The daily star-mirror. (Moscow, Idaho) 1911-1939, 1922-04-06

We surround the hot wire by a cylin
der Of cold metal which is electrified
positively, the escaping electrons are
attracted to 1t, and the movement OF
negative electrons from the hot wire
to the cold plate creates a thermionic
current. Since then, negative electric
/ ity can pass from the hot wire to the
cold metal cylinder but cannot pass In
the opposite direction, such a lamp,
with cylinder inclosing the filaments.
acts toward electricity as a valve In
q pump acts toward water. 1t allows
flow to take place in one direction
| only. The writer of this article, who
was the first to use in 1904 such an
appliance In wireless telegraphy,
called 1t an oscillation valve, name
subsequently changed to thermionic
valve.
Credit to an American.
''In 1907 an addition was made to 1t
by an American inventor, De Forest,
consisting in the interposition Of a zig
gag of metal wire between the ala
ment and the metal plate Of Fleming
oscillation valve. This addition formed
the starting point for new develop
ments by numerous inventors in Eng
land, America and France, which have
finally given us the remarkable appli-
ance called three electrode thermi-
Onic valve or electron valve, which
cannot only detect but magnify feeble
electric oscillations, and, more impor-
tant still, can generate very powerful
vibratOry electric currents If the cir
cult connecting the outer cylinder to
the fllament contains q battery or dy-
namo creating q steady electric volt
age, and if this circuit Is properly
connected to another circuit joining
the perforated plate or grid with the
filament.
"A Sort Of Lighthouse"
''In this form it is called a trans
hitting valve, and we can by it gen.
crate the very powerful frequency
to and fro or alternating electric cur
rents in an aerial wire which are nee
essary In wireless telegraphy or tele-
phony. These electric vibrations gen
crate the electric waves which travel
away through space from the aerial.
The aerial wire, therefore, resembles
q sort of lighthouse which Is radiating
invisible light. Transmitting valves !
are now made with silica or glass |
bulbs about the size and shape of a
Rugby football. A large number can
be harnessed together so as to gen
crate enormous oscillatory currents.
AT the great Carnarvon wireless
station on the side Of Snowdon, Mar
coni's Wireless Telegraph company
have built valve panel containing
about sixty large valves, which can
put into the great aerial wires cur
rents of three or four hundred am
peres. The electric waves so gene
rated can be detected by suitable re-
ceiving thermionic valves at all parts
Of the habitable earth.
Two Other Methods.
"There are two other methods Of
creating the continuous electric waves
low used in wireless telegraphy. One
II these is by means OF high-fre-
luency alternator, which is compli-
lated kind of dynamo very different
n principle from the alternators used
or producing the low-frequency cleo
ric currents employed in electric
lighting. Machines of this kind are
in the great wireless stations
It Long Island and at st. Assise, near
Paris. Again, there is another method
which makes use Of an electric arc.
me thermionic valve has, however,
reat advantages in point Of first cost
8 against the high-frequency alterna-
or, and 1t il superior to the arc gen
rator because it gives a purer form
+ electric wave, less contaminated by
mixture Of wave-lengths, called
igher harmonies, and has other ad
antages in economy Of power in sig
alinR.
'aThe growth and development of
1e three methods Of electric wave
- namely, by high fire.
uenoy alternators, arc, and thermi-
nic valve panels-will be watched by +