Richmond dispatch. [volume] (Richmond, Va.) 1884-1903, 1898-06-05

also TO be ended if the system is to be OF
practical use. The conductivity Of the
coherer does not, as might perhaps be
expected at first sight, cease with the
| cessation of the electric wave that estab-
| lished 10, but persists indefinitely so long
as the instrument is not disturbed. The
least mechanical shock or vibration, how
y ever. is sufficient 20 destroy it and to
] bring the coherer back 10 its original non
| conducting condition. Hence Marconi pro-
| Vides on the relay circuit an electrical
! Taper, which, by keeping the coherer in
4 a state Of constant vibration, breaks down
! its conductivity as soon as it is estab-
I lished. The method of working is, there
: fore. as follows: II the operator at
! Bournemouth wishes 10 send a message
| 10 Alum Bay, he connects his outside con-
! ductor with his induction coil, at the
same time discOnnecting il from the CO.
herer. Then, by means of the key he
puts his coil into operation for long and
short periods, corresponding TO the dash
es and dots of the Morse code, thus eX
citing in the outside conductor groups of
electric waves. Some Of these fall upon
the outside conductor at Alum Bay, and
convert the coherer there into a conduc
tor; the relay circuit is Immediately
closed, and the Morse instrument begins
10 print. OF course, during the trans
mission Of one dash, the circuit of the
coherer is made and broken many times,
but the printing instrument treats the
quick succession of short currents as a
single long one. The rate at which mes
sages are sent In this way is not very
great, but it is only fair TO say that no
efforts have been made to attain speed.
The intention has rather been to demon
strate that signals can be sent with ac-
curacy and certainty over a considerable |
distance without conducting wires.
A number of experiments have also been
carried out between Alum Bay and ship |
cruising about between the Isle OF wight |
and SWanage. In every case communi- |
cation was easily maintained, whether the |
ship was moving forwards or backwards
or swinging round. Nor was the work
ing of the apparatus adversely affected |
by bad weather. On the contrary II
seemed to act most freely in fog, rain, or
wind, and was at its worst on fine, clear,
still days. These facts suggest that an
early practical application of wireless tele-
graphy might be advantageously found
in the establishment of communication
between the shore and outlying light
houses and light-ships. No really salts
factory way Of attaining this desirable
end has so far been devised. and seeing
that wireless telegraphy can be perfectly
well carried on in tie climatic conditions
which render other modes Of communi-
cation difficult, if not impossible, the ex-
pertinent is surely worth trying
other possible applications of this sys-
tem of teJegraphy might be enumerated,
but Il can scarcely hope TO come into
general use until one difficulty at least,
has been oyercome-that u.s. to insure that
, message is received by the person TO
whom IL is sent, and by no other. Elec-
,ric waves are thrown off in all directions
from their generator so that II man
sets M a. station all his messages can
D. read by any one who cares TO put up
similar station within the limits
o which the waves travel. TWO princi- {
lies may DO employed TO remove or lessen
his Inconvenience. Electric waves. nkS
light waves can be reflected and inter-
.epted hence. g. station could prevent
he emission OF waves in every direction !
tut the one in which lay the station with
Which It wished 10 communicate, and
hus reduce the possible eavesdroppers 10 !
hose lying on the line along which the I
waves were directed. The other principle s
8 that OF syntony. Just as one tuning