New-York tribune., 1899-04-16
WIRELESS TELEGRAPHY.
DID TESLA ANTICIPATE MARCoNI IN
THIS WORK?
FOUR OF THE BEST KNOWN sYsTEMs-THE vER-
rIcAL WIRE AND AERIAL PLATE.

Marconi's success in sending messages across
the English Channel has given rise to an eH-
tended and animated discussion Of other sys-
TENS of wireless telegraphy
At the present time there are at least four
clearly recognized methods OF sending electric
signals without metallic connections between
stations Mr. Preece tried what is called IN
duction." He laid mile Of wire along the
ground the mainland and another mile OF
wire parallel with the first, on an island mile
away A message sent through one circuit was
caught by Induction in the second. very mucn
as a telephone message was at one time over
heard by users of parallel telephone wire Al
though DR.. Lodge and some others think that
this system may yet be developed further MI.
Preece himself has practically abandoned 1t as
unsatisfactory and unpromising.
Secondly there is what is known as the Hertz
wave method BY well-known apparatus-an
induction COLA stream Of sparks Is produceu
at a gap in an electric circuit. electromagnetic
waves are thrown out sidewise from the gap
These can be picked up at a moderate distance
by means Of one of the many sensitive devices
we'll known to expert electricians. Marconi uses
a bit of mechanism called the "coherer. whlcn
was invented by Branley. He connects coherer
a local battery and an ordinary telegraphic
sounder with short wires and whenever Hertz
waves from a distance fall on the coherer. the
latter permits the local current to pass anu
ectuate the sounder The only original part oi
Marconi's work. apparently. was the aooi,ioh
TO the coherer Of an automatic Taper WHICH
caused the particles Of metallic dust IN the CO.
herer to fall apart and break the connection
when no waves were coming from space 10 az
feet II.
Thirdly there is what is called the conouc-
ton" method 1t has been proposed 10 drop
wire from the transmitting station into the
earth or sea, and a similar wire from the re-
ceivng station TO the same conducting medi-
um, and let the message go through this AS
yet this plan has been tried only mperfectIy,
and on a small scale. Silvanus p. Thompson
once offered to the British Government to es-
ablish communication between London and the
Cape of Good Hope in this manner. II he could
have $4,000 with which to procure and install
the necessary instruments.
Fourthly. an important modification of the
last mentioned plan has been suggested by Mr.
Tesla who has experimental with all of these
systems and who has gone rather further into
the theories involved than many others whose
names are often heard in connection with wire
less telegraphy. In a lecture which he delivered
in St Louis in February. 1893. Mr.. Tesla rough
ly outlined a plan that should utilize the earth.
but should supplement the apparatus which
produced his current with a short conductor
that ran up a pole into the air for a short dis
tance and terminated in a fiat metal plate.
This plate would correspond to the Leyden Jar
or condenser" of the laboratory The quality
Of the current sent into the earth would be ar
fected in certain ways by such an attachment
The nature OF the influence thus exerted may
be inferred from one Of Mr. Tesla's most famous
Inventions the Tesla coil" This consists OF a
condenser and an induction coil in combination.
An induction coil it will be remembered, is
made of two carefully insulated coils OF wire,
one short and coarse, and the other long and
fine If a current Is sent through the coarse
wire, primary circuit" 1t induces another.
possessing less quantity but higher pressure, in
the fine wire or secondary" circuit. Now. Mr..
Tesla's scheme was to take a condenser. pour
his current into this first. All 1t to overfowing.
and then let the escape lead 10 the primary cir
cult Of an induction coil. The current in the
secondary would then possess new characteris
tics 1t would be made up Of abrupt vibrations
OF almost inconceivable frequency and penetrat-
ing power. In the production Of X rays and
many other kinds Of electrical work. the Tesla
able instrument.
or course since the st. Louis lecture was de-
livered Mr.. Tesla has perfected several other
devices notably his ''osciator" which increases
the possibilities Of potential" voltage" pres
sure" or whatever else one may choose TO call
the penetrating quality of electricity This and
other instruments which he has invented in
crease the efficiency of the scheme outlined
more than six years ago but they do not alter |
or add essentially to the principle.
1t is a singular fact that when Marconi first |
began TO work with Hertz waves he did not |
use any vertical wire running up pole and |
terminating in a metallic plate. But as soon as
he added that feature to his equipment, he was
delighted to find that he had improved it's |
working qualities. In a paper which he read |
before the Institute Of Electrical Engineers In |
London last month Marconi said: With other |
forms OF Hertzian transmitters and receivers, |
hnd II quite impossible to obtain any results IL |
a hill. mountain or large metallic object inter |
venes in any way between the two stations. |
When the vertical wire system is employed, II |
becomes easy to telegraph between positions !
screened from each other by hill or the curva- |
ture OF the earth. am rather doubtful
as TO the correct explanation Of this effect. as
there can be very little doubt as TO the COM
plete opacity OF a hill three miles thick, or say, |
several miles Of sea water. A way out Of the
difficulty may be arrived at. II we suppose that
the electrical oscillations transmitted TO the
earth by the earth wire from the induction
coD travel along the face of the earth. reach
the earth wire Of the reactng instrument, and
by travelling up this wire 70 the coherer bring
about its action"
II this explanation be approximately correct,
It would seem possible. not TO say probable. that
two sets Of vibrations excited one at the
spark gap. traversing the ether, and the other
sent down into the earth. The former may be
discernible at a short distance. but the latter
al a much greater one. Thus Marconi appears