Perrysburg journal. (Perrysburg, Wood Co., O. [Ohio]) 186?-1965, 1914-07-02
TO TALK OVER SEA BY PHONE
Only question of Time Before
0cience Will Overcome Pres
ent Difficulties.

ent Difficulties.
London-In lecture just delivered
at the Royal Institution, DR.. j. A.
Fleming, f. r. s., described the in
ventions which of late years have
rendered possible great increase in
the distance of telephone communi-
cation and have permitted the use of
submarine telephone cables over dis,
tances previously impracticable.
The lecturer explained that in the
case of telephone wire the shorter
the wave length the greater the veloc-
ity with which the waves travel,
while the amplitude of the shorter
waves attenuates to a greater extent
than that of the longer ones
Hence, when, as a result, of speak
ing to telephone transmitter, a COM
pleX electromotive force is applied to
the end of cable the various simple
harmonic waves into which the inn
pulse may be resolved travel along
the cable with unequal speed and at
tenuation. The short waves travel
fastest, but are worn out soonest;
hence the wave form is distorted.
A remedy for the distortion of ar
ticulate sounds was first suggested
by Mr. oliver Heavyside, who showed
mathematically twenty-five years ago
how waves of all lengths could be
made to travel at the same speed and
attenuate at the same rate.
An important advance was made by
Prof. Pupin of Columbia College, New
York, in 1899 and 1900, when he
proved that Heavyside's suggestion
can be put INTO practical form by
loading the cable with coils of wire
wound on ironwire cores, inserted at
equal intervals, but so close that at
least eight or nine coils are included
in the distance of one wave length of
the average wave frequency, which is
always taken at 500. g,
If the coils are placed farther apart
relatively to the wave length they do
more harm than good. Aerial lines,
underground cables, and submarine
cables, can all be treated in this way.
The longest aerial loaded line is
that from New York to Denver, 1000
miles, which permits good speech be-
tween those places, and it is the am
bition of the American Telephone and
Telegraph Company to complete a
loaded line that will render speech
possible between New York and San
Francisco, over 5000 miles.
A line has just been completed be-
tween Berlin and Rome. 1t runs over
head, except through the Simplon tun-
mel with loading coils at every eight
miles, and good speech is possible
over the whole distance.
In this country the longest loaded
lines are two trunk lines from Lon
don to Leeds, 200 miles. The general
Pest Office has now in operation 30,-
900 miles af aerial and underground
loaded circuits, and 45,545 miles are
in the course of being loaded.
AS regards loaded submarine
cables the general Post Office has
three-one to France, twenty-one
nautical miles long, one to Belgium,
.forty-eight niles. and one to Ireland,
.sixty-four miles A fourth, which is
now being manufactured, is to be laid
from Suffolk to the nearest point in
Holland, 125 miles. Broadly, loading
has rendered it possible to double or
more than double the distance of ef-
fective telephone intercourse.
In regard to wireless telephony, DR..
Fleming said the arrangements are
closely similar to those employed in
wireless telegraphy, but in the base
of the antenna, or coupled to it. must
be placed a microphone, by means of
which the speakers voice makes
changes in the resistance of the an
tenna circuit, the result being to vary
the amplitude of the waves emitted
without altering their wave length.
The difficulty is to obtain a micro
phone that will carry large high fire.
quency currents. By the aid of an in
genious liquid microphone Prof.
Vanni of Rome has transmitted
speech for 625 miles. Fessenden in
the United States has telephoned a
few hundred miles, and Poulsen in
Denmark, Colin and Jeance in France,
Goldschmidt in Germany and Dit
cham in England have covered greater
or less distances.
The lecturer concluded by remark
ing that we are yet long way from
telephony across the Atlantic, wheth-
er with cables or by wireless, but pro-
gress will continue to be made, and
it is possible that some day speech
transmission from England to San
Francisco, with one repetition at New
York, may be an accomplished fact.