The Republican. [volume] (Oakland, Md.) 1877-current, 1880-03-20

department, usually in the base
ment. where the messengers are con-
Here it is copied in letter
press placed in an envelope and sent
by the Uniformed Brigade" for de-
livery.
The method of transmitting intelli-
gence by electricity may be briefly
stated as follows:
The wire is electrically charged by
being connected at both ends with q
galvanic battery. When this connec-
ton is broken, chemical action in the
battery ceases, and the wire is again in
its natural condition. The instruments
used are OF three kinds, viz: single line
Instruments, which permit the sending
OF only one message at time; the du-
pick, by which two messages Zone each
Way) can be sent at the same time; and
the quadruplex, by which arrangement
-FOUR messages can be sent and received
at the same time-two each way. The
single line instrument is very simple in
Its construction. 1t consists of soft
iron cones in the shape of a horseshoe
magnet wound with fine wire. This
line wire is connected with the line
wire, and is a part of the circuit
Therefore, when the circuit is complete
the current passes through the fine
wire around the soft iron cones and
magnetizes them. Included in the cir
cult is what is technically called key
for the purpose of opening and closing
the circuit, or, in other words, making
and breaking the contact. The cones
lose their magnetism the instant the
circuit is broken. An armature, also
OF soft iron, is suspended near the ex
posed ends of the cones to which 8
spring is attached to pull it away from
the cone when not under the influence
of the magnetic effect. Thus the arma.
ture is caused to vibrate correspond.
ingly as the key is worked to open OF
close the circuit. The effect on sim,
liar instrument at the distant end is
precisely the same; also, all inferno.
date instruments in the circuit. In
this manner the dots and dashes are
transmitted from any part of the line
to all other instruments.
The cable system of telegraphino
differs, necessarily, very much from
that of the land wires. 1t will be re.
membered that the first cable, laid in
1859, was complete failure, owing to
a lack of experience. Battery power,
supposed to be sufficient, was employed
without satisfactory results. More
battery was added without success, un.
til it was discovered that the battery
was so powerful that the conducting
wire in the cable was burned up, and
the consequence was complete failure
"a result as costly in pecuniary sense
as it was notifying and discouraging
to the protector. Repeated experiment;
at length demonstrated that less battery
and more sensitive instruments mus
be employed. The rejecting galvanom
eter is the only instrument at present
with which long cables can be success
fully worked with battery of low ten
sion. 1t consists of a needle formed O.
piece of watch spring, three eighths
of an inch in length, the needle sUs
pended by thread of cocoon silk with
out tension. The needle lies in the cen
ter of an exceedingly delicate gal
vanometer coil. A circular mirror O
silvered glass is attached to the needle
and reflects, at right angles to it, in tn,
plane of its motion. 1t is so curvet
that when the light of lamp is throw
through fine slit in it, the image O
the slit is reflected on scale, abou
three feet distant, placed little abov,
the front of the flame.
Dedections to the extent of half al
inch, along any part of the scale, ar,
sufficient for one signal. This instru
ment is necessarily used in darkene(
room. Condensers are used at boil
ends of the Atlantic cable. The tern
condenser has long been used among
electricians to denote an arrangement
equal to a Leyden jar of enormous ca
pacity. The condenser is charged from
small battery and discharged into thu
cable. The transmitting keys are con
veniently arranged to dischage from
these condensers into the cable cur
rent of either polarity, and the needle
at the distant end of the cable responds
but in opposite directions, as the cur
rents of different polarities are dis
charged through it. The reflection
thrown on the scale moves to the righ
and left, from which the reading il
taken. The eye can easily distinguish
at any point on the scale, to which the
spot of light may be detected, the be.
ginning and end of signal. .
The signals in this way follow each
other with wonderful rapidity. The
usual speed for messages is from twelve
to fifteen words per minute, but wher
the operators are conversing with eacf
other twenty 10 twenty-five words PEI
minute are usually attained. As to the
velocity of electricity, it takes abou
three seconds in cable across the At
lantic for the current to reach its full
strength. The current does not arriv'
all at once, but grows gradually from
minimum to maximum. For the dat;
which forms the subject matter OF thi
article the writer is indebted to Mr.. 0
K. Newton, the electrician of the West
ern Union Company. 1t is an astonish
ing fact that so keen are the percep
tions of some telegraphers that the.
can detect the sending" of men the.
have worked with even after lapse o
years, with the same facility that a.
expert tells the authorship of handwrit
ing by the formation of certain letters
-CincianGti Commercial.
Why We Butter Our Bread.
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