Evening star., 1927-10-23

Plans looking toward offsetting the
shortcomings in radio reception
through better broadcasting will sug-
gest to the progressive radio owner
possibilities in the line of compensat-
ing for poor broadcasting through i'm
proved operation and conditioning of
the receiving set. Compensation is a
rule that works both ways.
Broadcasters have overcome a NUM-
ber of difficulties for radio owners
through increasing power. There is
less fading to contend with and radio
lists are enabled to enjoy good recep-
ton even il their batteries or tubes
are not in the best of condition. There
are, however, numerous instances
where broadcas sting is not at its best,
and where this is the case the radio
owner should look to the facilities Of
fered by his own set and its acces-
sories to overcome the difficulties.
He can soften reception through de-
tuning. This is simple process OF
turning the tuning dials little oil the
true setting for the respective station,
and is a plan which many radioists
know about, but often overlook. II
there is too much volume he is able to
cut out a stage Of audio and thus re-
duce the ampliflcation.
It is not generally recognized oy
radio owners that even though
broadcaster may take special precau-
tions to have everything in the most
satisfactory order, there are many rae
tors beyond his immediate control.
Weather conditions may be adverse
to radio broadcasting in the territory
near the studio, yet out where some
set owner is getting signals the ar
may be cool and crisp. 1t is not
possible for the broadcaster to meet
all conditions where they change so
rapidly and where the spread of the
signals is 50 extensive. This part OF
the Job Ia left to the radioist who has
within his power equipment and con-
troIs suficient to enable him to adjust
the sensitivity of the set to meet the
efficiency of signal transmission. i.
Radio Waves Penetrate Rock.
Recent tests, conducted by the
Bureau of Mines In Colorado metai
mine. indicate that radio waves Will
penetrate 500 feet or more OF rock
strata. Preliminary experiments were
observed by DIR. A. s.. Eve, director or
nhvsics at McGill University, Mon
treal. Canada, who is conducting a
study for the bureau of the possibil.
tiles of various methods of geophysical
prospecting for the location Of mineral
deposits.
The experiments participated In
were carried out with a superhetero'
dyne receiver of nine tubes in the
mine Of the American Mining Pros
pecting Co., at Caribou, Colo. The
first test was at depth of 220 feet
where, by means of a loop. a strong
and clear reception was obtained or
musical concert broadcast by Denver
station, so miles distant. The evidence
pointed strongly to the conclusion that
this clear reception was due to the
penetration by the radio waves OF the
solid rock strata, although there was
remote possibility that the reception
was obtained through shafts and
cross-cuts, although the loop did not
point in that direction. The neares,
metal conductors, iron rails, were 81
feet away.
The next experiments were con
Quoted at a depth of $50 feet, wher
"mushy" reception was obtained from
the Denver transmitter. This type Of
reception was. however, as good al
could be obtained above ground a
the time, the night being unfavorable
This series of tests was conducted al
the end OF a cross-cut reached after
many turns, and 200 feet from the
main shaft. A pipe came down the
shaft and followed the tunnel up to 81
feet from the point Of observation.
Following previous experiments con
Quoted by the Bureau Of Mines neal
Pittsburgh, Pa, 1t was at first con
cluded that radiation and induction
would penetrate rock for considerable
| depths. but subsequent investigations
showed that in every case the trans
ference OF radiation was by some con
ductors such as electric wires, pipes
or rails.
It is possible that at Caribou the
radio waves excited the conductors In
the shaft. and that these In turr
excited the rails and pipes, which
brought the radiation to within 20 O,
30 feet Of the experimenters, and tha