Evening star., 1899-04-15

1.-The receiver consists of a coherer or
tube filled with metallic filings, called by
Branly a 'radfoconductor,' of a model In
vented by NJ. Ducretet This is put in COM
munication on one side with an insulated
conductor of a second tall mast and on
the other side WITH the earth. The end of
the insulated conductor is the collector of
the electric waves. On the other hand, the
cohering tube is placed in the circuit OF a
battery and very sensitive telegraphic
relay The battery current passes In the
electro-magnet of the relay only when the
electric waves. coming through space, trav-
erse the coherer, causing it to become a
conductor
''As In all kinds of telegraphy. each sta
tlon must have both transmitting and a
receiving instrument \ portable receiving
instrument suffices for the reading of the
Hertzian waves signals; and by connect
ing it with a registering apparatus the
message may be printed on band of
paper"
In February the French scientists were
experimenting with sending a message over
a distance of about nineteen miles. Mar
conf had already transmitted a message
over a distance of thirtyone miles.
The Earth's Curvature.
When Marconi began working at his ex-
perinents there were number of diff
cuities to be overcome. One was the trans
mission of the message through damp air,
clouds, &c, another was the transmission
of the waves over such distance as made
the curvature of the earth a barrier to the
course of the waves. He surmounted both
ulIncuIteS, and succeeded in sending mes
SaSe5 through clouds and fog, and il trans
mitting them at distances of thrty-two
miles and more, proving that, to Il consid-
erdbIe extent, at least the problem pre-
sented by the earths curvature could be
solved. The distance to which the waves
can be transmitted is still limited, and even
Marconl mas not claimed that they can be
sent TO any great distcr nee; but il is prob
aDle that, with longer conductors or by
other means, the method will be applied in
ways that will enable the opera tor to trans
NIT messages to a much greater distance
tnan has yet been done.
Narconi found in a series of experiments,
that ne could send messages through any
weather known in England, and has sue
e eeeueo IN transmitting the waves through
logs and clouds to ships at sea, and be-
tween distant points on land. In this re-
Spect the electric wave differs from the
ngnt wave, which cannot pierce the heavy
logs OF the coast. This power of the waves
VIII prove of incalculable value in the life
saving service, and it has already been
used to good purpose in England where a
SHip III distress was rescued by reason of
the transmission of news of her situation
through the fogs to the lighthouse and
thence to land, summoniug heln in time
IN such a case the lighthouse was utterly
helpless.
At the Sea Level.
AS to the curvature of the earth. Marconi
found that If he used a vertical conductor
on a mast of la feet the messages could be
sent without regard to the curvature of the
earths surface. 1t was demonstrated by
Hertz, Righi, PopoF and Lodge that the
transmission of these waves is more readily
accomplished at sea level. 1t is for this
reason that Marconi has done most of his
experimenting on the coast The French
ana Germans, on the other hand have at
.slhpteu, IN the first place. to make use of
the waves as a means ofssending messages
iof the use of armies in the field Last
autumn Marconi succeeded in sending a
number OF dispatches between Osborne on
the Isle of Wight, and the Prince of
" ares yacht which was moving at a
considerable distance at sea.
After he had succeeded in a great nrrn-
Der OF experiments in England, he wanted
10 make severer test of his apparatus
and asked permission of the French gov
ernment to establish station on the coast
near calais. for the purpose of receiving
ana transmitting messages across the chan
hel. His request was denied until quite
recently, when he was allowed to put up a
station on the coast near Boulogne-sur-
Mer. He erected his station on the English
side of the channel on the South Fore
land, IN the county of Kent. The distance
between the two points is about thirty-two
miles The elevation afforded by the cliff
about 400 feet. The experiment proved
successful. and the London Times printed
a dispatch of 100 words tkat had been
transmitted through the air without the
aid OF wires Marconi says that he could
nave sent a message ten miles further or
forty-two miles.
Prevents Sea Collisions
Andre Broca in a recent number of the
Revue Scientifique POINTS out that the
greatest use to which the wireless teIeera-
Ply can now be put is to warn vessels at
sea of the approach of other ships He saws
that with transmitting and receiving in
strume1ts on each ship it will be almost
impossible for collisions to occur Another
use to which IT Is already being applied Is
the similar one in light houses. In times of
storm or atmospheric disturbance or the
Intervention of fOgs or nlists when the
light OF the most powerful refiectors will
not pierce the thick air, the electric waves
VIII De USED entirely for purposes of signal
ing out to sea TO approaching ships If these
Were the sole uses to which wireless telee-
f$phy could be put II would still be one of
the greatest and most beneficent discoveries
of all time.
1t will also be largely used in field opera
tons in sending and receiving dispatches
and information. As pointed out, the French
ana tiermans are now utilizing the waves
Tor this purpose. and the Italians are using
them on their warships for similar pur-
poses. The waves can also be economically
used Tor sending messages between points
on land at not too remote distances, using
V,
y0nd forty or fifty miles.
Nlkola Tesla, who experimental with the
Hertzian electric waves as early as 1893
has called attention to the fact that the
sending of messages over land may be
made very uncertain as the communica-
ttons may be interrupted by placing an in
ductioD coil near of the terminals
Marconi and the other scientists of Europe
do not seem TO fear this difficulty Through
out Europe, indeed, there seems to be but
one opinion of the results obtained by Mar
COM. and, before him, by Hertz Popoff
Righi and others, and that is that a great
advance IN science has been made and a
revolution in the practical use of electricity
has been brought about by a handful of
students within the last decade
Mr.. Tesla and Prof. Oliver Joseph Lodge
of England were both making a series of
experiments along lines that were later fol-
lowed by SignOr Marconi, and which had
been followed earlier by Hertz. Righi and
POpOff. that the so-caled discovery or
invention of Marconi is no new thing The
theory and the law were at least twenty
five years old when Marconi and Righi be-
gan their experiments. But the men who
do something practical with scientific laws
are generally credited by the world with
their discovery. II is probable, therefore,
that Hertz's name will be immortalized by
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