The Scranton tribune. [volume] (Scranton, Pa.) 1891-1910, 1897-06-04


and with a frequency of change that |
can be adjusted to the requirements of |
the work which the current is called |
upon to perform. Now 1t is familiar |
fact that IL constant current which |
possesses any particular force is inter- |
rupted by the separation of two wire
terminals that have been in contact
a spark will be emitted. But II an
alternating current be interrupted, and
IL the interruption occurs at just the
stage of an alienation which is mid
way between a positive and a negative
wave, there will be no spark, because
the force which was flowing in one
direction subsidies to zero before 1t be-
gins to flow in the other. What Messrs.
Squier and Crehore propose, then, is to
Interrupt their current and restore 1t
at just such zero points" in the oscil-
liation as this. But the sparks will not
disappear unless the make" and
break" occur at precisely the right in
stant; and thus a single and valuable
guide Is afforded the operator in
ADJUSTING HIS APPARATUS,
When he finds that sparkling has
ceased he knows that his transmitter
interrupts and restores the flow at the
zero stage, and is working in perfect
harmony with the particular frequency
of alteration employed. The perform
ance of the instrument would then be
"synchronous" with that of the dy-
namo or generator. Hence such tel
egraph may properly be called syn
chronograph." In fact, that is the
name adopted by Messrs. Squier and
Crehore.
Now, let us suppose that the Morse
alphabet, which is composed of dots
and dashes, is to be tried with this sys-
TEN. In that case a break lasting
from the beginning of apositive wave
until it's end might stand for the dot,
and the break from the beginning Of a
positive wave, but continuing past its
subsistence through the rise and fall
of the negative wave also, would make
a dash. OF course. it does not matter
whether the interruption occurs at the
beginning of a positive or of a mega
tive wave. The only essentials are
that 1t shall begin at a zero stage and
shall last just half a "cycle" or whole
"cycle." 1t takes positive and neg
ative wave together to make cycle.
From these statements one will readily
infer that the length of the spaces
BETWEEN DOTS AND DASHES
or combinations thereof must also be
either half a cycle or some multiple
| thereof. In most of the experiments
| described in Lieutenant Squier's story
| the continental code was used. In this
| two dots are used in place of the dash
of the Morse alphabet. But the prin-
ciples involved are identical
..t.
| sent with an alternating current is
very simple. A narrow wheel with a
| fiat, narrow periphery is kept in ro-
| tation at a rate which is rapid and is
| equal to an integer number of cycles.
| That is to say, when the time required
| for a revolution is divided by the length
| of one cycle, there must be no frac-
| ton remaining. The quotient must be
a whole number, like 40. This relation
| between the two can be maintained
| accurately by driving the wheel with
| gearing, either from the dynamo which
| operates the current or, what is more
| practicable, an alternating current
| motor operated by the very electricity
| used in telegraphing. Let us imagine.
now, that the wire carrying the mes
sage is cut in two, and the adjacent
| SHuS are plONlueu WITH
FLEXIBLE METALLIC TIPS.
or brushes" and that these two
brushes rest side by side on the peri
| phery of the wheel. Obviously, the
| current will flow from one brush into
| the metal of the wheel, and thence
into the other brush. so, long as the
wheel remains clean. If, however, a
| little patch of paper or other insulat-
| ing material be attached to the peri
phery at certain point, every time it
comes round it will break the contact
between the brush and the wheel, and
thus open the circuit. AS soon as the
patch is past the connection will be re-
| stored.
This, however, was not the exact plan
really pursued. In practice, a long,
narrow strip of paper was kept in mo-
tion by the wheel, just as a belt Is by
a pulley. This strip had been previous
ly perforated with holes of different
lengths, long or short, and carefully
| spaced. One brush rested on top of 1t
and the other pressed upward against
it from below, the two being removed
short distance from the wheel and
situated one directly above the other.
! So long as the brushes were separated
by the paper strip no current would
flow, but when a hole permitted one
to reach through and touch the other
| the current
| WOULD BE RESTORED.
The Interruptions and restorations of
the current always occurred at the zero
| stage. between DOSitiVe and mega five
waves, so that no sparkling resulted
after the brushes were once adjusted
For convenience, in one experiment, the
ends of short strip were fastened to-
gether precisely like betting, and the
| same message was sent over and over
again. An actual speed of 1900 words
a minute was secured in this way, and
three or four times that rate is said
to be entirely feasible.
| The precise form of the receiver used
on this occasion need not be fully de-
scribed, because it is not especially
preferable to several other weil-knowr
| fornnS OF automatic receivers. 1t Is
sufficient for present purposes to say
that the current was led through a col
of wire around an optical instrument
known as an "analyzer." A beam OF
polarized light had been sent from an
arc lamp through series of apparat-
us of which the analyzer formed part
and this particular object had been ro-
tated far enough to eXtinguish the ray
when no current was flowing. In ac-
cordance with a well-known law, the
passage of an electric current rotated
the plane of polarization" in such a