Democratic messenger. [volume] (Snow Hill, Md.) 1869-1973, 1922-04-29

we surround the hot wire by cylin-
der Of cold metal which Is electrified
positively. the escaping electrOns are
attracted 10 II. and the movement 81
negative clectronS from the hot wire
to the cold plnte creates thermlonic
current. Since then negative electric
iiy can pus> from the hot wire Ia the
cold metal cylinder hut cannot pass In
the opposite direction. such a lamp.
with cylinder inclosing the iilaments.
nets toward electricity a. a valve in
pump acts toward water. II allows
n flow tu take pac" IN one direction
only. The writer nf this article. who
was The first 10 u>e in 1894 such an
appliance in wireless tclcgraphy.
called it an oscillation valve. name
subsequently char.ed g." therminnic
valve.
Credit TO an American.
"ln 1897 an addition was made 10 Il
Is uu American inventor De Forest.
com i~tiu. iu The iuterpo>li"n "f zig
"a of mctal wire between the fila
mcu' and the uetal plate Of a Fleming
oscillation valve. THIS addition formed
tile >tariin. point for new develop
inent> by numerous inventors i'll Eng
land. America and France. which have
finally given Us the remarkable appli-
ancc called "a three elecirosie thcrmi-
onic valve or elcrtr"n valve. which
cauuol only detect tut magnify feeble
electric oscillations and. more impor
tant sin can generate very powerful
vihratory electric currents II the cir
cult connecting the outer cylinder e.
the iilamout contains q battery ar dy-
name creating a steady electric volt
age. and ii this circuit j. properly
connected To- another circuit joining
the perforated plate or grid with the
filamcut
"A Sort OF Lighthouse"
ain this form il i called trans
mitting valve. and We can by II gen
crate the very powerful high-frequency
t. AMI fro or alternating electric cur
reniS IN nm aerial wire which are nee
c>>ary IN wireless telcsraphy or tcle-
phanV. These electric vibrations gen
crate the electric waves which travel
away through space from the aerial.
The aerial wire. therefore. resembles
a sort ~ lighthouse. which l. radiating
invisible light. Transmitting valves
arr now made with silica or glass
hulb> about tie, size and shape of a
Rugby foothall \ large number can
he harnr>Sed together 81 aS To gen
era,v enormous oScillatory currents.
NJ the great Carnarvon wireless
station on the side of Snowdon. Mar
cons Wireless Telegraph company
have built valve panel containing
about sixty r.. valves. which can
nut into the great aerial wires cur
rents nf q re-. ar four hundred am
per,S. The electric waves 81 gene
rated eau bc detected by suitable re
ceiv.n. thcrmionlc valves nj all parts
II the habitatle earth.
Two Other Methods
There are two other methods a.
creating the continuous electric waves
now used in wireless telegraphy. one
~ these i hy means ~ high-fre-
auency alternator. which i Il c"mpli-
Gated kind Of dynamo very different
III principle from the alternators used
Tor producing ,i,.. low ir,SIur",. -',-' .
tric currents employed in electric
lighting. Machines of this kind are
Installed in the great wireless stations
NJ Long Island and at 80. ASsise. near
Paris. Again. there is another method
which makes use If an electric arc.
The thermi0nic valve has. however.
great advantages in point If first cost
a. against the frequency aiierna-
tor and il i superior to the are gen
orator because il gives "a pur"r form
" electric wave. less contaminated by
n mixture Of wave-lengthS called
higher harmonies. and has ether nj
vantase> in economy II power In sig
mailing.
The growth and development ~
,hs. thr-,. methods NJ electric wave
generation namely. by high FIRE
0uencv al,eruators. are. and thersni-
onic valve panels will b. watched by
exr~.rtS with great Interest