Evening star. [volume] (Washington, D.C.) 1854-1972, 1898-10-01

platform supports beneath Il a iacketed
cylinder in which live steam Is kent flowing
constantly. These platforms - not solid
that is they are like frames witl- holes in
the middle. so that the ice nbove an, the
steam below can come into ah-olu.c con-
tact with the slabs of rock to ne ,,st.d
Thus II viii be seen that the top 81 the nile
or slabs Is freezing cold while ;he bottom
is very hot. How is the passage of heat
ana cold through the slabs TO -, -1,easilreda
This process involves one OF the prin.
c!ples OF thcrmo-t lectrlcity. II mus. ho OK
planned that If two metals of djsstmi,ar
conductive capacity are submitted 10 The
action of heat n current of electricity will
he a result. For instarCe if n short n,ace
OF German ilve- wire and an egual length
OF copper wire are soidered foeefb,r M o,.,
era; ana then If this soldered point ~ held
IT the hame of candle. very small elcc-
ulc current can be detected at the free
ends OF the wires. The two wires naturally
form a Y. and If several OF these vs. ara
scldered together the current Cen,rat.9 ,,-iII
De stronger. just as win battery when
extra cells are added TO IL. Wires arranged
II, TINS manner are called thermo-cnuples
mere are other metals. however, which
When combined ir tie. moe puul.s ar. r,,i,er,
II ore sensitive anG heLce produce stronger
currents than German silver and conner
IN harvard college II was proposed to
place a Very smell thermo-couplt between
the slabs OF rock being tested TIL. couplas
IN this case were made OF thin fat strtus
ot plStlnoi1 and copper. SO that the slab.
~ fifSStl llSntlE together Wires
LED out from the thermo-couples and con-
Fected with a very delicate recording a ~
paratuS. II viii DE remembered thai th,
under Side of the rock slabs was hot while
the upper side was cold. Therefore the heat
would endeavor constantly 10 pass through
the slabs toward their cold side The facil.
lily with which II passed through would de-
pend directly Oh the conductivity OF the
Slabs In ITS Passage through the sl;, lbs
the heat would encounter the thermo-
couples and In warming them would cause
item 10 produce a small current Of cleo
tricity the strength of which wound de-
pend directly on the amount of heat Thus
the exact conductivity of the rock can
easily be determined
both Wonderful and simple
The apparatus standing cn its table in
Jefferson Physical Laboratory, I'm Cam
bridge, is unpretentious looking enough
The steam, which sometimes escapes from
the Jacketed cylinder, rises aI.d mikes with
the steam of the ice. The recording instru-
ments are on another table. Near by are
the boilers in which the steam IL made, and
small motor attached by belts TO a pad-
die in the ice tray keeps the ice moving
constantly In its compartment. This is
necessary, for if the ice weI-. allowed 10
rest It's cooling effect wuuld nrt he nearly
SO great. great many marines have been
tested IN this machine and test Of the Calu-
met rock is now going on. This rock APP
49," ~ pe d poOf 1lalits al sandstone,
ana strange as IL may seem. ia addition 10
It's low conducting quality Il Is SO very brit
Tie that the very greatest care has to be
exercised in placing il in and IaL.ns il out
OF the apparatus. Its human interest for
the spectator becomes para mount " hen he
thinks that this rock aEproAimately once
lay nearer the earth's center than any
other brought to the surface within n,em-
DRY of man.
By testing the conductiyity OF all the
rock on the globe an approximate. idea may
De gained concerning the ienst,. of time il
mas taken the earth to cool. Thus an ap-
proxtmate statement of ats age other
things considered, may nc made The i'm
mediate utility Of the experiments how
ever, consists in the ultimate calculation of
the conductlvities, and hence the tempera-
lures or rocks and subsuGiayes OF mining
regions. In some places, Notably in South
Attic a. the rise of Temperature below
ground is very rapid. If the true grade MT
Tor all parts of the world can be stated
definitely much unnecessary local EXPERT
mentatlon can be saved. 4 miner would
Know then whether or not RI was feasible
10 carry on extended operations far under
ground. Profs Pierce ami Wilson expect
soon to do this.