The daily phoenix. [volume] (Columbia, S.C.) 1865-1878, 1869-07-18
How tho Atlantic Gable is worked.

CouuI VI tue working OF the Atlantic
cable In q recent lecture by the Hon.
VIM. & McAlpine, on the subject of
Modern Engineering:" eaaJf & q
Telegraphy may, with propriety, be
considered one Of the branches of enei-
neering, and is peculiarly Of modern de-
velopment. A clever writer says that it
may be read by each of the Eve senses.
On land lines each signal is made by sus-
pending the flow Of the electric current
for two different intervals of time called
s'dots and dashes"-the use If which, in
different orders, constitutes the alphabet
of the telegraph. When these are print
ed they gre read by t'sight," but ordi-
narily the operator reads them by
'sound" as easily as musician reads the
letters of the scale by the same sense.
If the operator has no instrument, he
will grasp the wire in his hand and read
the Signals by feeling" the intermis-
sions Of the flow of the electric current.
In like manner, by placing the wire
across his tongue he can "taste" the
same intermission, hut this is danger
GUS experiment. And it is said that the
electricity can be made to dissolve a
chemical and produce pungent odor in
the telegraphic alphabet, which can be
read by smelling" but for this I do not
vouch. 1 believe that the method of
signaling through the Atlantic cable is
known in detail to but few persons The
operation is exactly reversed from that
of the land wires.
The gutta-percha covering of the cop
per wires, under the pressure of great
depth OF water, becomes an absorbent of
the electricity which is being set through
them to the extent of ninety per cent.
nhn Gr-ok 80
ten per cent. crosses the ocean q, 700
miles) in two seconds, and it would be
followed by succession of waves from
the restoration of that portion of the
electricity which has been absorbed by
the gptta-percha in impulses. and the
signal would be repeated like echos, and
produce, not only confusion, ,bnt great
delay. TO remedy this, Professor Var
ley introduced key, which sends alter
nate 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 is
neutralized by its opposite, and the cable
IS cleared for the transmission of Sc
cond pair of currents. The battery used
is very small one, three of Daniels
cups and the signal being ten per cent.
OF this small current, is powerless to
move any of the other instruments in
use on land. The instrument used con-
slsts of minute polarized needle, sus-
pended on a single strand of spiders
web, or one from the sik-worm. In the
middle of this minute needle is placed
an almost microscopic mirror, which re-
fleets single ray of light from a power
ful lamp.
The currents of electricity affect this
needle alternately to the right and left
for space of time corresponding to that
occupied in the signal of the land-lne,
the same kind of alphaber being used in
both cases. The receiver mot operator)
sits in dark room, and the small mirror
reflects the ray of light upon piece of
white paper before him, on which
black line is drawn, to the right and left
OF which the light is. alternately reflect
ed. The receiver reads these signals by
'tsight," and transmits them into an
other person, placed outside of the dark
room, by means of an ordinary instru-
ment. A short time since, Gen. Rey-
nolds told me that he had sent o mes
sage, without either wire or cable, nine
ty-two miles across an arm of Lake Su-
perior, by means of .the heliotrope or
mirror. and on the return of this mes
senger. who had been sent with a written
copy, he found that the heliotrope mes
sage had been received, understood and
obeyed.
He had two assistants, who had been
telegraphic operators, who had for
whole summer been amusing themselves
in talking to each other with these in
struments. though they were Stationed
ten, twenty or thirty miles apart. When
the rebel Gen. Morgan made his great
raid through Indiana and Ohio, he cap
tnred one of my operators, and compeil-
ed him to telegraph, in Gen. Lew Wal
lace's name, to Cincinnati, asking how
many regular troops were in that city
Morgan read by sound" and therefore
the operator did not dare to intimate
that he was under duress, and could only
venture to add an extra initial to his own
signatures. The receiving operator at
Cincinnati knew that Morgan was in |
that neighborhood. and suspecting,