Frostburg mining journal. [volume] (Frostburg, Md.) 1871-1913, 1893-08-26
Jumped in the Dark,

A country physician was driving,
late one night, over strange road. A
violent rain had been falling and the
highway was badly washed. Presently
his horse made leap and crashed
through what seemed to be the upper
branches of tree, taking the gig with
him. Half mile further on he made
another jump; there came 4 crash and
ehiver, the gig reeled over another tree,
poised for moment on one wheel, and
righted itself as the horse resumed his
trot.
By this time the doctor knew he must
be near river with high banks for he
could hear the water roaring on the
rocks below. Now the horse came to
dead stop and refused 10 GROSS the
bridge. The doctor urged him for
ward and he took few steps only to
move back in his tracks. This was
twice repeated. Finally vexed at such
unusual obstinacy the doctor struck
him with the whip. The horse squealed
with disgust, shook his head, advanced
as before and backed again.
Now, at last, the doctor alighted and
went forward to reoonnoitre. This was
what he saw. The flooring of the bridge
had been completely swept away by the
flood. Nothing was left but the sleep.
ers running from bank to bank, and it
was on one Of these that the horse had
walked out as far as he could with safety
to the gig and its occupant.
The distractions which the roadster
had jumped were brush fences put up
to stop travel on the highway until the
bridge could be repaired,
Internal Heat of the Earth.
The existence of volcanoes, geysers
and hot springs irregularly scattered
over the whole surface Of the globe
and continually ejecting molten rock,
ashes, mud, steam or hot water is an
obvious indication Of some very wide
spread source Of heat within the earth,
but of the nature or origin of that heat
they give little positive information.
The heat thus Indicated has been sup
posed to be due to many causes, such
us the pressure and friction caused by
contraction of the cooling crust, chem
ical action at great depths beneath the
surface, isolated lakes of molten rock
due to these or to unknown causes, or
to molten interior, or at least gen.
eral substratum of molten matter be-
tween the crust and q possibly solid
interior.
The two first causes are now gener-
ally admitted to be inadequate, and
our choice Is practically limited to one
Of the latter.
There are also very important evil
dences of internal heat derived from
the universal phenomenon of a fairly
uniform increase of temperature in all
deep wells, mines, borings and tunnels.
The increase has been usually reckoned
as one degree Fahrenheit for each sixty
feet of descent, but recent very care
full estimate by Prof Prestwitch, de-
rived from the whole available data,
gives one degree Fahrenheit for every
47.5 feet of descent.
1t Is a curious indication of the uni
versatility of this increase that even in
the coolest parts Of Siberia, where the
soil is frozen to depth of 62O feet,
there Is a steady increase in the tenn
perature of this frozen soil from the
surface downward.
Much has been made by some writ
ers of the local differences of the rate
of increase. varying from 1 degree in
% to l degree In 90, and also of the
fact that In some places the rate of
increase diminishes as the depth be-
comes greater.
But when we consider that springs
often bring up heated water to the sur.
face In countries far removed from any
seat of volcanic action, and the extent
to which water permeates the rocks at
all depths reached by man, such diver
gencies are exactly what we might ex-
pect.
Now, this average rate of increase, If
continued downward would imply
temperature capable Of melting rock
ut about twenty miles deep or less.