New-York tribune., 1902-03-03

but less advantageousy. The natural rate.
however. be altered by varying the length
of the wire. or by subjecting the instruments
in the circuit to certain notifications.
Hertz showed that if near a short circuit OF
wire in which violent and rapid oscillations
were taking place a second circuit be held. the
latter would be similarly disturbed. But the
sympathy would be much ivelier II the natural
rate of vibration the same in the two cir
cults This phenomenon is called electrical
resonance" Mr. Marconi makes use Of that
principle when he tunes his receiving circuit
to accord with the sending circuit. As matter
Of fact. he has two circuits in his sending ap-
paratus, and two a his receiving station all
OF which need to be thus brought into tune
in order TO give the best results, Reference 20
the accompanying diagram. which roughly IL
lustrates the arrangement at the transmitting
station, will help to Fan understanding OF the
process
Those who are at all familiar with ths mech
anism OF the earlier methods of Mr. Marcon will
have no difficulty in following the description
The battery is shown AT A and the operators
key at b. These are connected with Undue
tion coil &C.. which intensifes the curren, and
sends II into the circuit d D d. The latter
may be called the transmitting circuit. 1t Is
broker at f. where series of sparks leaps
acrosS from one brass ball to another The i'm
perfect barrier presented here imparts to the
oscillations in d d d d an enormous frequency,
Another instrument in this circuit is cont
densF CF). At @ Is shown only the lower part
of tlh famous vertical wire. in which similar
oscillations are produced and from which
radiate Sideways into space the so-Called Hertz
waves. The frequency of the latter depends on
that of the former. a few turns made II
the vertical wire at L, for purpose about to
be explained. The extreme lower end OF the
wire GI) is not attached TO anything.
The oscillations get out OF d d ID into q
in the following manner: Two distinct coils of
wire q and X combined in such a way
that a sympathetic current is excited in the
latter by the former. The coil l forms a part
of the transmitting circuit. while the upper end
of * can be adjusted to come in contact
with any Of the conVOlutions of @. Thus, K.
whose lower end is In the earth at NJ, is praCti-
cally a continuation of the vertical wire. BY
shifting the point OF contact between the upper
end of and the lower part of the vertical wire
the length Of the combination may he either in
creased or lessened. Since the natural rate OF
oscillation depends length. the adjustment
long as ID ID ID ID. The two then oscillate in
harmony Similar steps taken the re-
ceiving station. 1t should be added, however,
that this plan represents only one of several
methods of tuning but II is perhaps the most
ineligible.
Mr. Marconi said yesterday that the exact
frequency of the oscillations in the Poldhu
transmitter and the receiving instrument the
Philadelphia was millions a second" but Just
how many millions was professional secret.
He not prepared to say just how many
tuned" circuits could be worked simultaneously
in the same neighborhood precisely how
close one frequency could safely approach an
other without sacrificing secrecy. In addition to
privacy and freedom from interruption there
another advantage in tuning the sending
and receiving apparatus. greater distance
could be covered thus than otherwise The chief
explanation of his recent gain in distance. how
ever, was the greater power employed to operate
his transmitter. He secured better results after
he connected both sets of instruments with the
ground than he did at the outset and he was
convinced that the earth was to some ex-
tent a conductor of the waves. Concerning the
exact combination of instruments a sending
station he was reticent. The diagram does not
show these with precision. 1t merely illustrates
the means OF tuning" Mr.. Marconi still uses
the coherer for receiving instrument, 10 some
extent. but not exclusively. The other ap-
paratus for that purpose, however. he was not
ready to describe yet.