Evening star., 1896-09-12

the gaps. The difficulty Is overcome by
operating two keys on the sounder instead
of one, as In ordinary telegraphy. One key
Is attached to the positive pole Of the bat
terry: the other key Is attached to the neg
ative pole. Thus by depressing either key
an impulse is created in different directions
over the line. AS short cut to brevity
1t may be said that the polarity of the cur
rent changes constantly and the current
travels In either direction. backward or
forward, at the will of the operator. This
Is reduced to practical basis in an in
genious manner
On the receivers desk in the "a hIe sta-
ton will be found large double magnet.
suspended between the poles of this mag
net Is small elongated coil Of WIRE The
coll hangs suspended in the air by means
OF a delicate hbrous thread. The current
from the cable is made to pass around the
coll. which, as 1t Is hanging between the
poles OF the magnet. will turn backward
or Forward In response to the particular
end of the line: for 1T IS the popularity Of
an electrified coil of wire to so act when
suspended between magnetic poles.
Producing the Waving Line.
Connected to one end Of the coil of wire
Is another thread Of fibrous material This
thread runs to fine glass tube which is
not larger than one-hundredth of an inch
In diameter. Ink flows through this small
tube. AS the tube is movable it is obvious
that the action of the coil Of wire moving
backward ana forward will also cause the
INK tube to move backward and forward
AT least the coil pulls the tube In one d.
rect1on and small spring returns 1t to
It's place The end of the tube rests lightly
on long strip of paper. which is kept
moving along constantly by an ordinary
cfockWork mechanism. Thus it will be
seen that the depression Of the transmitting
Keys results In waving line on paper at
the other end of the cable system.
"a or GfrNh.N t-
great iifi1culty is experienced in inducing
the ink to flow from 1t. The desired object
Is finally gained by means Of electricity. A
static current Is sent through the ink in
strip of paper to the negative pole of the
battery beneath. Static electricity. as 1t
has great electromotive force will easily
pass through paper. therefore there is a
continual succession of sparks flowing
through and carrying the small column Of
INK along with 1t as far as the surface of
the paper where it Is deposited In a waving
line This Is the line which Edison cannot
oes,iD, osan nut @ which Is as plain as day to the
ordinary cable operators. The latter sit
and watch this tape all day long 1t tray-
els slowly In front of them a distance of
three feet or more before 1t runs Off the
end OF the table into a basket. The words
are generally unintelligible to the operator
for 1t is seldom that other than cipher dis
patches are sent over the wire
When no current or message is passing,
the sensitive coil of wire attached to the
siphon remains at rest and a straight line
ts traced down the center Of the paper; for
of course, the tape keeps moving along
constantly. message or not. This line Is
known as the zero line and all variations
from 1t determine what the man at the
other end OF the line is saying Sometimes,
however, earth currents leak through to
the core of the cable and send the siphon
careening backward and forward in an
alarming manner. Then II message comes
through at the same time the wild actions
of the siphon become unntelligibIe indeed
In such case the operator is compelled to
study the form of the fine made by the
earth current and then to note the differ
ence between 1t and the true message. In
short, he makes his earth current line his
zero mark and determines his message ac-
Ccrdingly.
1t is in this connection that we must look
for the true reason why We are unable to