The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1900-02-10
WIRELESS TELEPHONES.
A New Development of the Marconi
System.


LEXINGTON, KY, Jan. 27.-The eX-
periments being conducted in wireless
telegraphy at the State College of Ken
tuckv by Professor Charles B. Sturde-
want and Professor John Faig are de-
welcoming some wonderful results. In
stead of using the high potential cur
rent necessary in the Marconi system
they use an ordinary dynamo to make
the current that is transmitted through
space. For a receiver, they use an
ordinary Bell telephone receiver, thus
simplifying the process of telegraphing
| without wires.
Professor Sturdevant writes as fol-
lows concerning the subject of wire
| less telegraphy and of the experiments
| being made here.
Since electric space telegraphy, or
wireless biography, as it is usually
called, has been brought into such
prominence by the recent visit of
Signor Marconi to our country, it might
not be inappropriate at the present
time to call attention TO systems Of
/ space telegraphy other than that which
| bears MarcOnis name.
| There are two other systems, the
general principles underlying which
are fairly old and we'll understood. The
first and oldest of these, known as
the earth current or leakage system,
utilities the earth as a conductor Of
electricity. The current in passing
from one earth plate or electrode
through the earth to a distant electrode
spreads out over a broad area and
| causes an electric pressure between
two other Well-separated electrodes in
cluded anywhere in this area. Ordin-
airy telephone crOsS-talk may be attri-
buted to these phenomena.
| The second method, which has been
used for purpOsive space telegraphy,
depends upon the magnetic induction
or mutual induction between two in
sulated conductors stretched upon
poles in parallel lines, one being To-
Gated at the transmitting and the other
at the receiving station.
This system has been in actual regu-
lar use for some time at a point near
Cardiff, England, and has been devel-
oped largely by w. H. Preece of the
British Postoftice Department.
During recent experiments with the
Marconi system of space telegraphy
conducted by the mechanical and cleo
trical engineering department of the
State College of Kentucky, we were led
to experiment also with the magnetic
induction system in order to determine
, its comparative efficiency and practi
cability. This system, in it's present
stage of development, is probably mo-
capable of such general application az
the Hertzian telegraphy, yet it ha:
several cOmpensating advantages
which make it more desirable for shor
Il i.tn or 1rOIn or.
ic waves, the laws of which are sim,
pie and we'll understood. These wave!
are of very low frequency as compared
; with the Hertz waves of the Maroon
system, and, consequently, are indie
pendent of all obstacles except from
and are only slightly weakened and de
Elected by conductors.
It's distinct advantage, however, lie
: : in the fact that the apparatus neces
sary for transmitting and receiving ar
D not too remote from standard type
of dynamos and motors Any genera
tor that will produce a pulsating cur
, rent, together with a suitable key o
switch, which will make ordinar
Morse signals, and pole line grounde
4 at each end, constitutes all the appa
I ratus required at the transmitting sta
e ton. At the receiving station an or
= binary Bell telephone receiver, place
0 in corresponding pole line is all tina
D is necessary to receive signals owe
: short distances.
o AS a further advantage this syster
: is to a certain extent selective as com
v pared to the Marconi system, for it wi
: transmit messages in only two direC
= lions, perpendicular to the inductiv
IL plane. To my knowledge message
e have never been sent further than thil
: teen miles by this method, yet there
e little doubt in the minds Of those VIII
q have worked upon this system tia
e with more delicate receiving apparatU
a, than has yet been constructed the di!
'e lance can be increased very greatly.