Improvements in Apparatus for Electrical Sound and Sight Signalling on Railways and other Lines of Rail.
Year: 1891

page_text: Date of Application, 25th July, 1891
Complete Specification Left, 11th Sept., 1891-Accepted, 7th Nov., 1891
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Electrical Sound and Sight Signalling
on Railways and other Lines of Rail.
We, ARCHIBALD DRUMMOND MACDONALD, of Number Twenty-six Spellow
Lane, Liverpool, in the County of Lancaster, Doctor of Medicine, and JAMES
DODD, of Number Twenty-two Weldon Street, Walton, Liverpool aforesaid,
Millwright, do hereby declare the nature of this invention to be as follows :--
An electrical apparatus by means of which an engine, train, or portion of a train
or any vehicle on the railway, or other line of rails, which has two wheels at least,
joined together by a metallic axle or other metallic connection, (the said rails being
laid on sleepers which are of wood as usual, or are insulated from earth connection
if required), automatically communicates to the station or stations in advance and
in rear, or advance, or rear only, by means of sound and sight signals, the fact of
its arrival near to, or at, a given station; also, if passing onwards towards another
station, its departure from the given station; and further, during the whole time
occupied by the vehicle or vehicles in passing from the given station until their
departure from the station in advance (with a single exception after-mentioned), an
indicating part of the apparatus will demonstrate to the signalmen of the station
left, and that to which the vehicles are proceeding, that such vehicle is present on
the section of the railway, referred to. The passing over of any intermediate fixed
point may also be signalled separately. Also, the distance of the train from either
station at intervals, or at any moment, and therefore its speed, can be shewn.
The apparatus can be electrically tested as to its working condition by a key or
switch, which is also to be used for the giving of necessary code-signals. Switches
are applied to enable the apparatus to be worked in sections when required, as for
repairs.
The whole is under the signalman's control and constant knowledge of its right
working.
More particularly, in the first place, the rails themselves are utilised for contact
purposes by forming "rail-sections of contact." This is done by insulating a
portion or portions, which may be of any required length, of either rail, in such
manner and position as to fit the insulated portion or portions for taking part in
giving "arrival," "departure," "speed," "distance," and other notifications of
signals: this insulated portion forms one of the contact poles. The corresponding
rail opposite forms another part of the circuit either in its ordinary entire and
continuous condition-fitting it for being used as a conductor, or, a suitable and
insulated portion employed, or, it is simply connected with the earth when the
source of electricity (battery) has directly or indirectly a similar earth connection
or earth-plate. Then, when any two metal vehicle-wheels, connected by a metallic
axle, or linked by another conductor, pass on to the insulated portion and its corre-
sponding rail opposite, the contact is "made" and the signals given for that part of
the circuit: on the contrary, when the wheels pass off the "rail-section of contact,"
the circuit is broken and these signals cease.
This principle of using insulated portions of the "working-rail" or rails for
contact purposes, may be applied in various ways, and to coal and other mines, and
tramways, as well as railways. Alternatively, a switch arrangement, like a points
with contact-maker may be used.
Secondly. A lever-contact arrangement is employed in connection with one or
more of the signal-levers in the signalman's cabin. This consists of divisions
corresponding to the positions at "danger," and "clear" or ❝ caution of the
distant, home, or starting and "advanced" starting, signals, and also of a test

page_text: division which is concerned in the notifying of change of position of the signal
lever, and, at the same time, giving a working-test for the circuit. These divisions
have contact made by a metal bridge with wheels or rollers suitably placed, or
simply a plain sliding piece of conducting material is employed-no insulation of
the parts of the bridge or contact-maker being required. This contact arrange-
ment may be placed in any convenient position with relation to the signal-lever
or levers, and if not fixed directly to the lever-handle and bracket above or below,
or fixed to the lower end of the lever, then it (the contact arrangement) will be
connected by rods, cranks, or chains with the signal-lever.
Alternatively, when such a source of electricity as the bichromate battery is
used, the lever-contact may be made or broken simply by a rack and pinion
direct-acting, or lever indirect-acting arrangement for raising or lowering out
of the fluid in which immersion is requisite one or both of the cell elements.
Or, the lever-contact described in Complete Specification under Patent granted
to us, No. 1214, A.D. 1890, may be here employed.
The distant, home and starting, or advanced-starting signals may have their
levers variously arranged on circuit in signal-giving under this invention.
Thirdly. An electric bell or sound-signal may be used to indicate whether the
home or starting and advanced-starting signals be " on or off."
"
66
Fourthly. In the signalman's cabin or cabins are a "continuous "-stroke, and
also a single-stroke bell, gong, or sound-signal. Both are connected with the
sound-signal or signals at the distant station or stations. This distant station
sound-signal (if only one be there used) will be "single-stroke," but it is capable
also of giving a "continuous" sound when connected with the continuous-stroke
sound-signal above-mentioned. An indicator may be employed in connection with
any of the sound-signals to shew that it has been in action.
Fifthly. The fog-signal under our Patent above-mentioned may be attached to
the apparatus herein-described, by an appropriate switch, or connection.
Sixthly. All, or any, of the sound-signals may be actuated by a compound electro-
magnet in the motor form, instead of a simple electro-magnet.
Seventhly. A conductor separate from the "arrival" rail-section, or sections of
contact intermediate between two "departure" rail-sections of contact, connects
what we term the "non-insulated" portions of rail on either side of that section of
contact. Then, either to that rail, or to the opposite, an automatic index in the
form of a galvanometer, telegraph needle, "single-stroke" "held-down" bell or
lever, or other sight-signal of suitable construction, which may be capable of
being illuminated when required, and may be so placed as to be visible to any
person on a train, as well as to the signalnan, is joined by a conductor of
electricity a battery and earth-plate, or other such arrangement, is fixed to the
other end wire of the sight-signal. A similar sight-signal is attached to the
opposite rail from the attachment of the former sight-signal, at the station in
rear, but only the earth connection and no battery is there required. Any
breach of electric continuity, as from points or sidings, is also bridged-over as
indicated above for the rail-sections of contact. Then, when a train, or part
thereof, or a surfaceman's trolley, goes on the section of railway between
"departure
contacts (except a brief "break" of circuit when a short train or
single vehicle is passing over a long rail-section of contact,) the index at both
stations shews that the section of railway is "blocked." When the nearest point
of "departure" in advance is passed, the automatic index shows "section of
railway clear." The circuit is from battery to sight-signal, along one rail, across
the engine or vehicle, along the other rail to the other sight-signal, thence by
earth to opposite pole of battery.
"
Alternatively, the above-described automatic index arrangement by itself, or in
combination with the distance indicator referred to below, under heading "Eighthly,"
may also be constructe by using two batteries, one for each index, instead of a
single battery for both indices. The indices are connected at each station with
both rails. At the station in rear there is a break in the circuit of the index

page_text: belonging to it, which break is again "made" when one of the signals (the starting-
signal preferably) is placed at "danger." A distance indicator may be put in the
same circuit near to the automatic index above-described in each signal-cabin. Or,
the "index" may be replaced by an electric contact-maker or switch caused by the
current to make the contact for actuating a motor in moving a larger index or
sight-signal.
Eighthly. The indication of one or more known distances in the position of the
train between stations may be obtained, and therefrom the train-speed ascertained,
by using one or more intermediate rail-sections of contact and connections.
Alternatively, an arrangement may be employed, such as a Wheatstone's bridge
with resistance coils (and the battery being constant), for the purpose of shewing
the distance away which a train on section, or trolley, is from a station.
Ninthly. A switch or key will be employed by the signalman for the purpose
of affording an additional test to that supplied by the signal-lever contact
movement, as to the working condition of the circuit, or portion thereof in action
for the time being.
Tenthly. Switches are used to connect and disconnect the various parts of the
apparatus at pleasure.
Eleventhly. The electricity employed may originate in batteries, accumulators,
or dynamos.
Twelfth, and lastly. The various portions of the apparatus are connected by
wires, or other conductors, to each other in such manner as to fulfil the purposes
and objects above-specified, or any further purposes of signalling to which the
apparatus may be applied.
Dated this Twenty-fourth day of July One thousand eight hundred and
ninety-one.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Electrical Sound and Sight Signalling
on Railways and other Lines of Rail.
We, ARCHIBALD DRUMMOND MACDONALD, of Number Twenty-six Spellow
Lane, Liverpool, in the County of Lancaster, Doctor of Medicine, and JAMES
DODD, of Number Twenty-two Weldon Street, Walton, Liverpool aforesaid, Mill-
wright, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
An electrical apparatus by means of which an engine, train, or portion of a
train, or any vehicle on the railway, or other line of rails, which has two of its
wheels at least wholly or partially constructed of electrically conducting material,
and having the conducting wheels or parts of wheels joined together by a metallic
axle, or other conductor independent of the axle, the rails being laid on wooden
sleepers as is usually at present the case, or, if otherwise, necessary insulation of
them to be practised,-automatically causes to be communicated by means of sound
and sight signals, to the station or stations in advance and in rear, or advance or
rear only, the fact of its presence at any intermediate point that may be fixed
upon, and also near to, or at, a given station; and further, while the vehicle or
vehicles are passing from one station to another, an indicating part of the apparatus
will demonstrate to the signalmen of the station left and that to which the vehicle
or vehicles are proceeding that such vehicle is present on the section of railway
referred to, or on any portion or portions of such section. Also the distance of the
train from either station at intervals, or at any moment, and therefore its speed, is
shewn.

page_text: The apparatus is electrically tested as to its working condition at any time by a
key or switch, which is also used for giving necessary code-signals.
The whole is under the signalman's control and constant knowledge of its right
working.
Having stated the general idea and purpose of the apparatus, our description
now ranges itself into four divisions: (1) The individual parts of the apparatus
and their uses; (2) the sound-signalling parts: (3) the sight-signalling parts;
and (4) examples of circuits.
Firstly. The permanent rails are utilised for contact purposes by being
apportioned into "rail sections of contact." This is done by insulating a portion
or portions (which may be of any required length, and, practically, will be of such
varied lengths as will give variety of signal) of either line of rail, so as to fit the
insulated portion for acting as one of the poles in a "break" of the circuit as
shewn in Diagram I, where R. s. c is the insulated "rail section of contact,"-I the
insulation, W the wire attached to this pole of the contact,-w the wire attached
to the corresponding rail opposite (C. r. o),—and R, R, the remainder of the line
of rails between which is the "rail section of contact,"--which "remainder" is
concerned with the sight-signalling parts after-mentioned. T is a pair of wheels
on the contact; a pair on "remainder." One method of accomplishing the
insulation referred to is shewn in Diagram II, Fig. 1.-of which Fig. 2 is a vertical
transverse section. Insulation is there represented as done by substituting, for the
ordinary form of fish-plate at the abutting ordinary rail-ends, or ends purposely
nade with shorter or longer rail lengths, the form of fish-plate (f. p.) shewn in the
diagram. Here, after placing round the rail-ends (R. c,) a piece of insulating
material (I) such as asbestos cloth, india-rubber, compressed paraffined paper,
"vulcanised fibre," or a shaped insulator, as of ebonite, and also inserting between
the rail-ends (r. e.), another piece (i, i) of the insulating material, the fish-
plates (f. p. 1 and f. p. 2) which have a key-bed slot (k. b. s.), are applied, and
bolted together below the insulation by the bolts (b, b, b, b). In Diagram II, R is
the rail, C the ordinary chairs; and S the sleepers.
The corresponding rail opposite (C. r. o, Diagram I) forms another part of the
circuit, either in its ordinary entire and continuous condition, or through its
continuity as a conductor of electricity being ensured by bridging over any breach
of that continuity, as at points or sidings, in the manner shewn diagrammatically
in Diagram I for bridging the rail-section of contact, by a conductor fastened to
the adjacent ends of the breach (see CO, CO, CO).
And when a breach is caused by a part of the line being broken up, or under
repair, the breach is bridged by a suitable conductor being clamped or clipped on in
like manner to the rails, at the beginning of repairing operations.
Then, when any pair of wheels (T, Diag. I) with axle as above-described, passes
on to the insulated portion, and its corresponding-rail opposite, the contact is made
and the signals given for that part of the circuit; on the contrary, when the wheels
pass off the "rail-section of contact" the circuit is broken, and these particular
signals cease, but the signals given by the automatic index after-described continue
or are resumed after a brief break corresponding to the length of a rail-section of
contact nearly, in the cases of the contact being very long or the vehicle very
short, (Diag. I. t.).
Alternatives I. In insulating the rail-ends, the ordinary fish-plates may be
retained, a piece of insulator inserted between them and the rails and also between
the rail-ends, and, in addition, the bolts insulated from fish-plate and rail by a
ferrule of insulating material.
II. Any method of insulation of the "rail-sections of contact," and any insulating
material, or no insulating material, may be used. Insulation may, for example, be
secured by safely fixing the rails, and simply leaving a short gap open at both ends
of the rail-section of contact.
III. Corresponding portions of both rails may be employed in forming rail-
sections of contact.

page_text: An earth circuit, for example, by earth-plate and wire to the corresponding rail
opposite (C. r. o. Diag. I) may be employed when the source of electricity is
directly, or indirectly through the "return" division of the lever-contact after-
mentioned, connected with the earth.
IV. The principle of using insulated portions of the working-rail or rails for
contact purposes may be applied in various ways, and to rails in coal and other
mines, and tramways, as well as railways.
66
"
Secondly. A lever-contact arrangement (Diagram III) is employed in connection
with one or more of the signal-levers in the signalman's cabin It consists, as the
form represented in Diagram III shews, of a return division (R d. c) which
co-operates with the other divisions of the contact; of a division (D. d.) corre-
sponding to the positions of the distant, home, starting or advanced-starting signals
(to whichever the lever-contact may be attached) at "danger," at "clear
caution "the "clear" division (Cd); and also of a test division (t. d.) which
is concerned in the notifying of change of position of the signal-lever, and at the
same time giving a working-test for the circuit. In the Diagram III these
divisions are shewn in a vertical longitudinal section (Fig. 1); and in plan
(Fig. 2).
or
An end elevation of the contact is shewn in Fig. 3, as from the front of the
carriage in Fig. 1.
The bed (i. b) in which these divisions are laid is a non-conductor which
insulates them from each other, and from the material on which itself is fixed.
These divisions have "contact made" by a metal bridge (m. b), with two pairs of
metallically connected wheels or roller contacts (w. r. c.), placed so that the first
pair make contact between the divisions R. d., c and D. d. when the signal is at
"danger," the second pair, between R. d., c. and C. d. when at "clear," and one
of each pair on the "test division" side makes the test contact when the signal-
lever is moved from danger to clear, or the opposite. A carriage (C. m b) with
two gab-bearings below for the reception of the axle of the rollers, and running in
the guide (g.) above, moves these rollers. No insulation of the roller contacts
from each other is practised.
▲ differential arrangement of rods and levers (d. c. r Fig. 1) connects this
carriage and its roller-contacts with the signal-lever (S. J. of Fig. 1) at the bolt (b).
Br points out brackets for the guide (g).
Alternatives. 1. A plain sliding piece of conducting material may be used instead
of the contact carriage and rollers.
II. The lever contact described in the Complete Specification under our Patent
No. 12104, A.D. 1890, may be here employed.
III. When such a source of electricity as the bichromate battery is employed,
the lever contact for "danger" or "clear" may be made or broken simply by a
rack and pinion direct-acting, or lever indirect-acting, arrangement for raising or
lowering one or both of the cell elements out of or into the fluid in which immersion
is requisite.
IV. As to the situation of this lever-contact arrangement, it may be placed in
5 any convenient position with regard to the signal-lever or levers, and if not fixed
directly to the lever-handle and bracket, above or below, or if fixed to the lower
end of the lever, then it (this lever-contact arrangement) will be connected by rods,
cranks or chains (as in Diagram III Fig. 1) with the signal-lever.
V. The distant, homie, starting and advanced-starting signal-levers and their
contacts may be variously arranged on circuit in signal-giving.
VI. The "test" division may be dispensed with, in which case the wire from the
departure contact will pass to the arrival contact, and the wire m dw (Diag. VII)
would be led first to the signal indicator (s i) in the signal-cabin, and thence to
the wire from departure contact to arrival contact to which we have referred above.
Thirdly. An electric sound-signal, instead of a mechanical sound-signal, may be
used to indicate whether the home or starting-signal be "on
" "off."
Fourthly. In the signalman's cabin are a "continuous" stroke or "trembler;"
ΟΙ

page_text: and a single stroke bell, gong or other sound-signal: these are referred to under
description of the circuit for sound-signals. The former comes into action in
"danger" sound-signalling; the latter, when "clear" is given. At the distant
station, there may be two bells or sound-signals to act as receivers for the two just
mentioned; but, if only one sound-signal be there used as a receiver, it will be
"single-stroke," as it is thereby fitted for acting in concert with either the continuous
or single-stroke sound-signal above referred to.
Fifthly. The danger sound signal under our Patent (No. 12104, A.D. 1890)
above-mentioned, which is to be used during fog, falling-snow, repair of line, and
may also be used for other purposes such as for protecting of trains while shunting
at stations, is to be attached to the apparatus herein-described by an appropriate
switch, or connections such as those hereinafter described.
Sixthly. All, or any of the sound-signals may be actuated by a compound
electro-magnet in the motor form instead of a simple electro-magnet.
"
or
Seventhly. The rail-sections of contact being bridged over, in the manner before
referred to, by conductors connecting what we term the "non-insulated "
"remainder" portions of rail intermediate between two of what are hereinafter
briefly called "departure contacts (Diagram VII D. c., d. c.) [these portions,
however, being electrically continuous and capable in themselves of acting as
electric conductors]; then, at the near station (A, Diagram VII) an automatic
index on the principle of the galvanometer is placed (AI); this is attached to a
battery (b) on the one side, and to one rail (R. R.) on the other, by being
connected to one division of a starting-signal contact (s. s. c. 1, Diagram VII)
"made" at "danger," which division has prolonged to it what is in effect the half
(p. c. d, 1) of one of the conducting bridges above-mentioned, from the "arrival
contact." The other division of the starting-signal contact has the remaining
half (p. c. d. 2) of the virtually prolonged "bridge" attached to it.
"
"
At the far station (Z) there is another automatic index which works in circuit
with the former by having one of its attachments (Diagram VII w. t.) to the rail
opposite to that to which the other index is attached, the other attachment being
to the opposite pole (o. p. B) of the index & battery (A 1 & b) through earth or
wire. Then, when a train, or part thereof, or a trolley, enters, or is present oll,
the section of railway lying between "departure contacts (except the brief
interval under conditions before-mentioned) the indices at both stations shew that
that section of railway is "blocked." When the nearest point of the "departure
contact in advance is passed, the indices shew section of railway to be clear. The
mode of action of the starting-signal contact" is that it fulfils the purpose of an
electrical switch for the automatic indices in the following manner: As, when the
starting-signal is at "danger," the contact referred to is "made" (switch closed'),
the circuit of the indices remains "closed" while a train is passing from one
station until it is departing from the station in front, as before explained; but, if
the starting-signal be lowered (as it is in practice, e.g., to allow an express train to
pass) then the circuit is broken as soon as the train passes the insulated point; in
the vicinity of the distant signal, and the automatic indices consequently move
from "line blocked" to "clear"; thus a following train is permitted to enter the
section of line earlier than when the indices shew "blocked" until the former
train has "departed" from the station, above referred to as the 'station in front.'
I. The automatic indices may take the form of an electro-magnet and armature,
as in a single-stroke bell, the armature being held down through the action of the
current, while the train is passing from point to point above-mentioned.
II. The above-described automatic index arrangement by itself, or in combina-
tion with the distance indicator referred to below under heading Eighthly, may be
constructed (Diagram IV Fig. 1) by using two batteries (b, b¹), one for each
index (A I, à i), instead of a single battery for both indices. The indices are
connected directly, or by earth circuit (E. c. p.) at each station with both rails,
and are connected with the starting-signal in the manner above indicated. T is
the train & the arrows shew the direction of the currents.

page_text: III. The automatic index may be employed as a switch to make and break a
short circuit at each station. The short circuit or circuits will consist of a battery
and also of an electro-motor to actuate the working-signals on the line in this way,
that, when a train is on section, although both indices shew blocked, the blocked
side of the index at the station to which the train is proceeding is switched to the
"signal off," and so "clears" the line, but, at the station in rear, the signals are all
similarly raised to danger so as to protect the train referred to.
IV. The automatic index may be applied, to loop lines or sidings by insulation
of one or both rails at each junction of the loop with the main line, or at the
junction of siding with main line as required.
Eighthly. The following arrangement (Diagrams V, VI and VII) is used for
signalling the position of a train, and its rate of speed, from a fixed portion (called
the "mid-distance") of the line between stations, as in Diagram V M D., m. d.
Two pairs of rail-sections of contact (1 and 2, & 3 and 4), fixed at the determinate
distance of, for instance, a mile or a quarter of a mile between the first entered-on
end of one of a pair, and the corresponding end of the other contact of the
same pair, may be employed: two of these (3 and 4) are connected with the
arrival contact of the station (Z) immediately in advance: the remaining two
(which are the first contacts connected with the mid-distance signal now under
description) [1 and 2]. are connected with the mid-distance contact for any
station (A) still further in advance. Thus the connection is from the mid-
distance contacts 1 and 2 between stations Z and Y (Diagram V) to the mid-
distance contact 3 and 4 between Z and A, or to those of any other station.
The effect of this is, that a train passing over the "mid-distance" automatically
signals by sound its being on that part of the line, and also indicates, as about to
he described, the speed at which it has travelled over the part referred to. The
signalmen at two or more stations, as the case may be, in advance of the train are
thereby warned of its approach; also station Z is warned.
Alternatively, the ordinary mid-distance contacts placed between stations, and
consisting of two rail-sections only, may be employed, and the advanced mid-
distance contacts, and their connecting wire to the ordinary mid-distance may be
omitted.
The indicator for speed is constructed as in Diagram VI, and it may be attached
to any ordinary clock or timepiece in the signal cabin, or be specially constructed.
The diagram shews a pendulum (P.) acting on the escapement (E), and this
noving a wheel (W), which may be the seconds wheel of the clock. On the same
axle as this wheel is a friction-wheel. Corresponding in time movement with this
friction-wheel is another friction-wheel (F W) on a prolongation forwards of
whose axle is fixed, in front of the dial mentioned below, a pointer, the object of
which is hereinafter stated. In case of attachment of the speed-indicator to an
ordinary clock or timepiece, the axle just referred to will be made to pass through
a slot in the clock-dial, sufficiently large to allow upward movement of the axle
when the magnet e in 2 pulls the friction-wheel (FW) out of gear; and the
lower end of the slot will be the centre of a circular graduated scale or dial
shewing the rate of speed of a train in miles per hour according to the number of
seconds or minutes which it occupies in passing over the mid-distance contacts
before-described. Thus, with one mile between the mid-distance contacts, and the
friction-wheel (W) in gear for one minute the train speed would be indicated by
the pointer on the graduated dial, as sixty miles per hour, two minutes equal to
thirty miles per hour and so on. The scale or "dial" may be painted on the
clock dial, or may be a separate dial fixed to the tumbler-armature, or indepen-
dently may form part of an indicator whose pointer, when "in gear," is moved by
the action of its own clock work. The pointer indicates on the dial "miles per
hour," the time occupied by the train in running the distance between contacts, or
in running a definite distance, as one mile (and fractions of these similarly).
There is a tumbler (tu) with an armature-ending (a), and two electro-magnets,
one on each side, (E m 1 and e. m. 2). The tumbler moves on the stud (st) and a

page_text: prolongation (p. c.) makes contact with the wire-end contacts (W E C and we c)
according as the current passes through one or other electro-magnet. The mode
of action is, that when the train passes over the first of the mid-distance contacts,
which may be represented as 1 (Diagram V), (in the case of case of advanced
mid-distance signalling being desired), the electro-magnet (E m. 1) attracts the
armature (a) and causes the friction-wheel (F W) to fall against the clock friction-
wheel, thereby causing the pointer referred to to move synchronously with the
clock when the train passes over the fellow mid-distance contact, 2, in this
instance, the friction-wheel is lifted up by the attraction of the armature by
electro-magnet (e m. 2), and is, by the tumbler weight, passively retained there,
when the current ceases until the train has reached mid-distance contacts 3 and 4
of the station (A) beyond, when a repetition of the signal takes place. In
turning back the pointer, a contact is made which is connected with the same wires
as is the "test" key or switch (Diagram VIIT S) to be after-described, and this
will cause an acknowledgment" of the signal to be transmitted to station in rear
of that signalman, that is, to Z.
ני
Alternatively I: Signalling may take place from one "mid-distance contact
by using one pair only of rail-sections of contact.
II. When the alternative automatic-index circuit with the battery at both
stations is employed, a resistance-measurer, such as a Wheatstone's bridge with
resistance coils, may be placed in circuit, as at R M (Diagram IV), for the
indication of the distance of a train from stations in front and rear respectively.
Ninthly. A switch or key (T. S. diagram of circuits VII) is employed for the
purpose of affording to the signalman a test as to the working-condition of the
sound-signalling part of the apparatus additional to that afforded by the signal-lever
movement, and for giving necessary code signals. One of its poles is fixed to the
return wire (RW), and the other to the wire leading from the departure contact
to the "test" division of the lever-contact. A similar switch (A I. W.) may be
connected with the automatic index, one pole (p. 1.) being connected with the
wire (p. 1. w), and the other to the return wire just mentioned; when the line is
clear the test for "blocked" may thus be applied without a train being on the line.
Tenthly. In Diagram VII a switch (Sw B) is represented as being used to
disconnect the part of the sound-signal circuit leading to the station (B), and
another switch (S w. Z.) is similarly used for the circuit to station Z: these are
employed in practice when either part is under repair, through the earth-plates EP:
and wire (s. e. p).
An automatic switch (A S) is used for the danger sound-signal (D. S. S.). Its
circuit will be described below, but its action is, that when a train is standing at,
or moving on within the distance from distant to starting-signals, and another train
is following on the same line of rails, the danger sound-signal (D. S. S) will sound
for danger, whether the signalman has made the mistake of leaving the distant
sigual at "clear"
or not this switch is also an index for the part of the line
referred to.
Apart from, or along with, that automatic switch, the danger sound-signal is
brought into, or thrown out of, use by the mechanical switch (D. D. S.), and, if this
mechanical switch be used in conjunction with the automatic switch as is shewn in
Diagram VII (A S), it will consist of two parts insulated from each other at I,
the pivot being at the junction of the wire S. S. W. with the switch (DDS). The two
lower points of contact, pivot and that below it, belong to the ordinary danger
sound-signal circuit; the two upper points belong to the automatic switch
circuit.
Eleventhly. The electricity employed may originate in batteries, accumulators
or dynamos.
Lastly. The circuit connections of the apparatus are as follows:
11
(1st.) The sound-signal circuits, taking first the station to station sound-signal
circuit. may be described as beginning at the danger division of the lever-

page_text: :
other pole of which is attached by wire to the danger "test" sound signal (t. d. s.),
thence it is continued by the wire to the switch S w Z, and, crossing the switch,
the wire Zss is carried to the receiving sound signal (Z. s. s.) at the station in
rear (Z). Thence it (the circuit) is continued through the earth-plate (Z. E. P.)
to the earth plate (BE P) fixed to the sound-signal (B. s. s) of the station (B)
in advance thence it is extended by the wire B w to a rail-section of contact,
called the departure contact, near the starting-signal (S S. c) of station A (which
departure contact is used to notify, to stations in advance and rear, the departure
of a train from A); thence the wire is led to the "test" division of the signal-
lever contact (t d): from the said test division, a wire (T W) is led to one part
of the arrival rail-section of contact (A c), the position of which is beyond the
distant-signal (D. S.), and the use of which contact is to notify arrival at station A,
and to actuate the danger sound-signal, when necessary. [Part of this wire (D tw)
may be the same as that for the danger sound signal's attachment to the arrival-
contact.] The circuit is then continued by the bridges of the arrival contact to
rail-sections of contact 3 and 4, as in Diagram V of the mid-distance rail-sections of
contact between stations A and Z. In most instances, these contacts 3 and 4 will
alone be requisite, but, should an extension of "mid-distance" signalling be desired,
the circuit is extended from thence by wire to parts 1 and 2 of the mid-distance
contact farther to the rear, as, for example, between Z and Y.
The "clear" sound-signal circuit may be described as beginning at the clear
division of the lever-contact (C d),-being continued by wire to the one pole of
battery (b. c.), from the other pole of which the wire is led to the clear test sound
signal (t. c. s.), and that is connected with the circuit just described for danger by
the wire c W. The earth plate s E P and wires connecting it to the switches Sw B,
and S w Z only comes into circuit when either part of the circuit (to B or Z) is
temporarily disused.
The wire R W leads from the opposite line of rails (C. r. o. Diagrams I and VII)
to the return division of the lever-contact (R d., c.).
Then, for each and all of the rail-sections employed, the circuit is completed by
contact made through a pair of passing wheels, as before described,—the " corre-
sponding rail opposite" acting in continuity as part of the circuit between its portion
opposite the respective rail-sections of contact and the wire R W, R W, to the
return division of the lever-contact, which is bridged by the roller-contact as
above-described, and thus completes this circuit when the signal is in operation, as
before-mentioned.
Second. The danger sound-signal circuit begins at the danger division of the
lever-contact, is continued by wire D.d. w. to one pole of the battery (D. B.); from
the other pole the wire D. b. s. continues the circuit to the switch at DDS.
To this wire is attached, (represented as on a shunt), a small test-bell (D. t. s.).
The switch continues it to the pivot,. thence the wire (S. S. W.) is led to the
danger sound-signal (D S S) which the wire d. t. w. connects to the arrival-
contact (A c).
Crossing the line by a wheel and axle, the circuit. is completed, as was the
foregoing circuit; then, when the automatic switch is also employed, the
wire D. s. w. leads to one point of the switch contact (D DS); then crossing
the switch to the other point, this is connected by wire to one of the contact points
of the automatic switch. Across the automatic switch, the circuit is continued to
the other contact point, and thence by the wire a. s. w. to the wire R W leading to
the return division of the lever-contact. The battery (A B) for the automatic
switch has, from one of its poles, a wire to one of the rails, which rail is insulated
on the near side of the distant signal at i.
From the other pole a wire passes to the automatic switch, and thence leads to
the "corresponding rail opposite." The circuit is then completed by wheel and axle,
as before.
(2nd.) The sight-signals. First, the automatic switch above-described acts, as
has been mentioned above, as a local sight-signal.
:

page_text: Second. The "speed indicator" (Diagrams VI ; and VII, s i) is most effectively
placed on a wire (m. d. w Diag. VII) leading direct from the mid-distance contact,
but may be interposed in the circuit on the wire from test division to arrival
contact (T W Diag. VII), provided the mid-distance contact is itself connected
directly with the arrival-contact. Its own circuit is as follows (Diagram VI): the
wire w 1, (leading directly by the wire m d w, Diag. VII, or indirectly by the test
wire T W, from a mid-distance contact), is connected with an electro-magnet (Em 1);
thence it is led to contact point w. e. c.
From the wire w 1, a short branch (part of wire w 2) leads to a second electro-
magnet (em 2); thence the wire w 2 leads to the contact point W EC. A wire (r w)
attached to the stud (st) of the tumbler (tu) is a "return wire" providing for
attachment to the "test" division of the lever-contact, as before-mentioned, or to
any other suitable circuit attachment.
Third. The main sight-signalling circuit is the following (Diagram VII): from
the one division of the starting-signal contact at " danger" (S. s. c., 1), the wire
leads to one pole of battery (b). From the other pole the wire leads to the
automatic index (A 1); thence by wire or earth (n. p. 13) to the other automatic
index (a i), thence by wire wt to the corresponding rail opposite (Cro), along that
rail to the point of crossing by wheel and axle, thence along the rail (R R of Diag. I)
to a point near to i of Diag. VII, within the distant-signal distance; from thence
a wire (p. c. d. 1) is led to the division of the starting-signal whence it started.
The other contact division (S S c., 2) is connected to the rail on the near side of
the departure contact by the wire p. c. d 2.
When the starting-signal is maintained at danger until a train is "departing,"
the indices remain at "blocked": when the starting-signal is lowered before a train
reaches the insulated point i within the distant-signal distance, the indices shew
"clear" on that point of insulation being passed, but the automatic switch
index (A S) will then shew "blocked locally."
RÉSUMÉ OF ACTION OF APPARATUS.
Referring to Diagram VII, (Sheet 6), we describe the mode of operation of the
apparatus as a whole, in the following summary of the modes of action already
described of the various parts:- A train is supposed to be travelling in the direction
pointed out by the arrows. The section of railway to be particularly considered
is that from the end of the departure contact at station Z (d. c.), to the end of the
departure contact at station A (D. c.). If the arrangement of an advanced mid-
distance contact as represented in diagram V, Sheet 4, be in use, the .signalman
at A will have received an intimation, equivalent to "Be ready," when the train
was passing between Y and Z (Diag. V); if not, % will have code-signalled the fact
of approaching train to the signalman at A, who, if the section Z to A (Diaga. VII,
&V) be clear, lowers his distant-signal from danger to clear: this is an intimation
to Z that the train may enter section, and to B (Diag. VII again) that section Z
to A has been "cleared." (The continuous, followed immediately by the single,-
stroke indicates A's signal-movement.) Then, the train having "entered on
section," the following events occur:
"
(1) When the first pair of wheels passes the departure contact at 4, the
"automatic indices at Z and A shew "section blocked." (2) About mid-way
between Z and A, the "mid-distance contact" is passed over, and the sound-signals
at A, Z and B indicate the train's presence on that "contact
indicated as before described and referred to.
23
: speed is also
The train now runs on and passes over the "arrival rail-section of contact"(A.c.),
and in doing so gives indication of its presence there by single-stroke sound to A, Z,
and B. Should A, however, have previously found it necessary (as when a train
crosses from opposite line of rails during shunting, in fog, or otherwise) to switch
on the danger sound-signal, and raise the distant signal to danger," the passing
of the train over the arrival-contact (A. c.) will sound the danger sound-signal,
and, instead of a single-stroke. "clear" sound, it will give a continuous or
66

page_text: 66 danger intimation of its approach to station A to the other stations. As
soon as the train, in the former case of a "clear" line, has passed the distant
signal (D. s.) at A, the signalman would raise that signal to "danger," and this
movement would, (like that mentioned on the previous page, but in reverse order
of sounds), be known to Z and B.
In either case, the train now passes the point of insulation i, and the automatic
switch and local index A. S. shews "blocked locally," as well as ensures (when the
danger sound-signal is switched on) that a following train passing over the "arrival
contact will sound the danger sound signal.
The train has now, we shall suppose, arrived at station A, and is about to depart
therefrom. The starting-signal is lowered, and both automatic indices (A I
and a. i) at A and Z, which have all along remained pointing towards "blocked,"
now shew clear."
66
The departure-contact (D. c.) is then passed over, and, as the
distant-signal is at "danger," a departure-from-A intimation to B and Z is a
"continuous" sound: this over, the local index (A. S) also shews "clear"; and
the events begin to be repeated for another section of the line.
DIRECTION AND EFFECTS OF CURRENTS OF ELECTRICITY IN AND UPON THE
APPARATUS.
(a) Assuming that the space between the danger-division of the lever-contact
and the return-division (Diag. VII D. d. and R. d c) is bridged over by the
distant-signal at A being at "danger"; and that the train above referred to is
passing over the advanced mid-distance contact between Z and Y, (Diag. V) [to
which, as mentioned under heading "Lastly," section "Second," there may be a
wire direct, (m d w., Diag., VII];. and further assuming that the pole of the
battery, b d, next to the letter b, is the negative pole, that next to the letter d being
positive, then, in this instance, the current will pass along the wire to the danger test
sound-signal (t ds) which will ring with a "continuous" stroke, thence the current
passes through wire and across the switch S w Z, to the sound-signal at Z (Z S S)
which rings "continuously " in sympathy with t. d. s.,-thence to earth plate Z E P,
thence by earth to earth plate BE P, thence to sound-signal B. s. s., which also
rings "continuously,"-thence the current passes through wire Bw to D c, and
thence by wire, across switch S w B to the test-division (t. d.) of lever-contact,―
thence it passes to the "speed-indicator" (si), which it actuates as before-described,
and passing along wire m'd w to division 1 of the "advanced mid-distance contact,
the current there crosses by wheel and axle of train to the "corresponding rail
opposite" along which it passes to the return wire (R W Diag. VII), and along
this wire, across the lever-contact, and along wire to the negative pole of the
battery b d, from the positive pole of which it started.
When the distant-signal at A is placed at "clear," the current passes similarly
through the apparatus, with the exception that it flows from, and to, battery_b. c.
ringing the test clear sound-signal t. c. s, and the sound-signals Zss and Bss
with "single" stroke only, and crossing the lever-contact, on its return, by R d. c.
and c. d.
"
"
In every other instance of wheel and axle passing over a "rail-section of con-
tact connected with this ordinary sound-signalling or "speed-indication, the
current crosses by wheel and axle at the given rail-section of contact, and, simply
by "short-circuiting as we may denote it,-performs (wire T W and d t w
Diag. VII, being part of circuit) the remaining sound-signals, e.g. of "arrival" and
"departure" before described and referred to. Thus, with distant-signal A at
"danger" as assumed above, the current, after passing round as above described to
the test-division of the lever-contact, would (for an "arrival" intimation, for
example,) pass along wires T W and d t w, across wheel and axle at A c, to
corresponding rail opposite C r o, and back to battery b d by wire R W, as before
described.
When the test switch (T S) is used, the only difference is that the current
"short circuits" across the switch, instead of pursuing the circuitous routę

page_text: by t. d. and wires m d w, or T W as the case may be, across the line of rails and
back by RW from the corresponding rail opposite.
For the danger sound-signal (DSS), the current passes from the battery D B,
positive pole next to letter B, along wire D bs, and divides by shunt to
ring D. t. s, the test danger sound-sigual, thence it passes by part of switch D. D. S.
and wire SS W to the danger sound-signal, D SS, which it causes to sound;
thence the current passes by wire d. t. w to the "arrival" contact, across wheel and
axle to corresponding rail opposite, and back by wire R W to the danger division of
lever_contact, across this, and thence to opposite pole of the battery by the
wire D d w.
When, however, the automatic switch, A. S., is in action, as before described
and hereinafter referred to, the current will return to D B by wire as w,
across switch A S, thence by wire to switch D D S, and thence by wire Dsw
to the opposite pole of the battery.
If the switch S w Z be turned on to the end of wire leading to earth-1
plates EP, the current will, (instead of going to Z S S), pass to earth-plate s E P,
and thence to earth-plate B E P,-and thence as before described.
If the switch S w B be turned down to the end of wire s. e. P, the current will,
(switch S w Z being in position as in diagram VII) after arriving at Z E P, as
before described, pass from Z E P to s EP along wire s. c. P, across the switch,
and thence to the test-division of lever-contact, thence it will pass, and return, as
above-described.
-
B to the
(6) Taking now the circuits for the automatic indices, and assuming the first
wheels of train to have passed the departure contact at Z (d. c.), also that the
starting-signal at A is placed at " danger," then the current passing from battery b, 2
at station A, will first deflect the index AI from "clear," at which it has been
standing, to "blocked"; the current will then pass along wire o. p.
index a i, which it similarly deflects to "blocked,' thence it passes by wire W t
to the "corresponding rail opposite," whence it crosses (by wheel and axle of some
portion of the train, at whatever point of the line between d. c and D. c. the train 3
is, for the time being, located,) to the rail R R ; and then,-if previous to arrival
at the point i,-it passes by wire p. c. d. 1, to point 1 of the starting-signal
contact (S. S. C. 1), and thence by wire to the opposite pole of battery b. But, if
the train have passed point i, the current will cross from C r o by wheel and
axle to the portion of the rail R R lying between i and D. Goog and thence it will 3
pass to point 2 of the starting-signal contact by wire p. c. d 2, it will then cross this
contact to point 1 (S S C 1), and thence the current will return to battery b by
wire as just stated above.
If, however, the starting-signal have been lowered before train arrival at i, the
current ceases to pass and the indices return to "clear" (i.e., at AI and a i) as 4
soon as the train has passed the point i; for it is obvious that the train has then
left this automatic-index circuit in its first above-described portion.
If the starting-signal be lowered, secondly, before train has passed off the portion
of line between i and D. c., the automatic indices which have been deflected to
"blocked" by the passage of the current as above, until now, will at once shew 4
"clear"-the circuit of the indices has thus been "broken."
When no train is on the section (d. c. to D. c.) of line, and the switch AI W is
closed, the current passes from battery (b), to A I, deflecting this index to "blocked,"
thence by wire op B to index ai which it also deflects to "blocked," and thence
by wire W-t, to the "corresponding rail opposite," along this rail to wire R W con-
nected with the sound-signal circuits; from this wire R W, the current passes by
wire to the switch A I W, then across this switch, and along wire˜p. 1. w.
to the opposite pole of the battery (b).
Finally, when a train is on the line between point i and D. c., the current passes
from battery A B along the wire to the switch and automatic index A S, this 5
index it deflects to "blocked "-it having been previously at "clear"; thence
the current passes by wire to the “ corresponding rail opposite," from which it

page_text: crosses by wheel and axle to rail R R, whence it returns by wire to the opposite
pole of the battery A B.
Having particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
First. The application of electrical apparatus to sound and sight-signalling on
railways and other lines of rail, including the testing of the working-condition of
the same, the whole being constructed and arranged substantially as hereinbefore
described.
Second. The employment,-in electrical signalling on lines of rail,-of portions
of one or both lines of rail, insulated from the remainder of the railway in any
effective manner, and by any, or no, insulating material,-as poles or divisions of
contacts, hereinbefore termed "rail-sections of contact," which rail-sections of
contact may be of any desired length, as herein before described and indicated.
Third. The arrangement in connection with the mechanism of the lever-
contact consisting of "danger," "test," "clear" and "return" divisions, (the
"test
"division not being indispensable to the signal-working), wheel or roller-
contacts with their carriage, and with rod and lever connections to the signal-lever,
substantially as arranged and herein before described.
Fourth. The arrangement acting as the indicator of speed (Diagram VI, and
Diag. VII, s. i.) with its associated "mid-distance" rail contacts at a definite
distance apart, and circuit connections, having a tumbler armature (tu.. a) the
projecting part of which (p. c.) forms a switch which makes contact alternately with
the wire leading to electro-magnets Em 1 and e m. 2 respectively, and having
a friction-wheel (F W) moved, when the electro-magnet Em 1 has acted on the
armature, by a corresponding friction-wheel fixed in any clock or timekeeper,―the
axle of the friction-wheel (FW) moving a pointer on a dial which is graduated to
indicate the speed in miles per hour, and to shew the time occupied by the train
in running the distance between the said contacts, or in running a definite distance,
as one mile,- -as before described.
Fifth. The application of an automatic switch to the working of railway, and
other line, signals, substantially as described above with regard to the automatic
switch (Diag. VII, A S), which closes the circuit for the operation of the electro-
magnet sounding, (by means of a striking attachment), the danger sound-signal
(D. S. S).
Sixth. The arrangement of an automatic index substantially as above-described,
in the sight-signalling of trains, the essential part of whose circuit is its completion
by a train, or portion of a train, or a trolley, or other vehicle, being present on the
section of line, or its loop-lines, or sidings, to which the sight-signal is applied.
Dated this Ninth day of September 1891.
ARCHIBALD DRUMMOND MACDONALD.