The herald., 1898-11-20

audible, and are not required to be printed
the simple connection of telephone in the
| spark-gap circuit sulfices. The insulation
OF the winding of the telephone must be OF
nature corresponding to the pressure in
the secondary circuit of the induction coil.
An ordinary telephone gives signals audible
at about one metre from the instrument, and
b. the use of loud-speaking telephone the
effect can be increased so as to be clearly
audible in any part of very large room.
When the message is read by the inaudible
system it has the advantage over other sys-
tens of communications by flashes of light
of being as secret as the ordinary method of
telegraphing.
The gentleman who has carried on these
experiments and brought them to such a
successful stage, thus describes his efforts
to perfect his apparatus and work out his
idea OF wireless telegraphy: Il began my
experiments with distance of two metres
between the source OF light and the spark
gap. \ Siemens and Halske arc lamp was
used, taking 10 amperes at Al volts and with
an arc OF l.5 nm, to nm. long. The lamp
was placed behind circular opening pro-
vided with a glass shutter, the rays falling
on the spark-gap through this opening. As
electrodes. two circular brass knbs of %
nm. diameter We're used, connected to the
secondary OF a en-. spark induction coil
with mercury lnterrupter. A fixed spark
gap was used, and the adjustment made by
"A resistance in the primary circuit, as in
all my experiments. With a distance of
nm. between the electrodes, spark oc-
Cured soon as the glass shutter was re-
moved from in front OF the arc lamp. A
coherer placed one or two metres from the
spark-gap responded to the movements Of
the glass shutter and actuated Morse ink
writer As soon, however, as the distance
was increased above two metres the appa-
ratus no longer worked in a reliable manner
The addition of quartz lens in front of the
spark-gap, by means of which the rays were
concentrated on the negative electrode, in
creased the distance over which signals
could be transmitted With lens of en-
diameter and l5 en-. facoi length succeed
ed in increasing the distance to ten metres
| next turned my attention to the material
of which the electrodes were made, and
following The results of earlier investiga-
tions | chose platinum, and covered the
electrodes with this metal in all my further
experiments.
The experiments made with the first in
strument convinced me that | could over
come much greater. distance than sixteen
metres at my disposal in my laboratory.
wherefore secured the use of a hall over fifty
metres long and used much more powerful
lamp. Very satisfactory signals were OBJ
tanned at distance OF fifty metres. Then
extended the distance to POO metres and
>gnaled under poor conditions OF weather
| have not exceeded that distance for the
reason that ! have not been able to get a
suitable space for experiments"
The discovery OF this new means of tele-
graphing without wires has aroused SO
much interest here. where the modest in
ventor has only Just made public the sue
cess OF his experiments, that suitable
place for the extending of the distance be-
tween the protector and the spark-gap will
be obtained, and apparatus of the most
powerful kind made, so as to test to the
fullest extent the usefulness of the discoy.
cry.