<h2><SPAN name="CHAPTER_XIX" id="CHAPTER_XIX"></SPAN>CHAPTER XIX.</h2>
<h3>THE TELAUTOGRAPH.</h3>
<p>So far we have described several methods of
electrical communication at a distance, including
the reading of letters and symbols at
sight (as by the dial-telegraph and the Morse
code embossed on a strip of paper); printed
messages and messages received by means of
arbitrary sounds, and culminating in the most
wonderful of all, the electrical transmission of
articulate speech.</p>
<p>None of these systems, however, are able to
transmit a message that completely identifies
the sender without confirmation in the form of
an autograph letter by mail.</p>
<p>In 1893 there was exhibited in the electrical
building at the World's Fair an instrument
invented by the writer called the Telautograph.
As the word implies, it is a system by
which a man's own handwriting may be transmitted
to a distance through a wire and reproduced
in facsimile at the receiving-end.
This instrument has been so often described in
the public prints that we will not attempt to
do it here, for the reason that it would be im<span class="pagenum"><SPAN name="Page_166" id="Page_166"></SPAN></span>possible
without elaborate drawings and specifications.
It is unnecessary to state that it
differs in a fundamental way from other facsimile
systems of telegraphy. Suffice it to say
that as one writes his message in one city
another pen in another city follows the transmitting-pen
with perfect synchronism; it is
as though a man were writing with a pen with
two points widely separated, both moving at
the same time and both making exactly the
same motions. By this system a man may
transact business with the same accuracy as
by the United States mail, and with the same
celerity as by the electric telegraph.</p>
<p>A broker may buy or sell with his own signature
attached to the order, and do it as
quickly as he could by any other method
of telegraphing, and with absolute accuracy,
secrecy and perfect identification.</p>
<p>In 1893, when this apparatus was first publicly
exhibited, it operated by means of four
wires between stations, and while the work it
did was faultless, the use of four wires made
it too expensive and too cumbersome for commercial
purposes; so during all the years since
then the endeavor has been to reduce the number
of wires to two, when it would stand on
an equality with the telephone in this respect.
It is only lately that this improvement has
been satisfactorily accomplished, and, for reasons
above stated, no serious attempt has been<span class="pagenum"><SPAN name="Page_167" id="Page_167"></SPAN></span>
made to introduce it as yet; but it has been
used for a long enough time to demonstrate its
practicability and commercial value. Companies
have been organized both in Europe and
America for the purpose of putting the telautograph
into commercial use.</p>
<p>By means of a switch located in each subscriber's
office the wires may be switched from
a telephone to a telautograph, or vice versa,
in a moment of time. By this arrangement a
man may do all the preliminary work of a
business transaction through the telephone,
and when he is ready to put it into black and
white switch in the telautograph and write it
down. For ordinary exchange work this is undoubtedly
the true way to use the telautograph,
because one system of wires and one
central-station system will answer for both
modes of communication, and in this way an
enormous saving can be made to the public.
There is no question in the mind of any one
who is familiar with the operation of both the
telephone and telautograph but that some day
they will both be used, either in the same or
separate systems, as they each have distinctly
separate fields of usefulness,—the telephone
for desultory conversation, the telautograph
for accurate business transactions. The question
may arise in the minds of experts how the
two systems can be worked in the same set of<span class="pagenum"><SPAN name="Page_168" id="Page_168"></SPAN></span>
cables, and this leads us to discuss the phenomena
of induction.</p>
<p>Every one who has listened at a telephone
has heard a jumble of noises more or less pronounced,
which is the effect of the working of
other wires in proximity to those of the telephone.
If, when a Morse telegraph instrument
is in operation on one of a number of wires
strung on the same poles, we should insert a
telephone in any one of the wires that were
strung on the same poles or on another set of
poles even across the street, we could hear the
working of this Morse wire in the telephone,
more or less pronounced, according to the distance
the wire is from the Morse circuit. This
phenomenon is the result of induction, caused
by magnetic ether-waves that are set up whenever
a circuit is broken and closed, as explained
in Chapter VI.</p>
<p>The telephone is perhaps the most sensitive
of all instruments, and will detect electrical
disturbances that are too feeble to be felt on
almost any other instrument, hence the telephone
is preyed upon by every other system of
electrical transmission, and for this reason has
to adopt means of self-protection. It has been
found that the surest way to prevent interference
in the telephone from neighboring wires
is to use what is called a metallic circuit—that
is to say, instead of running a single wire from
point to point and grounding at each end, as<span class="pagenum"><SPAN name="Page_169" id="Page_169"></SPAN></span>
in ordinary telegraph systems, the telephone
circuit is completed by using a second wire instead
of the earth.</p>
<p>As a complete defense against the effects of
induced currents the wires should be exactly
alike as to cross-section (or size) and resistance.
They should be insulated and laid together
with a slight twist. This latter is to
cause the two wires so twisted to average always
the same distance from any contiguous
wire.</p>
<p>One factor in determining the intensity of
an induced current is the distance the wire in
which it flows is from the source of induction.
A telephone put in circuit at the end of the
two wires that are thus laid together will be
practically free from the effects of induced
currents that are set up by the working of
contiguous wires—for this reason: Whenever
a current is induced in one of the slack-twisted
wires it is induced in both alike; the
two impulses being of the same polarity meet
in the telephone, where they kill each other.
In order to have a perfect result we must have
perfect conditions, which are never attained
absolutely, but nearly enough for all practical
purposes.</p>
<p>In the early days of telephony great difficulty
was experienced in using a single wire
grounded at each end in the ordinary way, if
it ran near other wires that were in active use.<span class="pagenum"><SPAN name="Page_170" id="Page_170"></SPAN></span>
As time passed on and the electric light and
electric railroad came into operation these difficulties
were immensely increased, till now in
large cities the telephone companies are fast
being driven to the double-wire system, which
will soon become universal for telephonic purposes
the world over, except perhaps in a few
country places where there is freedom from
other systems of electrical transmission. To
successfully work the telephone and telautograph
through the same cables, these protective
devices against induction must be very carefully
provided and maintained.</p>
<hr style="width: 65%;" />
<p><span class="pagenum"><SPAN name="Page_171" id="Page_171"></SPAN></span></p>
<div style="break-after:column;"></div><br />