The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1898-10-02

| could always rise. but it could never
run back. So it was compelled to stay
at the point of greatest temperature.
| When Professor Agassiz unearthed his
instruments. however, he found great
uniformity in the general temperature
of his mine. Evidently the gradual
rise in temperature did not hold in the
Lake Superior district, in which the
| mine is located, as it did elsewhere.
Tie questions now arose: " Why
was this so?'' Did it not have a strong
| bearing on the manner N which the
llearth cooled during geological ages 2
| could not the condition be eX9eri-
mented uDon. and the results be uti-'
lized in some economic manner
| Clearly the condition surrounding the
copper mines in Michigan was the re-
suit of the very low conductivity of the
surrounding rock. Evidently this rock
had not the power OF conducting neat
and cold to the degree manifested by
rock il. other parts of the earth. The
internal heat of. the earth does not rise
up through it as easily, Tor instance, as
does in the rock surrounding the well
upon which Professor Hallock expert
mented near Pittsburg, Pa Just what
is the difference. however. is not so
easy TO determine. and this really is
what Professors Pierce and Wilson of
Harvard are trying to find out. When
they have done so they will have estab-
lished a basis of calculation from which
some new facts may be cleaned, and
upon which some startling theories
may be built
The apparatus in use in its way is as
curious as the information it is intend
ed TO discover AS it stands it is
growth. as various forms were tried
before this one was produced. The eX-
perimenters first procured several slabs
of rock from the very bottom of
the Calumet and Hecla mine. Their
idea was to cool a slab on one side to
the freezing point; to heat it on the
other side at the same time to the
boiling point, that is to say, to the
temperature of live steam, and then,
by electrical means, to measure the
slow passage of heat and cold to and
from the middle or interior of the slab.
Several slabs are placed in the apDar-
atus at once. They are clam0ed be-
tween two platforms of cast iron. The
upper platform holds up a deep tray
which is filed with $50 pounds of ice;
the lower platform supports beneath
it a jacketed cylinder, in which live
steam is kept flowing constantly. These
platforms are not solid; that is, they
are like frames with holes in the mid
die, so that the ice above and the
steam below can come into absolute
contact with the slabs of rock to be
the top of the pile of slabs is freezing
cold while the bottom is very hot. How
is the passage of heat and cold through
the slabs to be measured?
This process involves one of the prin- !
ciples of thermo electricity. 1t must be !
explained that if two metals of dissimi-
lar conductive capacity are submitted |
to the action of heat current of cleo |
tricity will be a result. For instance, |
if short piece Of German silver wire |
and an equal length of copper wire are !
soldered together at one end and then |
if this soldered joint is held in the flame |
of a candle a very small electric cur
rent can be detected at the free ends |
of the wires. Two wires naturally form |
a v, and if several of these VS. are |
soldered together the current gener-
ated will be stronger, just as will a
battery when extra cells are added to |
it. Wires arranged in this manner are |
called thermo-e couples There are other |
however, which, when combined |
in thermo-couples are much more SEN
sitive and hence produce stronger cur |
rents than German silver and copper. |
In Harvard college it was proposed to |
place a small thermo- couple between !
the slabs of rocks being tested The |
couples in this case were made of thin |
fiat strips of platinoid and copper, so |
that the slabs could be pressed tightly |
together. Wires led out from the |
thermo-couples and connected with a |
very delicate recording apparatus 1t |
will be remembered that the under side |
of the rock slabs was hot while the |
upper side was cold. Therefore the |
heat would endeavor constantly to pass |
through the slabs toward their cold |
side. The facility with which it passed