American Agriculturist, March 17,1923 
255 
Make Your Own 
Radio Sets 
Variometer - - _ $2.50 
Varicoupler - - - - 2.50 
Socket V. T. - - - .25 
Rheostat - - . > .25 
Paper Condenser - - .15 
Variable Condenser— 
23-Plate - - . 1.65 
43-Plate - - - - 2.00 
Acme Transformer - - 3.75 
2000-ohm— 
Murdock Phone - - 3.50 
Baldwin Phone - - 10.00 
FREE CATALOG 
Write to Dept. B 
DAVID KILLOCH COMPANY 
57 MURRAY STREET 
NEW YORK 
After 
30 Days 
Free Trial 
bepi. 
rstor — with 
the wonderful 
Self • Balnac' 
IdvBowI. No 
ether like It. 
10 days’ free trial—then, if 
Mtlifled, only 17.60 end > few 
t»8y paynientB — AND— the 
wonderful Belgian Melotts 
Separator li YOURS. 
No Money Down! 
Catalog tells all—write. 
Caution! 
•hows that TibratioD of 
the bowl eauies oreaet 
vxuUt The Uelotte bowl'- 
Is ttlf'ialaneina. Positively 
cannot get out of balance 
therefore cannot vibrate. 
Can’t remix cream with milk. 
Th» Melotts has won tei 
Grand and International 
Pritet. 
Catalog FREE 
Write for new Melotte cat- 
aloR containing full description 
of thle wonderful cream separator 
jmd the story of M. Jules Melotte, 
its inventor. Don't buy any sep« 
erator until you have found out all 
you can about the Melotte and de« 
tails of our 16-year auarantee which 
Runs so easily. 
bowl nins tS imn- 
utee after you atop 
cranking unless you 
apply brake. No 
other separator 
needs a brake. Bowl 
chamber la gorve- 
lain lined. 
U Inflnitetr stronger than anr aap. 
arator aruarantaa. Writ# TODAY. _ 
Hm Melotte Separator. H. B. Babaon, U.S.Mg'^ 
Dept. 30-63, 2S43 W. SSth Straot, Chleage, IH. 
Pay Cash-Save 501 
10 Jewel 20 Year Case 
BRACELET/77££ 
SEND NO 
MONEY 
Overstocked ! 
offerinsr our finest Ladies' Watches below 
w ♦ u®* ® cost. 20-year sruarantee 14 kt. erold-iilled 
1 - u 10-jewel movement, stem wind knd set, 
otyiish octagon case, grold dial; silk grrossrrain ribbon 
■no clMp. Splendid time-keeper. Only $7a45 prepaid, 
ppvp ^oday and get a 20-year gold-filled link bracelet 
Send no money. Pay on arrival. Satisfaction 
guaranteed or money refunded. 
Supreme Jewelry Mfa. Co. 
Pppts 352 434 Broadway New York 
Jor 
JHvV 
'Will Pay for 
f Itself In Two Weeks 
Saves fuel and oil. Saves one man’s 
time on all belt work. Makes tractor 
last longer. Can be installed in twenty 
OuQutes. Lasts for years. Write twUy for free literature*. 
The Pierce Governor Company 
I ANDERSON. IND., U. S. A. 
PATENTS 
Write today for free instruction 
book and "Evidence of Concep- 
r tion” blank. Send sketch or mo- 
oei tor personal opinion. CLARENCE O'BRIEN, 
Patent Lawyer. 904 Southern Build¬ 
ing, Washington, ; . ; D. C. 
The Vacuum Tube 
A Vital Part of the Radio Receiving Set 
When writing to advertisers please 
mention American Agriculturist. 
V ACUUM tubes will 
be used almost ex¬ 
clusively by farmers in their radio 
receiving sets because of their incom¬ 
parable superiority over the simple 
crystal as a detector of radio waves. 
Nor are they complicated in their opera¬ 
tion. The radio enthusiast should be¬ 
come acquainted with them and under¬ 
stand how to conserve and get the best 
service from them. 
All^ tubes are essentially tl^e same in 
principle, although they may differ 
somewhat in appearance, in current 
consumed, and in price. What is a 
tube, anyway? A glass bulb with prac¬ 
tically all of the air removed having 
three important elements enclosed with¬ 
in it. One of these, which usually occu¬ 
pies a position right in the center of 
the bulb, is the filament, and it is the 
same in construction and in operation 
as the filament of any electric light 
bulb. 
The filaments of tubes sold for radio 
use are lighted by batteries whose 
voltage varies from IV 2 to 6. The 
amount of current used runs between 
y 2 ampere and 1 ampere. What is the 
purpose of the filament? In any metal¬ 
lic substance there are an infinite num¬ 
ber of “electrons” or minute negative 
charges of electricity shooting back 
and forth within its boundaries. Now, 
if that piece of metal be heated, 
some of the electrons, will pierce the 
surface and escape. The hotter the 
metal becomes, the more electrons are 
going to escape. 
The Electron Activity 
There are millions of electrons in the 
filament of a vacuum tube. The . cur¬ 
rent from the battery passing through 
the filament, heats the metal and"speeds 
up the electronic activity until many of 
them dart right out. What happens to 
them? Surrounding the filament may 
be seen a spiral coil of wire, the second 
element of the tube, known as the 
“grid.” For the present, let us assume 
the grid coil not connected at all, and 
the electrons passing through its wires. 
The third element of the tube is a 
cylindrical or flattened sheet of metal, 
usually of nickel, which encompasses 
the other two elements. This is called 
the “plate,” and is connected to a 
battery of 2214 volts or more, with 
the positive end of the battery to 
the plate. 
As we noted before, the electrons are 
negative charges of electricity, and 
since unlike electrical charges attract 
each other, the positively charged plate 
draws the negative electrons from the 
filament to it in a steady stream. The 
number of electrons passing over in this 
way depends upon the brilliancy of the 
filament and upon the voltage of the 
plate or “B” battery. 
Let us remember now that between 
the plate and the filament is interposed 
this spiral coil of wire called the grid. 
Suppose the grid is connected to the 
tuning coil of a receiving set. The 
radio waves striking the aerial, set up 
a current rapidly changing its direc¬ 
tion, as we have seen with our crystal 
set. This means that the electrical 
charge impressed upon the grid from 
the tuning coil will alternate from nega¬ 
tive to positive as the current in the 
coil changes its direction. 
With^ the grid charged with positive 
electricity, the flow of electrons from 
the filament will, be slightly enhanced, 
since there will be even a gni’eater posi¬ 
tive attraction from them, represented 
by the positive grid arid positive plate 
combined. But when the aerial current 
changes, and the grid is charged with 
negative electricity. What happens 
then? Like electrical charges, repel 
each other. Therefore the negative 
charge on the grid opposes the flow of 
electrons from the filament, since it 
completely surrounds it. Of course it 
cannot completely throttle the flow of 
electrons, but it reduces the flow in ac¬ 
cordance with the streng-th of the nega¬ 
tive charge. 
Cutting off the passage of electrons 
to the plate will naturally cut down 
proportionately the amount of current 
flowing in the telephone receivers, and 
produces a fluctuation of the telephone 
current in sympathy with the fluctua- 
By BRAINARD FOOTE 
tion of the charge on 
the grid coil. The 
vacuum tube may be seen to have a 
trigger” action, since a small varia¬ 
tion in the charge on the grid controls 
a much larger amount of current 
through the receivers. The operation 
may be likened to that of a simple hand 
valve on a large supply line, where a 
great volume of water may be con¬ 
trolled by an easy movement of the 
valve. In fact, vacuum tubes in Eng¬ 
land are called “valves” because of 
that analogy. 
Gret Good Tubes 
Little can be said about the value 
of a certain tube just from its ap¬ 
pearance, and for this reason the radio 
purchaser should always insist upon 
a tube manufactured by a manufacturer 
of national repute. There is a critical 
value of the amount of air removed, 
and the amount of gas present in a 
tube, which can scarcely be attained in 
manufacture except where the process 
IS carried on in a large well-equipped 
factory. 
The WD-11 tube, which operates on 
a Single dry battery, is unusually scarce 
at present, but a new tube will soon 
appear on the market, which is the same 
in construction and in operation, but 
which fits the standard tube socket. It 
will be known as the WD-12. Another 
^ribe which is now available, is the 
UV-201 A tube, which is similar though 
superior to the old familiar UV-201. 
The UV-201 A requiries but one quarter 
of an ampere filament current, and may 
be lighted from four dry cells connected 
in series or from the regular 6-volt 
storage battery. This is quite an ad¬ 
vantage over the 201 tube, which re¬ 
quires four times as much current. 
However, the 201 A is not quite as 
satisfactory for detection purposes as 
the 200, and will be used more ex¬ 
tensively for amplification. 
Several types of Navy tubes are 
available. The VT-1 operates well as 
detector or amplifier, and the VT-2 be¬ 
ing especially suited for amplification 
where there is considerable volume to be 
taken care of. Both these tubes re¬ 
quire a storage battery for satisfactory 
operation. It may be stated as a gen¬ 
eral rule that no tube should be illumi¬ 
nated more brilliantly than necessary 
for good volume or good regeneration, 
for fear of shortening its life or burn¬ 
ing it out by excessive current. The 
1^-volt tubes should be treated with 
exceptional care in this respect, and 
their filaments should display nothing 
more than a very faint red glow when 
they are operated properly. 
The Valley of the Giants 
{Continued from page 254) 
had come to him. “Sit down, son, and 
tell the old man all about it.” 
Bryce obeyed, and for the first time 
John Cardigan learned of his son’s ac¬ 
quaintance with Shirley Sumner and 
the fact that she had been present in 
Pennington’s woods the day Bryce had 
gone there to settle the score with Jules 
Rondeau. In the wonderful first flush 
of his love a sense of embarrassment 
had decided Bryce not to mention the 
matter to John Cardigan until the en¬ 
tente cordiale between Pennington and 
his father could be reestablished, for 
Bryce had entertained for a few days 
a thought that he could bring about this 
desirable condition of affairs. The dis¬ 
covery that he could not, together with 
his renunciation of his love until he 
should succeed in protecting his herit¬ 
age, had further oper. ted to render un¬ 
necessary any discussion of the girl 
with the old man. 
With the patience and gentleness of 
a confessor John Cardigan heard the 
story now, and though Bryce gave no 
hint in words that his affections were 
involved in the fight for the Cardigan 
acres, yet did his father know it. And his 
heart went out in sympathy for his boy. 
“I understand, sonny, I understand. 
This young lady is only one additional 
reason why you must win, for of course 
you understand she is not indifferent 
to you.” 
{Continued next week) 
• .r" 
MILWAUKEE 
Air Power Wafer Systems 
'lil; 
iBatltRoomJ 
to 
ItvtHc. 
VilK 
■pRESH, tunning water, 
*• wherever needed at a mo- 
men t 's notice, with little or 
no effort! Imagine the con¬ 
venience of a Milwaukee 
Air Power Water System, 
the work you would save, 
the pleasure you would get 
from such a system. 
And, best ofall, the “Mil¬ 
waukee” makes farm life 
easier and happier by sav¬ 
ing money for you. Pays its 
cost by increasing profits 
from cows, hogs and 
poultry. Fresh water, 
no storage tank. Simple, 
automatic. Thousands in 
use. Sizes as low as $125. 
Convenient payment plan. 
Write for 64'Page catalog. 
Milwaukee Air Power 
Pump Co. 
f 13 Keefe Ayo< Milwaukee 
'Rjunning 
Wafers: 
atrecf'^ 
From 
WeJi 
The 
“Pride” 
Send for 
Catalog 40 
A Modem Bathroom, $55 
Just one of our wonderful bargains. Set com¬ 
prises a 4. or 6 foot Iron enameled roll rim 
bath tub, one 19 Inch roll rim enameled flat- 
back lavatory, and a syphon action, wash¬ 
down water closet with porcelain tank and 
oak post hinge seat; all china index faucets, 
nickel-plated traps,and all uickel-platedheavy 
flttings. J.M.SEIDENBERG-CO.,Inc. 
254 W. 34 St. Bet. 7th and 8th Aves. N, Y. C. 
di-rc. SET uivtii 
Simply send name and address. Merely 
Give Away 12 Beautilol Art Pictures 
with 12 boxes of our Famous White Cloverine Salve 
which you sell at 25o each and we will send you 
this Beautiful Dinner Set artistically decorated with 
clusters of roses, foliage and green leaves in their 
natural colors, according to offer in our Big Premium 
Catalogue which you receive with Salve. Millions use 
Cloverine for Chapped Pace and Lips. Bums. Cuts. 
Our Plan Easiest and Squarest. Write quick for pic¬ 
tures and salve. Our 28th year. We are reliable. 
Agents make big money in commissions. 
WILSON CHEM. CO., Dept.D-146. TYRONE, PA. 
THE BEAUTIFUL GLADIOLUS 
Send a dollar for 30 bulbs (will 
bloom this summer), including 
pink, white, scarlet, yellow, crim¬ 
son, orange, rare purple, etc., with 
easy planting directions, postpaid. 
Send Jor free illustrated catalog of over 
one hundred magnificent varieties. 
HOWARD M. GILLET, Gladiolus Specialist 
Box 351, New Lebanon, N. Y. 
$1 Q2S Buys 1 40-Egg Champion I 
I O Belle City Incubator I 
Hot-Water, Copper Tank, Double Walls 
Fibre Board. Self Regulated, a.* 
$6.95 buys 140-Chick Hot-9|K22 
Water Brooder. Or both for only 
EivrossPrapald 
East of the Rockies* 
Guerenteesf. Order aow. Share 
Jn my $1,000 in Prizes, or write i 
for Free Book “Hatching Facts.*' 
— It tells everything. Jim Rohan, Pres, 
neubatorCo.,Boxi47 Racin«,Wis. 
COAL BURNING BROODERS 
Save $5 to $10 on coal burning brooder. Brand new, 
standard make, fully guaranteed. Catalog free. 
CYCLE HATCHER CO., 35 Philo Bldg., ELMIRA, N. Y. 
/ 
