The Minneapolis journal. [volume] (Minneapolis, Minn.) 1888-1939, 1905-12-26
HUMAN VOICES TO
SPAN CONTINENT.
Pupin Device Gives the Wires a
Carrying Capacity Of 5000
Miles.

Pittsburg, Pa, Dec. 26.-There has
Just been completed in this vicinity by
the Bell Telephone company a trunk
cable to be used eventually as a con-
Meeting link between New York and
San Francisco. This new line reaches
from MeKeesport to sewiekley, and is
tend the range of telephone transmits
sion, insuring not only the covering OF
distances up to thousands of miles by
the human voice, but also clearness.
The device is the invention of Profess
sor Pupin of Columbia university, and
by it the telephone officials believe they
problem of a coast-to-coast telephone
system.
Beginning with the new year, con-
struction work will be begun on similar
sections Of the same cable and equipped
with the same device, this SECTION be-
Brushton, Swissvale and Grafton with
the Grant exchange down town. One
of these sections will ultimately form
part of the transcontinental trunk lines
when it is completely established. The
Grafton line will reach the city by way
of the South Side hill districts, thus
giving those sections of. the city the
benefit Of the improvement.
Spans Entire Continent.
Professor Pupin 8 discovery came at
ter years of study and experimenting
From mathematical formule the cleo
trical principles necessary to increase
the range Of telephone talk were de-
duced. By the old method, using I'M
limit of conversation. This now has
been increased to 5000 miles by the use
of the Pupin device. By aerial cable
| the ordinary wire was only satlsfac-
tory at distance Of 1900 miles. The
| breadth of the continent now can be
easily .spanned by the use of the new
| method.
When experiments were first made in
| order to ascertain if wire communica-
| ton could be established between New
| York and the Pacific coast, it was found
| that the cable would have to be two
| inches in diameter. Such a line would
weigh 1920 pounds per 1000 feet: This
practically impossible, not only on &C
count Of the enormous weight Of the
| trunk lines and the frequency of the
| poles, but because of the cost. Copper
| ranges about Is cents pound now.
Employees Being Instructed.
BY using the Pupin loading coil de-
sides of the continent can be placed in
communication with each. other thru a
wire that is only three-fourths Of an
inch in diameter. This means that such
a telephone link would weigh only 1922
pounds per 1000 feet-just one-four-
teenth Of the weight Of the other; The
wire for the Pupin DEVICE would be
about the same size as that used by
trolley car companies for the trans
mission of power along the street. This
| means that the supports on such a trans
continental line as proposed would have
to be at a lesser distance that at pres
emit employed. 49,
The telephone systems Of the country
are now spread from ocean to ocean
with one short disconnecting link be-
| tween points in Nebraska and Colorado;
but with the wires in use it is impos
sible to utilize this system. The gaI
is now being bridgea with a trunk line
part of the ocean to-ocean telephone
i When this is accomplished, it will only
be necessary to take down the wires
between New York and San FRANCISCO
and substitute the three-eighth-incl
wires needed for the Pupin system.