Burlington weekly free press. [volume] (Burlington, Vt.) 1866-1928, 1909-02-18
ELECTRICAL SCIENCE.
Development OF the Wireless 'ieic-
phone and Its Wonderful Fossil
biIttieS.

biIities.
j. Erskine- Murray. D. Sc. writing for
the London Times SAYS that it is a con-
mon notion among the writer's II scicr-
tihc papers that the publication OF tho
results OF a lahorious research in the
pages Of the proceedings" OF some learn
ed society Ia publication to the world
at large. Unfcrtunately. perhaps. 1t is
not SO. and tho public in general
remains in ignorance. probably for dc
cade or so II the research has been a
really important one; otherwise for long
er. The announcement last week thai
the United states government had placed
AZ order for twenty-eight sets Of wire
less telephone apparatus would appoar
to be something quite new, hut II 's
merely a step forward to those who have
followed tho development Of wireless tel
ephony from the days Of Graham Bells
photophone nearly thirty years ago 10
the production OF the modern electrical
open circuit telephone. It is. however,
from all points OF view an important
step: 1t places the invention on differ
ent plane by bringing 1t into an arena
where its value VIII te determined by
many things besides INGENUITY and OK
have to compete with established meth
DDS and overcome the inertia. perhaps
the active opposition Of vested interests.
The electric wireless telephone has hc-
come possible through the development
Of methods for the production Of con-
tinuous series of simple or complex cleo
trical discharges following one another
al the rate Of 5Ooo0 OF moro per second.
rr-t ,.r a't r.-n
ton is advantageous FOR two reasons
would produce an audible note,
ard also would not he cap
able of rendering electricalv tho
higher harmonics which give the sounds
OF speech their distinctive characters
secondly, because II is only by using n
high frequency that II is possible 70
transmit a large amount Of energy while
using comparatively small quantity Of
electricity.
There ara several methods OF produc-
ing suitable series Of discharges. II Is
not necessary that these should form
true alternating current and so long
ms the frequency l. Sufficiently high any
type Of dischnrtc FROM n rapid success
sion % oscillnt,rC sparks to the uniform
" alternating current Of an ordinary al
tcrnato current generator may be en-
nloyed These remarks apply equally to
wireless telecraphY. though the latter is
not limited by the condition that the
spark rate must be high enough to be
inaudible The difference between tel
egraphy and telephony Hes mainly in rhe
manner III which tho electric current Is
controlled. In the former the variations
caused by pressing the Morse key are
simple and definite. in the latter the mo-
ton Of the mcrophone diaphragm caused
by speech Is almost infinitely complex,
and the strength. or frequency, OF the
transmitting current must be made to
vary in strict accordance. In the wire
telephone the concentration OF the cur
rent along one linear conductor from the
speaker to the hearer makes II possible
TO work with low vcltaGes ard with an
electric current which is. in all US vari-
ntions. an exact replica of the sound
waves Quire large percentage Of the
electrical energy sent out along tho wire
arrives at the receiver. This is not tho
case in wireless working whore tho
transmission Is over plane and not
confined to n line, and whore. thereto
only very small fraction Of the en-
ergy sent out BY the transmitter is pick
cd ND by the receiving station. II has
thus been found necessary TO use cur
rent whose true frequency has no direct
relation to that OF the sound waves
transmitted by II. Thus the sound Of a
mans voice, giving, say. 700 vibrations
per second. Is Transmitted by an electric
current making 10000 vibrations in the
same time. The ways in which this may
be done are simple enough in theory.
For instance, the strength or the ampli-
tudc Of tn" current may be made 10
vary In accordance with the sound
waves. The result Is a current whose
frequency remains 100 nh0 but which va
ries In strength from maximum to a