Evening star. [volume] (Washington, D.C.) 1854-1972, 1927-01-23
Long Distance Voice Communication Has Shown Marve

ington. Baltimore, Chicago and every
other city in the country its opportun-
itve to speak with any English teie-
phone user.
Naturally, Great Britain, with far
flung domains. Is enthusiastic over
the prospect. r. G.. Kellaway, former
British postmaster general and pres
ent managing director of the Marconi
Co., in a formal statement. declared:
The possibilities OF international
telephony are simply fascinating. For
instance. the Duke of York will open
the new houses of Parliament in Aus
trala this wear. If wireless telephony
were established and the hour in each
country conveniently arranged, see
no technical difiiculty in sending the
dukes speech to London and having
it broadcast throughout Britain"
Mr.. Kellaway further stated that at
comparatively trivial cost England
could this year commence wireless
telephony with Canada, Australia,
South Africa and India.
THAT we can now soherly think in
- such terms is due largely to the
ingenuity Of those long distance pio-
neers who, hack in the closing years
of the last century. labored on the
problem of getting enough energy into
a wire 20 carry the voice several
miles. For when words are spoken
into telephone instrument the voice
energy OF the speaker gradually di-
minishes as II flows along the line. In
much the same way as the sound of
the voice in an open space decreases
as the distance from the speaker
increases.
T,t,is dffHenlAxw yu,s overeoroe nv the
invention q the telephone repeater,
device whose function is analogous to
that of a third party standing between
two persons in a field for the purpose
of relaying the messag es Of one to
the other because their voices are not
sufficiently strong to carry" the full
distance. In telephone circuit, when
the voice energy Of the speaker has
decreased to very small volume, the
repeater injects new power into the
line, and this process continues, per-
haps several times. until the sound
reaches the listener with sufficient vol
ume to be heard distinctly. Without
such Instruments commercial. CONVEX
sations could not be carried on sue
cessfullv for distances of more than
about so miles.
With the type Of equipment now in
use the voice energy is ampified about
2OU times at each repeater station, but
the amount of energy handled is very
small.
Resorting to statistics. the engineers
tell us that IL conversations were car.
ried on continuously for a period of 10
years, the accumulated voice energy
which is received in one of these re-
peaters would only be sufficient to
light an ordinary 5o.watt lamp for ap-
proximately one minute. This is be-
cause the power Of the normal human
voice is twenty-five millionths of
watt.
The first telephone repeater to be
used commercially was installed in
1904 on a circuit between Amesbury
and Boston, Mass This was known
as the mechanical type of repeater.
and similar In construction to the
present telephone transmitter. 1t was
used more or less successfully for a
number of years. But after certain
developments it was replaced by the
vacuum tube repeater, which is the
type now used.
These are very much like the famil.
lar amplifiers used in radio receiving
sets. The first important use Of this
type of repeater was on the trans.
continental circuit between New York
and San Francisco, which was estab-