Vermont phÅ“nix. [volume] (Brattleboro, Vt.) 1834-1955, 1895-06-14
THE TELEPHONE TROUBLES
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When the telephone was first used Oh
telegraph circuit. it was noticed that hiss
ing and frying sounds could be heard as
well as Geographic signals of all sorts, all
of which had their origin in other electric
circuits. Sometimes these extraneous
noises were so much stronger than the tel
ephonic speech that they quite overpower-
ed it. The din destroyed the articulation.
This was the case when the automatic
Wheatstone transmitter was employed on
a telegraph circuit parallel to a telephone
circuit on the same poles. This was at
first Interpreted as being due wholly to in
ductlOn, and for business purposes tele
phone lines were removed as Tar as pract
cable from telegraph lines. The trouble
did not cease. In some cases 1t was nearly
as bad as before, and then 1T was apparent
/ that the source of the disturbance was the
/ earth itself. Both circuits made use of il
/ as a part of their systems. and their ground
! connections were adjacent, Ottentimes
! practically the same. When the telephone
] ground, as 1t was technically called, was
moved away. there was some relief, but it
/ was found possible to detect telegraph sig
| nails from lines separated by miles OF earth.
/ When compared with Geographic instru-
ments, the telephone is found to be eN-
! ceedlngly sensitive. A sounder requires
/ about the tenth OF an ampere to work it
/ properly, a relay, about the hundredth of
/ an ampere but a telephone will render
! speech audible with less than the nil
| lonth OF an ampere. and is. therefore.
more than ten thousand times more sensi-
tive than a Geographic relay. When the
! earth is made TO form a part of an electric
J circuit, the current does not 60 in mar
row strip from one ground terminal to
the other, but spreads out III a wide sheet
! much broader than perhaps most have i'm
/ aglned. Thus. Il the grounds be no more
than three or four miles apart, the spread
/ ing earth current can be traced III a sheet
/ as much as two miles wide II the
! grounds be still further apart, the sheet
will be correspondence wider This earth
] current in its course may meet with streams
/ of water. gas and water-plpes and other
| conductors better than the earth itself and
! these will conduct some OF ii. but moi all.
! The stronger the current the more it is
spread, and a telephone ground connection
I anywhere IN its path will receive its share
! unavoidably.
In cities and towns employing the troll
ley railway system, the rails form part of
the circuit. As they lie upon the earth. the
earth necessarily conducts away a notable
I
rails and good the connection. For in
stance, i'll Boston. where great pains has
been taken to provide ample metallic con
ductors III rails and return wires. thous-
and amperes have been found TO return
through the earth TO the power-house. and
this Is something like ten per cent of the
whole output How widely such a current
may spread may be imagined. and one may
compare such a current with the minute
one needed tOI telephone work. one
must remember that steady current does
not affect the telephone all IL is only
when the current varies IL strength above
a certain rate, 80 or 40 times a second.
that ii begins TO be troublesome The va
rlatlons III strength come from the Morse
KEY or It's substitutes in teegraphy. from
some types OF arc lighting dynamos. from
alternating dynamOs Tor incandescen.
lighting. and from the mo Ors in railway
work. Though there be a thousand am
peres III the earth. if the variation be bu,
one ampere. the 500 which which are con
slant are not offensive. hence il does no,
so much matter now much current is in
the earth as how rapidly il varies. There
are other currents in the earth due 10 nat
ural causes, such as lightning, auroras, etc,
which have sometimes been destructive u
the telephone and It's connections. IC
protect both service and the telephone H.
sell there is one remedy. namely, TO ceast
using the ground as a part OF the needfu
circuit, and 10 provide each lnstrumen,
with q complete wire circuit Telephone
companies are adopting this method every
where as fast as practicable. Ii Is more
costly 10 establish and maintain. but IL has
been made necessary by the nature OF cleo.
trlCal action and by tine great iucrpaE ST. IL
industrial enterprises within the past ter
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