides Professor Mendenhall ex-
pect to see the secret discovered some
day. Comparatively little more inven.
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