The Dawson news. (Dawson, Ga.) 1889-current, 1902-03-12
IMARCONI ON HIS THOD
Famous Electrician Explains His
/ System of Operation.

The Production and Receipt of Wire
less Messages Set Forth Exactly
Hills Are Not Considered Obstacles
How Queen Victoria Used the sys-
tenn.
In paper read before the Institution
of Electrical Engineers Guglielmo Mar
conf explains his system of wireless
felegraphy as follows, says the New
York Journal
When / wish to bridge distances and
Il is not necessary that signals be sent
In one definite direction, l use an ordi-
nary transmitter. 1t is made of two
small spheres, connected by wire, one
vertical conductor of some height, call
ed the aerial conductor" When
wish to direct beam of rays in a Civ
en- direction, use a cylindrical para
bolic reflector placed in the proper
focal line. The system of operation is
simple.
The key is pressed, and the electrical
current is discharged through the spark
gap between the spheres. This dis
charge is an oscillating one. The
spheres and conductor become radi-
ator of electrical waves. By pressing
the ordinary telegraph key at long or
short intervals long or short waves are
made These affect the distant receiver
at long or short intervals, producing
the Morse alphabet of dots and dashes.
One of the most important parts of
the receiver is the sensitive tube, which
is called a coherer or radio conductor.
The only form of coherer / have found
to be reliable for long distance work is
a glass tube of small diameter and four
centimeters long. Two metal pole
pieces are tightly fitted into it. The
space between them is partly filled
with mixture of nickel and silver fill
ings. This coherer is part of a circuit
which contains a local cell and sensi-
tive telegraph relay. The relay works
another circuit operating a 'trembler,"
''tapper" or "decOherer'' and record
ing instrument.
Normally the resistance Of the filings
as great, but under the waves they
cohere and become comparatively q
good conductor. This allows the cur
rent from the local cell to operate the
relay. One end of the tube is connected
with the earth, the other with YER
teal conductor.
II reflector for special direction
transmission is being used at the send
ing station, q short strip of copper is
fixed to each end Of the glass tube in
the receiver. These strips must be eX-
aetiy proper length. otherwise they
will not be In tune, or syntony, with the
transmitted waves. All of the electro
magnetic apparatus in the receiver is
shunted by noninductlve resistances in
such a way that there is no sparkling at
contacts and no jerks caused by the
local battery. or cell, near the coherer.
The 'tapper" and Geographic instru-
ment. If not properly shunted, produce
disturbing effects. Small choking
coils" are put between the coherer and
the relay. They force the waves to
traverse the cOherer. The oscillations
or waves on the copper strips cause the
metal filings to cohere and become
conductor. The ''tapper" shakes the
filings apart, breaking the circuit. The
practical result of this is that the dots
and dashes come just as they are trans
mitted and are so recorded by the mixer
in something Of the same fashion in
which Geographic instruments years
ago used to print upon paper tape.
With vertical wires it is easy to rcdch
q station screened by hill or curva-
ture of the earth. In such cases 1t
seems to be marked advantage If the
aerial conductor is thick o" If capac-
aty area be placed at the top of it.
am rather doubtful as to the cor
rect explanation of this effect. as there
ts little doubt of the complete opacity
10 electric waves of a hill three miles
thick or of several miles of sea water
1t may be thaS tie oscillations ar"
transmitted TO -arth by the grounded
wire and follow the earth's surface I'M
II, they reach tie earth wire of the re-