The new Northwest. [volume] (Portland, Or.) 1871-1887, 1872-02-16
How the Atlantic Telegraph is Worked.

How the Atlantic Telegraph is Worked.
We find the following interesting ae-
count of the working of the Atlantic
cable in a recent lecture by Hon. VII
liam ]. AIeAlpine, on the subject OF
''Modern Engineering"
TELEGRAPHY.
Telegraphy may, with propriety, be
considered one of the branches OF en-
gineering, and is peculiarly OF modern
development. a clever writer says that
il may be read by each of the five senses.
On land lines each signal Is made by
suspending the flow of the electric cur
rent, for two different intervals of time,
called "dots and dashes''-the use of
which, in different orders, constitutes
the alphabet of the telegraph. When
they are printed they are read by sight,
but ordinarily the operator reads them
by sound, as easily as the musician
reads the letters of the scale by the same
sense. If the operator has no instrument,
he viii grasp the wire in his hands, and
read the signals by feeling the inter-
missions of the flow of the electric cur
rent. In like manner, by placing the
wire across his tongue, he can taste
/ the same intermissiOn (but this is n
dangerous experiment. And il is said
/ that the electricity can be made to dis
solve chemical and produce pungent
odor in the telegraphic alphabet, which
can be read by smelling, but for this j
do not vOueh. / believe that the method
of signalling through the Atlantic cable
is known in detail to but few persons.
| The operation is exactly reversed from
J that flnn lnrsI 1fnne n1l,a t.f.rolts
covering of the copper wires, under the
pressure of a great depth of water, be-
comes an absorbent of the electricity
which is being sent through them to the
extent of 90 per cent. The first portion
of the electric wave of 10 per cent
crosses the ocean loo niles in two
seconds, and it would be followed by a
l succession of waves from the restoration
of that portion of the electricity which
has been ObsOrbed in the gutta percha in
impulses, and the signal would be re-
peated like echoes, and produce not only
confusion, but great delay. To remedy
this, Professor Narley introduced kew.
which sends alternate currents, positive
and negative, at such intervals as allow
the first wave of ten per cent. to pass
forward, and then that portion absorbed
by the covering l. neutrsdiZed by its op-
pOsite, and the cable is cleared for the
transmission OF a second pair of currents
, The battery used is very small on,
, three of Daniels cups, and the sigma
being only ten per cent. for this small
current, is pOwerless to move any of tn,
other instruments in use on land. TIL,
instrument used consists of Il minut
5 pOlariZed needle, suspended on singh
strand of a spiders web, or one from tn
silk worm. In the middle of this minut
needle is placed an almost MICROSCOPE
= mirror, which reflects a single ray @
4 light from a powerful lamp. The cur
rents of electricity affect this needle al
ternately to the right and left fora spae
of time corresponding to that Occupie,
in the signal on the land line, the sam
f kind of alphabet being used in boil
cases. The receiver mot OperatOr) sit
in a dark room, and the small miro
reflects the ray of light upon piece o
/ white paper before him, on which
| black line is drawn, to the right and lef
of which the light is alternately re
iiected. The receiver reads these signal
by sight, and transmits them to anothe
: person, placed outside the dark room, b,
means of an ordinary instrument. 4
short time since, General Reynolds tOlC
me that he had sent a message, withOu
either wire or cable, 81 miles, across ~
arm OF Lake superior, by means OF tn
HeliotrOpe or mirror, and on the returl
of his messenger who had been sen
with written copy he found that tn
, Heliotrope message had been received
!, understood and Obeyed. He had tw
= assistants, who had been telegraph
: operators, who had for whole summt
: been amusing themselves in talking |
each other with these instrument
I though they were stationed ten
= twenty miles apart. When the reb
= General Morgan made his great raj
= through Indiana and Ohio, he capture
- one Ofmy operators, and compelled him
: telegraph, in General Lew Wallace
!, name, to Cincinnati, asking how man
- regular troops Were in that city. Mo
= gan read by sound, and therefore ii
= operator did not dare to intimate tn:
|. he was under duress, and could onl
y venture to add an extra initial to II
: own signature. The receiving operate
: at Cincinnati knew that Morgan was !
= that neighbOrhoOd, and suspecting, froI
the extra initial letter, that all was M
. right, replied, greatly exaggerating til
), force of regulars; and the cOnsequenC
:, was that Morgan changed his route to
!, circuit of twenty miles beyond the cit,
= and thus saved it from a sack, and I'll
: probable loss of millions of dollars.