IM- PROVEMENTS IN THE MODE OF AND APPARATUS FOR TRANSMITTING TELEGRAPHIC
Year: 1874

page_text: LETTERS PATENT to James- Wallace Brown, of Leadenhall Street, in
the City of London, Electrical Engineer, for the Invention of "IM-
PROVEMENTS IN THE MODE OF AND APPARATUS FOR TRANSMITTING TELEGRAPHIC
"
Sealed the 4th August 1874, and dated the 5th June 1874.
PROVISIONAL SPECIFICATION left by the said James Wallace Brown
at the Office of the Commissioners of Patents, with his Petition,
on the 5th June 1874.
I, JAMES WALLACE BROWN, of Leadenhall Street, in the City of
London, Electrical Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE MODE OF AND APPARATUS FOR TRANS-
MITTING TELEGRAPHIC SIGNALS," to be as follows:-
This Invention relates to the working of chemically printing and
recording telegraphs, the object being to increase the speed of trans-
mitting to receiving instruments telegraph signals through long circuits,
and more especially through submarine cables and underground wires.

page_text: I accomplish this object by a peculiar kind of perforated insulating
ribbon or strip of paper in combination with three transmitting pens
or contact points set abreast and insulated the one from the other.
These pens I connect two of them with opposite poles of the battery,
and a third I lead to earth, interposing in some cases a resistance coil.
The pen thus connected with earth I call for distinction the compensa-
tion pen. The perforations in the ribbon are so arranged that one only
of the pens shall be in contact at a time with the metal drum of the
transmitting instrument, and I provide for sending a reverse current to
line.
It may be remarked that the printed letters in this class of telegraphy
arc composed of dots or of dots and dashes, and that great difficulties
have been experienced in giving precision to the dashes, the tendency on
long circuits being to "tail" or to run the dashes into the dots and
thereby to render the printed message unintelligible.
I now propose when making a dash to send first a strong initial
current to line, and thereby to charge the wire to a high potential.
When the so called marking pen or contact point used for this purpose
breaks contact by reason of a solid portion of the ribbon coming under
the pen the compensation pen drops into contact a perforation of the
travelling ribbon being brought under it. This has the effect of clearing
the wire of static electricity (the said pen being connected to carth).
If however, no appreciable resistance were interposed between this pen
and earth the wire would discharge in so short a time that there would
only be a dot produced at the receiving end. But by introducing a
given resistance between this pen and carth the discharge of the wire will
be prolonged sufficiently to ensure the prolongation of the signal at the
receiving end up to a certain limit. To finish the signal or dash a second
strong current is now sent to line through the marking pen, and this is
instantly followed by a current to line in the opposite direction, caused
by the reversing pen dropping into a perforation of the ribbon.
It will be understood that the resistance introduced between the com-
pensating pen and earth must be adjusted to the static capacity of the
line.
It should be remarked that by my arrangement as I use the static
electricity to make one-third only of the dash, and then send another
current to line of same name as the first current, which I follow by a

page_text: reversed current of the same length and strength, I gain a most decided
advantage. In fact I use three distinct currents to make the dash, two
of same name, and one reversed. This result can either be accomplished
by the use of three pens insulated, the one from the other as described,
or by three drums insulated, the one from the other, and provided with
pens connected together, so as to make as it were one. Or by having
three rocking beams insulated from one another, and provided severally
with suitable contacts to make battery contacts, compensation contact,
and line by aid of certain springs, said springs having metal rods
passing through perforations of my particular arrangement after the
manner of the well-known automatic transmitter.
An advantage consequent on the use of my Invention is, that low
battery power as compared with that employed in single current systems
of chemically printing telegraphs can be used, as the full strength of
current is secured for every signal, whereas in single currents it is not.
Another advantage incidental to this Invention, is that it can be
arranged to put on dead earth between signals, thereby getting the full
strength of current to produce the signals. This is a great advantage
in working aerial lines with weak battery power, or purely intermittent
currents can be sent, also weak or strong reversals in centre of dash.
+
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Wallace Brown in the Great Seal Patent
Office on the 5th December 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
WALLACE BROWN, of Leadenhall Strect, in the City of London,
Electrical Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of June, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors
give and grant unto me, the said James Wallace Brown, Her special
licence that I, the said James Wallace Brown, my executors, admini-
strators, and assigns, or such others as I, the said James Wallace
Brown, my executors, administrators, and assigns, should at any time

page_text: agree with, and no others, from time to time and at all times thereafter.
during the term thereia expressed, should and lawfully might make.
use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention
for "IMPROVEMENTS. IN THE MODE OF AND APPARATUS FOR TRANSMITTING
TELEGRAPHIC SIGNALS," upon the condition (amongst others) that I, the.
said James Wallace Brown, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and
seals, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and cause
the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said James Wallace Brown, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement, reference being had to the Drawing here-
unto annexed, and to the letters and figures marked thereon (that is to
say) :—
This Invention relates to the working of chemically printing and
recording telegraphs, the object, being to increase the speed of trans-
mitting to receiving instruments telegraphic signals through long
circuits, and more especially through submarine cables and underground
wires. I accomplish this object by a peculiar kind of perforated ribbon
or strip of paper in combination with three transmitting pens, styles, or
_contact points (or their equivalents) set abreast of and insulated the one
from the other, as will be presently explained.
Before however I proceed to describe in detail the nature and operation
of my Invention it will be well to explain the present state of telegraphy
in its relation to chemically recording telegraphs, as the adaptation of
the Invention to existing systems will be thereby the better appreciated.
In working chemical telegraphs great difficulty is experienced in
producing legible telegraph signals through long aerial circuits, cables,
and underground wires for the reason that as the telegraph code is
composed of dots and dashes the wire is charged to a much higher
potential when making dashes than when making dots. This unequal
charging of the wire has the effect of running the dash into the dot that
immediately follows it, and when the cable or wire is very long this dash

page_text: is unduly prolonged, so much so that the whole letter which should be
composed of dots and dashes is little better than one long dash. If the
cable or wire were of short length comparatively speaking this would
not take place to any great extent, because the wire would discharge
itself in so short a time that there would be no appreciable drag upon
the signals. In long circuits however the wire will not discharge quick
enough, and hence the dragging out of the signals. Thus as the length
of the circuit increases so is the difficulty of obtaining intelligible signals
increased. By artificial means however this difficulty is remedied to a
great extent. The most common way of obtaining this result when
using single currents is to put a leak in line beyond the transmitting
instrument, that is, to connect the line wire to earth through a suitable
resistance beyond the transmitting instrument so as to allow the line
wire when battery contact is broken to discharge to earth through this
resistance. But this plan has the disadvantage that the battery, when
sending the printing current to line has to supply this leak or circuit
between line and carth also. But as the resistance between the line and
carth is reduced so is the strength of current in the line wire reduced.
Now if the line wire is of considerable length it will take so long to
discharge that it becomes necessary to make this leak between line and
carth of very low resistance in order to make the conditions of line right
to insure good signals at the distant end. If a very powerful battery of
low internal resistance be used the resistance between line and carth
'may be reduced in proportion. But this is limited because beyond a
certain limit it would be impossible to reduce this resistance between
line and earth for the reason that the strength of current in the lino
wire would not be great enough to produce the signal at the distant end,
and as the cable or wire is increased in length so does this difficulty
increase until you arrive at the limit where it matters not whether a
powerful battery of low internal resistance or a weak battery of high
internal resistance is used, the results being the same unintelligible
signals. Now when this condition is reached there is applied at the
receiving instrument a contrivance styled a magnetic shunt, which
consists of a series of electro-magnets so arranged that it is possible to
put in one or more electro-magnets in the shunt circuit, the terminals
of said shunt circuit being connected to line wire and earth, so when the
printing current acts upon or through the receiving chemical paper
commencing to record the signal it also acts through the magnetic shunt
charging the electro-magnets, and in doing this part of the current is

page_text: à
diverted from going through the receiving chemical paper, or in other
words the total current that arrives at the receiving instrument is split,
and in proportion to the resistance of the magnetic shunt so it is under-
stood that the amount of current going through the receiving chemical
paper can be regulated, thereby using but just enough current to produce
the signal at a given rate. But the great advantage of the magnetic
shunt is (as is well understood) that when battery contact is broken at
the transmitting end it allows the electro-magnets of this magnetic
shunt to discharge, and this discharge of the magnets takes place in the
opposite direction through the receiving chemical paper to that current
which made the signal. This being the case it follows that this discharge
of magnets cuts off this drag or prolongation of signals, producing
legible signals; but it only does this where the fall of potential is in the
same ratio as that of the line. But as it is almost if not quite im-
possible to secure this condition with the magnetic shunt in working
long circuits, and more especially long submarine cables, the signals or
dots and dashes are liable to run together, thus rendering them entirely
unintelligible. If the leak or resistance before mentioned between wire
and carth at the transmitting instrument be used in connection with the
magnetic shunt at the receiving end over a given circuit the signals will
be better than if one or the other is used alone, but the limit is soon
reached when the signals become imperfect and unintelligible.
In double current systems, as ordinarily used, the results arc less
satisfactory than that of single currents with the aid of the magnetic
shunt and leak at the transmitting end. In working double currents
the same difficulty is experienced in making dots and dashes as in single
currents, the wire is charged unequally and the effect is as before, dots
and dashes run together. But better results are got by sending a strong
initial current to line followed by insulation in case of making a dash
and then a reverse current to cut the dash as it were the right length,
or in other words cut off the drag; this is technically termed intermittent
currents, the object of it being to have the currents for making the dot
and thic dash of the same strength and duration. But in short circuits
to accomplish this object the signals have to be transmitted so slowly
that there is no advantage gained. In longer circuits or where the
static capacity of line is great and this system is used, it is found that
the printing current will be in excess; for instance, in transmitting "R"
(dot dash dot) no current having been sent during the latter part of the

page_text: preceding space the line wire is clear and receives a full charge from the
marking current for the dot, the following reverse current is immediately
succeeded by a marking current for the dash, and during the remainder
of the dash no current is sent to line. Two marking currents are thus
sent to one reversal, and the tendency is for the dot and dash to run
together because the marking current to commence the dash being
followed by insulation charges the wire to such an extent that it cuts
the reversal or neutralizes it so quickly that it has not time or is not of
sufficient strength to cut off the drag of the dot. In the case of the dot
following the dash the reverse occurs owing to the long interval since
the marking current was sent the line has become nearly nil, so when
the reversal is sent to cut the drag it charges the wire so highly that
the marking current to make the dot is shortened, and a reversal being
sent immediately after cuts the dot so quickly that it will be out of
proportion with the other signals, in fact two reversals being sent to one
marking current.
It is
There is another appliance used at the transmitting instrument; it is a
large resistance placed between battery and line, said resistance being
adjusted to conditions of line, and so manipulated that when a current is
sent to line of one name by means of transmitting instrument making
battery contact this same current still passes through the resistance
when battery contact is broken, and continues until the transmitting
instrument sends a reverse current, it acting through the resistance in
same manner as before; in fact there is always a current to line.
understood by this that the current through this resistance will of course
prolong the dash after the initial current is sent, but the same objection
exists as before; there is an inequality of charge. It is in fact sending
permanent currents or double currents, as it is called, with the exception
that two-thirds of the current is weakened in comparison to the first
third, for during two-thirds of the time employed to make the dash the
current has to act through a larger resistance in addition to that of
the line; this is styled sending compensating currents.
Now the difficulties in the above-mentioned plans of transmitting
telegraphic signals are capable of removal to a great extent by adapting
my Invention thereto, it being thereby possible to work over long
circuits, submarine cables, and underground wires at a much greater
speed than is accomplished by the existing systems.

page_text: I will first describe the application of my Invention to the system of
working chemically recording telegraphs, in which a permanent leak is
relied on for the purpose of clearing the line wire between each signal of
static electricity.
Fig. 1 shews two transmitting and receiving instruments connected to
opposite ends of a line wire or cable, and Fig. 1 is a side elevation of
one of these instruments. In their general construction they are similar
to those in common use for transmitting and receiving messages
-automatically, but in this case there is applied thereto three insulated
transmitting pens or styles set abreast of cach other, and in connection
therewith I use a strip of perforated paper, similar to that shewn at
Fig. 1'.
A is the transmitting drum, formed of metal and rotated by clock-
work or equivalent motive power. Bearing upon this drum are the
three contact points, pens, or styles, a, b, c, connected respectively with
the binding screws 1, 2, 3, which have wires secured to the battery and
carth. B is the receiving drum, which is similar to the transmitting
drum, but is fitted with but one pen or style d. The office of this pin
is to record signals upon chemical paper in the usual manner; the trans-
mitting pens or styles are manipulated by the strip of perforated paper,
'Fig. 1', the perforations being peculiar in their arrangement. The three
pens are insulated one from the other, each pen performing its work
independently of the others. To enable this arrangement to work single
currents, putting the line to earth between each signal, the wires leading
from the pen or style c, which is the compensating pen, and from the
pen a, which is the printing or marking pen, are connected together by
a wire, so that electrically the two pens become one. These connected
wires are united to one and the same pole of the battery, a wire from
the other pole of the battery being led to earth. The middle pen or
style b, which I call the reversing pen, is connected to earth by a wire of
no appreciable resistance. The line cable or underground wire is
connected through the standard C to the revolving drum A of the trans-
mitting instrument.
It will now be understood that the signals to be transmitted being
first perforated upon the strip of paper, Fig. 1, the lower row of
perforations will work the printing pen or style a, the middle row of
perforations the reversal pen b, and the top row of perforations the

page_text: b
compensating pen c, that is to say, as the printing pen a drops through
the lower perforation it commences the signal by connecting the battery
to line. When the printing pen rises out of its perforation the com-
pensating pen c drops into its perforation supposing it is a dash
that is being transmitted. This continues the signal up to a certain
limit, when the printing pen again drops through a perforation, pro-
longing the signal the length of the perforation. As the printing pen
rises out of one perforation the reversing pen 6 drops into another, thus
putting the line to dead earth for a given time. This allows the wire to
discharge rapidly, and at the receiving end the magnetic shunt is brought
into action, and as the line wire discharges rapidly at the transmitting
end the magnetic shunt has so much less work to do. Thus over a given
circuit this magnetic shunt will, by having dead earth put on to line
after a signal at the transmitting end, be more effective in cutting off
the drag than in the old way of working with a leak. I also get the
full strength of my battery to make the signal, and at the receiving end
the maximum effect of the magnetic shunt. This is very important
where it is necessary to use low battery power and on circuits where the
static capacity is great.
Fig. 2 shows the application of the Invention to the system of
transmitting signals by means of simple reversals. The compensating
pen c and printing pen a are connected together as in the former
instance, and are worked by a strip of perforated paper as before
described; but in this case the reversing pen b is connected to the
reverse pole of the battery, and thus when it drops into a perforation a
reverse current is sent to line. To accomplish this I prefer to arrange
my battery as shewn, having the centre of battery put to earth, using
the extreme zinc pole to print, and the extreme copper for the reversal.
A resistance coil may be placed between the printing and compensating
pen, as shewn by dots at D in the Figure, for the purpose of sending
compensating currents. It will be seen that when the compensating
pen drops into a perforation (which only occurs when making a dash) it
will send a much weaker current than that sent by the printing pen, or
in other words the printing pen sends a strong initial current to line
followed by a weak current (which can be regulated by the amount of
resistance introduced between the two pens) of same denomination; this
prolongs the signal up to the limit when the printing pen again enters a
perforation; this will have the effect of governing the wire as it were,

page_text: and only allowing the potential to fall to a certain extent. The weak
current from the compensating pen would not alone be sufficient to
prolong the signal, but serves to control the static condition of the line,
and prolong the signal to a certain limited length. This obviates the
necessity of having the full strength of current to line in making a dash,
and thereby charging the wire to a greater degree than is required for
making a dot. When the printing pen drops into the last perforation of
the dash it sends the current of full strength, so as to make the dash of
sufficient length; but in doing this the wire does not become so highly
charged as it would have been if the full strengh of current had been
sent throughout the signal, as in the previous case, where no resistance
was interposed between the printing pen and compensation pen, the
current which makes the dash charging the wire little if at all more
than that which makes the dot, and the reversal being sent immediately
after the signal to discharge the wire, thereby cutting off the drag. This
plan allows of faster working over a given circuit than the present
system of compensating currents, for the reason that the compensation
has only to make one-third of the dash, and the initial current will not
have to charge the wire to so great an extent as in that system where
the compensation has to make two-thirds of the dash, it being then
necessary to transmit slowly enough to have the initial current
sufficiently strong to charge the wire in proportion, the peculiarity of
my plan being that I send a strong initial current followed by a weaker
one, termed compensation, in the same direction, and then for the last
third of the dash I send another current in the same direction as the
initial current, followed by a reversal, the compensation making only
the centre of the dash. Of course it is understood that I only have
reference to those circuits where this peculiar form of compensation can
be employed with profit, either on other systems or my own, the arrange-
ment of battery being the same as before.
I will now describe an arrangement by which I gain the advantage in
chemical telegraphy of having the currents that make the dash of the
same duration as that which makes the dot, the static electricity of the
line wire being utilized to make the centre of the dash, by filling up the
interval which occurs between the two currents, in the same direction,
which are sent to make the dash. In this case, as before, it will be seen
that by depending upon the static electricity to make only one-third of
the dash I can transmit telegraph signals much more rapidly than

page_text: where the static electricity is depended upon to make two-thirds of the
dash, as I do not have to charge the wire so high with my first initial
current. I also derive another advantage by having the resistance
between the compensating pen and earth adjustable, as I obtain a larger
margin to work upon; for instance, if the resistance is too small and
discharges the wire so quickly at a given speed of working that the dash
is weak or split in the centre, I can add more resistance until the dash is
made perfect in the centre at the same rate of speed as before, and vicè
versa, the commencement and end of dash always being full.
In the arrangement shewn at Fig. 3 the pins or styles a and b I
connect with opposite poles of the battery, and the compensation pen or
style c I connect with the earth, interposing a resistance coil D. The
'perforations in the ribbon (see Fig. 1b) are so arranged that one only of
the pens shall be in contact at a time with the metal drum of the
transmitting instrument. When making a dash I send first a strong
initial current to line through the pen a, and thereby charge the line
wire to a high potential. When the pen a breaks contact with the
drum A by reason of a solid portion of the ribbon coming under the pen
the compensation pen c drops into contact with the drum, a perforation
of the travelling ribbon being brought under it. This has the effect of
clearing the wire of static electricity (the said pen being connected to
earth). If however no appreciable resistance were interposed between
this pen
and earth the wire would discharge in so short a time that there
would be only a dot produced at the receiving end. But by introducing
a given resistance, as at D, between the pen and earth the discharge of
the wire will be retarded sufficiently to ensure the prolongation of the
signal at the receiving end up to a certain limit. To finish the signal
or dash a second strong current is now sent to line through the marking
pen a, and this is instantly followed by a current to line in the opposite
direction, caused by the reversing pen dropping into a perforation in
Ն
the ribbon.
In circuits that have great static capacity, and that will dischargo
through the compensation pen and wire to earth during the interval
between the two initial currents that make the dash, this arrangement
may be used without the resistance coils between compensating pen and
carth (it being supposed that the wire connecting compensating pen to
carth has no appreciable resistance), a reversal being sent immediately
after the last initial current.

page_text: '
Fig. 4 shews an arrangement for sending reversals of varying strength,
as may be required in centre of dash, the printing and reversal pens
being arranged as in Fig. 3. The object of this arrangement is to enable
me to work over circuits where the static capacity is so great that the
means just described will not discharge the wire during the interval that
occurs between the two currents in the same direction, which are used
in making the dash. The compensating pen in this case is connected
through the adjustable resistance D to the reverse pole of the battery.
Now in making a dash the printing pen sends a current to line com-
mencing the dash. Immediately upon the printing pen rising out of
the perforation the compensating pen drops into a perforation, sending a
reverse current to line. The strength of this reverse current is determined
by the amount of resistance introduced between the battery and pen,
and the amount of resistance to be introduced is determined by the
static capacity of the line, the object being to have the resistance such
that the current through it to line will discharge the wire at the point
where the printing pen again drops into a perforation, sending the
second current for the dash, instantly followed by a full reversal. In
this mode of working I use as before currents for making the dash of the
same strength and duration as those which make the dots, thus charging
the wire equally in making dots and dashes.
It will be obvious to clectricians that all which is accomplished by
the three insulated pens may also be effected by three drums insulated
the one from the other, and corresponding to the three insulated pens
before described, in which case the transmitting pens would be all
connected together, forming one which would be connected to the line
wire. But I prefer the three insulated pens as being more simple in
arrangement.
I would remark that the manner of piercing the strip or ribbon used
to work the three pens or styles may be modified to suit varying
circumstances.
In Fig. 1, which has been referred to throughout the foregoing
description, the ribbon is shown as pierced to transmit the word
"printed." When the static capacity of the line is great, and it is
desirable to put the line wire to earth between each signal, as well as on
the middle of each dash, I use the strip or ribbon shewn at Fig. 5.
This Figure shews the letters a, b, c, d, e, as perforated for transmission.

page_text: Having now set forth the nature of my Invention of "Improvements
in the Mode of and Apparatus for Transmitting Telegraphic Signals,"
and explained the manner of carrying the same into effect, I wish it to
be understood that under the above in part recited Letters Patent I
claim in working chemically printing and recording telegraphic apparatus,
the use of the three pens or styles a, b, c, or their equivalent in com-
bination with a ribbon perforated as above described, whereby I am
enabled to put the line to dead earth after each signal transmitted to
throw a weak current (reversed or otherwise) into line following a
strong initial current, or to obtain compensation from the statical
electricity of the line wire for the purpose of increasing the speed of
transmission, and the legibility of signals sent and recorded by chemically
printing telegraphic instruments.
In witness whereof, I, the said James Wallace Brown, have here-
unto set my hand and seal, the Fourth day of December, in
the year of our Lord One thousand eight hundred and seventy-
four.