Evening bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1895-1912, 1900-08-24
Hertzian Waves.

Hertzian Waves.
We now come to the celebrated sys-
TEN of wireless telegraphy by means
of Hertzian waves. In 1867, Mr.. Clerk
Maxwell put forward the theory tia.
waves of light are not mere mechanical
vibrations Of the ether, but are electro
undulations. Although Max
well practically proved his case by
reasoning,it was given 10
subsequent experimenters to practl-
cally demonstrate the truth OF this far
reaching theory. The number and
nature of these experiments,
and the consequences Of the theory.
have combined to make the subject OF
the most fascinating study
opened to us by modern science. H.
1883, Hertz established the most con
vincing experimental proof of Max
wells theory. and succeeded In produc-
ing electromagnetic waves in way
which enabled him to show that while
they were much larger than ordinary
light waves, they Travelled at the same
speed, and werecapable Of being re-
fected, refracted. polarized, etc. Be.
fore proceeding further with the sub
ject Of electromagnetic fluctuations, II
will be well to consider how these I'M
dulations differ from the puisations of
the magnetic field employed in mag
netic telegraphy.
When an electric current flows along
a wire, the space around the wire he
comes magnetic. II an electric current
increases In strength the magnetic
field around It also increases in
strength the magnetic field around il
also increases. the magnetic force err
larging from the conductor outward,
like the ripples on the surface of 4
pond. But as the current Is decreased,
the magnetic field returns back and
closes up on the conductor. These ate
the magnetic pulsations or ripples used
In magnetic telegraphy. But II for
currents slowly waxing and waning we
use electric oscillations or pulsatiuns
of excessive rapidity, part of their
energy radiates off into the ether as
electromagnetic, waves, and only pat
returns back. It is these electromaE-
netic undulations that Hertz expert
mentally showed to be identical with
light.
coherer tn. Secret.
There are many instruments sensi-
tive to these Hertizian waves, but the
most sensitive of all is what Is called
a coherer. This merely consists of q
silver wire cut through at one point
the gap being filed with a mixture
OF metallic filings-preferably nickel
and silver-and the whole enclosed in
vacuous glass tube. In the normal
state Of affairs, this coherer offers i
practically infinite resistance to The
passage of an electric current. When
however, electromagnetic waves fall on
II, It's resistance Is decreased TO sucl
an enormous extent that 1t allows Z
battery connected with II to send Z
sufficiently strong current through thu
coherer to work Morse telegraph in
strument.
Thus 1t Is seen that the essential Re
quisites for Hertzian wave telegraph!
are. an electric cdrrent oscillating will
excessive rapidity in order to Set II
electromagnetic waves in space, and !
coherer sensitive to these waves. TIL
latest and In fact the only commercial
" successful system OF telegraphy b,
Hertzian waves. is that brought on
by Signor Marconi. The essential tea
ture OF his system Is an elevated yer
teal wire at both the transmitting an
receiving ends. The exact theory % tn
vertical conductor Is not yet fully I'm
derstood. but II Is known that Ion
wire OF some sort Is an essential part
the oscillator required to get M III
excessively rapid surglngs require,
All that is known aboutthc vertici
wire, Is that other conditions bcln
constant, the distance that can he sil
nailed over is proportional to III
square root OF the height of the wir'
Efficient in Any Weather.
This system OF telegraphy is eftlc!er
under all conditions of weather, and
especially adapted for long distanl
transmission. The only objection WIS
lattend sits use Is that the arrangemen
are not synotic. That is to say al
cohered will respond to any source
electromagnetic waves. II Is no
claimed that improvements have bee
made which do away with this OHIO
ton, but the knowledge Of how this
done is not yet public property.
, should be noted. moreover. tn
Hertzs original receiver could be syI
tonized with the oscillator, but 1t WI
. not sufficiently sensitive to be Of u
for long distance telegraphy. so ia
|, the greatest distance that has be-
telegraphed over by Hertz.an waves
about one hundred miles, The Marco
: system is In use in a great many place
and 1t is expected that an instAllatit