ican Agriculturist, January 20,1923 
The Simplicity of Radio 
{Gontmued 
ing the number of turns on the coil 'is 
known as “tuning” and means a change 
in the inductance of the aerial system. 
Few Parts Need Be Published for 
Crystal Set 
Few parts need be purchased for so 
simple an outfit as given in Figure 1. 
A half-pound coil of No. 20 enamelled 
magnet wire wil be sufficient for the 
coil. For connections and incidentals, 
a half-pound of No. 18 bell wire should 
be purchased. Then there are needed 
five binding posts, one small brass 
angle, a strip of brass about four inches 
long and an inch wide, two small rub¬ 
ber composition knobs with threaded 
bushings for an 8-32 screw and a card¬ 
board tube about SV 2 or 4 inches in 
diameler and 4 inches long. An oat¬ 
meal or salt box fills the bill exactly. 
Figui'e 1 is self-explanatory as regards 
from page 57) 
over, the antenna is in reality a true 
protection to the house, as much as 
lightning rods are a protection to the 
barn. Small static changes will leak 
off and may sometimes be heard crack¬ 
ling through the lightning arrester dur¬ 
ing a thunderstorm. This prevents the 
accumulation of a heavy and dangerous 
charge of electricity over the house. 
Obtaining a Good Ground Connection 
Sometimes it is difficult to obtain a 
good ground connection on a farm 
where the house is not piped. In that 
case, good results may be obtained in 
several ways. If there is a fairly long 
chicken wire or barbed wire fence near 
the house, the ground wire from the 
lightning arrester may be attached to 
this. Outside piping connected to the 
well is very satisfactory fur this pur¬ 
pose. In the absence of any of these 
Ligl?ln/ng 
Receiving , ' 
Seh 
Wdfer 
Pipe or 
Radiator 
Ground 
CtafTip 
Aurlol and 
Ground *14 
.Single or Stranded 
Copper Wire. • 
Insulapjr-Eflch End 
FjG,yfter S 
0F 
Diagram of Arrangement for Bringing Aerial Indoors 
the arrangement of the parts on a 
wooden base, and the connections. The 
insulation is removed where contact is 
made, as indicated. Two and one-half 
inches of the tube are wound tightly 
with the enamelled wire, securing each 
end in a small hole with one or two 
twists. The brass strip is cut in half 
lengthwise, and one strip is cut and 
bent to form the tuning arm and 
mounted in front of the coil. The lat-' 
ter is fastened down to the base with 
the aid of a wood screw and washer at 
each end. One rubber knob is mounted 
to form the handle of the tuning arm 
or “slider” and an arc traced u^on the 
wire by the rounded end. Sandpaper 
is then brought to use in cleaning the 
surface of the wire so that the slider 
may make contact with one end to the 
other, care being taken to brush out 
small copper particles from between 
the turns. 
Making’ the “Cat-Whisker” Detector 
A spring clip for the crystal is bent 
from the other brass piece and held in 
place by a screw. A piece of the enam¬ 
elled wire is scrhped clean and sharp¬ 
ened at the end by a sidewise cut with 
a pair of shears to form the' “cat- 
whisker” of the detector. Good mount¬ 
ed crystals may be purchased for 35 or 
50 cents, and should be handled so that 
the fingers do not come in contact with 
the mineral itself. Natural oil from 
the hands soon destroys the sensitivity 
of a detector crystal, although it may 
be cleaned if n^essary with wood alco¬ 
hol and a clean cloth. The phone con¬ 
denser appears in various forms, and 
any condenser stamped with a capacity 
of about .001 is suitable. A brass ma¬ 
chine screw, 8-32 in size, is employed 
to support the cat-whisker, the other 
rubber knob screwed on as a handle. 
Figure 2 shows the antenna, lead-in 
wire and ground. The lightning ar¬ 
rester is required, and may be mounted 
upon the window frame or on a board 
near the window. When this is prop¬ 
erly installed and the set connected, 
the agent of the fire insurance company 
holding the policy on the house should 
be notified. He will then either inspect 
the installation himself or have it in¬ 
spected, and a notation will be made 
upon the fire insurance policy granting 
permission for the radio outfit. There 
IS no change in the premium rate when 
a radio is properly installed. More- 
possibilities, a piece of insulated wire, 
about No. 14 or 16, and just as long 
as the aerial wire, may be run out 
directly under the aerial, lying directly 
on the ground. Where it* is necessary 
to use an outside ground, an additional 
porcelain tube should be inserted to con¬ 
duct the wire outside. If it, is not de¬ 
sired to drill holes in the window frame, 
the tubing may be placed in a narrow 
board which will fit the window frame 
and upon which the sash may be closed. 
Some care is needed in the selection of 
the headphones. A pair of phones hav¬ 
ing fair sensitivity may be purchased 
for about $5.00. Since the phones will 
be used later on in better receiving 
equipment, however, it is wise to pay 
enough more to insure long life and 
maximum response. Therefore, it is 
well to pay about $8.00 for the tele¬ 
phone receivers. If there is no radio 
supply store nearby, recourse may be 
had to the mail order firms, practically 
all of whom carry reliable radio appar¬ 
atus of every description. 
Interpreting the Schematic Diagram 
Beneath the pictorial sketch is the 
schematic diagram as used in most 
radio “hook-ups.” The beginner should 
commence at once to correlate the two 
forms of diagrams, comparing the ac¬ 
tual instruments with their schematic 
symbols which will be used later on in 
(Continued on page 63) 
The Valley of the Giants 
(Coyitimied from page 58) 
the end, and by using the haft to cling 
to, crawled toward the rear of the load 
and looked down at the caboose coup¬ 
ling. The top log was a sixteen-foot 
butt; the two bottom logs were eight¬ 
een footers. With a silent prayer of 
thanks to Providence, Bryce .slid down 
to the landing thus formed. He was 
still five feet above the coupling, how¬ 
ever; but by leaning over the swaying, 
bumping edge and swinging the axe 
with one hand, he managed to cut 
through the rubber hose on the air con¬ 
nection. “The blamed thing might 
hold and drag the caboose after I’ve 
pulled out the coupling-pin,” ^he're¬ 
flected. “And I can’t afford to take 
chances now.” 
{Continued next week) 
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FOR 50 CENTS 
AS a part of our broad policy of service 
ilL to readers, we now offer you a 
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You may be Hurt or Killed in a 
Train or Auto Accident 
Tomorrow 
This Tells You What 
the Policy Will Pay 
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MAIL THIS COUPON 
AT ONCE 
TO AMERICAN AGRICULTURIST, 
461 Fourth Avk.,,Np;w York City. 
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Signed ... 
P. O . 
R. F. D. No . 
State,. 
yjy age i.9. 
(Youmust be over 16 and under 70) 
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