Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1939-06-24

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While it is not practical to tell
the specific metal or conductive
mineral present electrically, sur
face geologic conditions suggest the
probable ores to be found.
Any alternating or direct cur
rent means would suffice II We
could touch underground deposits
with measuring terminals. AS this
is impossible, data must be obtained
accurately from the distant surface
The inductive method is the only
one answering this requirement with
a simple field technique.
Such a principle has been long
known. and attempted in the las.
ten years by four and five man
groups using rather heavy power.
Then, however, high frequency d.
rectionaI fields had not been mas
tered and phase difference changes
masked the possible low frequency
results. With such indefinite re-
suits research Jagged while intri-
cate large scale methods were car
Tied on towards a perfected ap-
plication.
Construction and operation of the
present inductive survey apparatus
closely follows the accepted formu
las that were evolved during the
past decade. Many special refine
ments combined with patented ra-
do compass beam Improvements
have been developed through ex-
tensiye laboratory experiments and
field experience. 1t should be not
ed that ordinary radio circuits are
much too erratic to be used.
These adyancements have not /
been in the form Of further com
plications. but rather in a clearer /
simplification of the instruments /
and their manipulation. The final /
result OF this added research is pre-
else equipment that can now be
operated without special training
and at reasonable field cost OF
course some practice Is necessary. j
This is readily gained by few pre-
liminary lines run across known
ore bodies or other conductors.
Such equipment is designed in
portable forms for either one-man
operation, or more elaborate and
deeper reaching units requiring two
handlers. Both of these types use
the same principles, but differ in
applied technicque 1t might be
that associated simple
'esistiVity instruments may be used
,or determining water table and
bedrock depths where geologic }
tructures are clearcut.
Inductive Principles q
The basic foundation of this ]
method is that of electromagnetic ?
comparable to the man i
Ter in which electric current is pro- Y
luced in huge generating plants. I
The means of applying this theory I
o underground exploration Of ore d
leeds equipment Of special and pc r
uliar design. II is essentially .
brought about by a transmitting j
oop Of many turns Of wire placed s
critically and carrying a certain a
frequency current complemented by Z
/ sensitive directional receiving a
oop.
When the earth is flooded with c
| symmetrical radiation field any G
ore body produces a t
counter field OF opposite polarity. a
proportion to the ore masses size. y
iepth and degree Of conductivity. 1
With the horizontal Null" or ST. Il
ence position are plotted across ca
he questioned area.
Spectacular mapping results e
throughout the world include rich q
In deposits in thick Malayan
ungles; hidden galena veins in
he United States Occur d'Alene Il
district carrying $50 per ton silver a
-alues; single California gold peck q
It's yielding up to $500 apiece. 9
Buried treasures have also been I'M :
'arthed with the balanced instru- =
nents: $500 in old coins cached
n cracked bean pot; a fortune
n authenticated Spanish bullion
till under government surveillance.
high Andean burial mound gold.
Accompanying these headline dis
soyeries are hundreds of smaller
pocket, cache and profitable vein