IMPROVEMENTS IN INTERLOCKING ELECTRIC AND OTHER SIGNALLING APPARATUS FOR RAILWAY AND OTHER TRAFFIC, PARTICULARLY APPLICABLE TO EXISTING FORMS OF ELECTRIC RAILWAY SIGNALLING APPARATUS
Year: 1882

page_text: LETTERS PATENT to William Edward Langdon, of 5, Grove Terrace, Derby,
in the County of Derby, Superintendant of the Midland Railway Telegraph
Department, for Invention of "IMPROVEMENTS IN INTERLOCKING ELECTRIC
AND OTHER SIGNALLING APPARATUS FOR RAILWAY AND OTHER TRAFFIC,
PARTICULARLY APPLICABLE TO EXISTING FORMS OF ELECTRIC RAILWAY
SIGNALLING APPARATUS."
་
PROVISIONAL SPECIFICATION left by the said William Edward Langdon
at the Office of the Commissioners of Patents on the 11th February 1882.
WILLIAM EDWARD LANGDON of 5 Grove Terrace Derby in the County of Derby
Superintendant of the Midland Railway Telegraph Department. "IMPROVEMENTS
IN INTERLOCKING ELECTRIC AND OTHER SIGNALLING APPARATUS FOR RAILWAY
AND OTHER TRAFFIC PARTICULARLY APPLICABLE TO EXISTING FORMS OF ELECTRIC
RAILWAY SIGNALLING APPARATUS."
The object of this Invention is to provide an improved means of interlocking
the electric and outdoor signals governing the traffic of railways and tramways so
that especially
First. It shall not be possible to place a starting or standard signal governing
the departure of a given train or engine in the "all clear" position until the
electric signal for such train has been placed in the "all clear" position.
Second. It shall not be possible to release an electric "line blocked" signal until
the train for which the signal was set at “lino blocked" has passed out of the
section.
Third. It shall not be possible to release the block signal for, or to give the
"all clear" signal to the section out of which the train has passed until it has been
signalled forward to the next section in advance, and until the "line blocked"
signal for that section has been received.
And I perform this in part or whole as may be desired.
Although the apparatus and arrangement herein referred to has been designed
chiefly in regard to its application to the existing forms of needle block signals,
and in describing it that form of instrument is referred to, it is to be understood
that it is equally applicable to all other forms of electric block signals.
With the single needle form of block the needle is at times employed to indicate,
by transitory or momentary movements to either side various signals whilst the
TDi 10.11

page_text: "
"
more permanent, or for the time being, fixed position or indication of the needle is
employed to indicate the signals "line blocked" and "line clear With this form
of instrument I make use of the last action required to complete the "line blocked
signal viz: the insertion of the blocking pin in the handle or barrel of the
instrument by which the needle is pegged over to "line blocked." And in other
forms of instruments where the block and clear signals are rendered by one action
of the key, plunger, switch or other form of commutator I employ that action which
produces the current for rendering or for itself producing the block signal, to bring
into operation the locking arrangement by which the block position or signal is
maintained upon the instrument and upon the signal lever during the time the train
or engine is in the section governed by it.
To this end I apply (a) to the commutator portion of the electric block
instrument, a locking arrangement by preference mechanical and (b) an electrical
releasing arrangement. In connection with the permanent way metals or route of
the train I place (c) a commutator actuated by the train, and in connection with
the signal lever or levers governing the outdoor signals controlling the road under
block a catch arrangement (d) controlling or stopping the movement of such lever
or levers. And (e) in order to better ensure a duc performance of the signals,
and facing points 1 apply to the signal where such is required an automatic ignitor
which by means of electrical appliance is brought into action when the light is
extinguished, and (f) to the facing points an improved electrical contact and circuit
arrangement to indicate the position of the points.
Now in illustration of the system herein proposed; let it be assumed that
A. B. C. represent three signal stations and that a train has to proceed from
A to C.
-lt-is-necessary-for-A-before-be-can-move his starting station or other governing
lever to signal to B the "be ready" signal, when if B is prepared to admit the
train into the section between A and B, he will place his electrical signal for that
section at "all clear" by which means the electrical locking arrangement in
connection with the lever which controls the train standing at A will bo
released.
The signal being lowered the train will proceed, and its departure will be
announced to B in the usual manner B will then replace the "all clear" signal by
"the line blocked" signal and in doing so will lock the electric block commutator
at B governing the road from A to B in the blocked position in which condition it
will be retained until the train arrives at B and operates the commutator placed in
'connection with the route of the train.
On
After having blocked A, B will send forward the "be ready" signal to C, and C
will release the governing lever at B in the same manner as did B that at A.
B will now be in a position to pass the train on, and will in due course do so.
the train passing over the electric commutator placed in connection with the route
of the train it will operate the same and a current will pass through and discharge
the catch piece beld by the train releasing an electro magnet placed in B's block
instrument working to A. This instrument is provided with a second electro
magnet and catch piece termed the "block releasing electro magnet." The first
named catch piece on being discharged by the passing of the train is moved but
does not release the lock on the barrel of the block instrument. But on the train
being signalled forward by B to C, and on C rendering to B the block signal for
the same a current is sent from C through the "block releasing electro magnet'
which discharges the catch piece engaged therewith which (the other catch piece
having already been discharged) now carries with it the locking bar of the electric
block instrument, leaving it free of movement. B is thus enabled to release the
block signal up to this movement in operation between B and A.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Edward Langdon in the Great Seal Patent Office on the
11th August 1882.
WILLIAM EDWARD LANGDON of 5 Grove Terrace Derby in the County of Derby
Superintendent of the Midland Railway Telegraph Department.
"IMPROVEMENTS
IN INTERLOCKING ELECTRIC AND OTHER SIGNALLING APPARATUS FOR RAILWAY
AND OTHER TRAFFIC PARTICULARLY APPLICABLE TO EXISTING FORMS OF ELECTRIC
RAILWAY SIGNALLING APPARATUS."
This object of this Invention is to provide an improved means of interlocking
the electric and outdoor signals governing the traffic of railways and tramways 80
that especially,
I. It shall not be possible to place a starting or standard signal governing the
departure of a given train or engine in the "all cloar" position until the electric
signal for such train has been placed in the "all clear" position.
II. It shall not be possible to release an electric "line blocked" signal until
the train for which the signal was set at "line blocked" has passed out of the
section.
III. It shall not be possible to release the block signal for or to give the "all
clear" signal to the soction out of which the train has passed until it has been
signalled forward to the next section in advance and until the "line blocked"
signal for that section has been received.
And I perform this in part or whole as may be desired.
Although the apparatus and arrangement herein referred to has been designed
chiefly in regard to its application to the existing forms of needle blocked signals
and in describing it that form of instrument is referred to it is to be understood
that it is equally applicable to all other forms of electric clock signals.
With the single needle form of block the needle is at times employed to indicate
by transitory or momentary movements to either side various signals whilst tho
more permanent or, for the time being, fixed position or indication of the needle
is employed to indicate the signals "line blocked " and " line clear." With this
form of instrument I make use of the last action required to complete the "line
blocked" signal viz-the insertion of the blocking pin in the handle or barrel of.
the instrument by which the needle is pegged over to "line blocked." And in
other forms of instruments where the block and clear signals are rendered by one
action of the key plunger switch or other form of commutator I employ that action
which produces the current for rendering or for itself producing the block signal,
to bring into operation the locking arrangement by which the block position or
signal is maintained upon the instrument and upon the signal lever during the
time the train or engine is in the section governed by it.
To this end I apply (a) to the commutator portion of the electric block instrument
a locking arrangement by preference mechanical and (b) an electrical releasing
arrangement. In connection with the permanent way metals or route of the train
I place (c) a commutator actuated by the train and in connection with the signal
lever or levers governing the out-door signals controlling the road under block
catch arrangement (d) controlling or stopping the movement of such lever or
levers and (e) in order to better ensure a due performance of the signals and facing
points I apply to the signal where such is required an automatic ignitor which by
means of electrical appliance is brought into action when the light is extinguished
and (f) to the facing points an improved electrical contact and circuit arrangement
to indicate the position of the points.

page_text: In the accompanying Drawings I have shewn the manner in which this my
Invention is or may be carried into effect I will first describe the block
instrument.
Figure 1 is an outward representation of the form of block instrument known
as the single needle block. Figure 2 is a vertical transverse section on line a a
Figure 4; Figure 3 is a vertical transverse section on line b b Figure 4 the latter
Figure is a vertical longitudinal section on line cc, Figure 2; Figure 4ª is a plan
section on line d d.
A is the handle by which it is worked and which is on a spindle A' a is the
magnetic needle working in consonance with the handle A and affording the
required indications on the dial a'. When the handle A is carried over to
the position indicated by the dotted outline B the indicator a² assumes that shown
on the dial a¹ by the dotted line band when the handle A is carried over to the
When it is
position C the indicator assumes that shown by the dotted line c.
required to retain the handle A and consequently the indicator a in either of these
positions the pin D is passed through the hole across through the spindle or
barrel A' of the handle and resting against the usual stop lug at 1 in such a
manner as to retain the handle in the position placed.
Surrounding the lower portion of that part of the barrel or spindle A¹ outside
the instrument case is a mictal case E enclosing two small levers f and g. When
the handle A is held over in the dotted position B and the block pin D is placed
in the block hole of the barrel in the direction of the line f¹ the end of the pin
will press upon and operate the lever f and when the handle A is placed in the
opposite position and the pin D inserted in the direction of the line g¹ it will
operate the lever g in a similar manner.
FFigures 3-and-4-is-a-spiral-cam-centred_at_h_and connected by crank rods i i
to the rod g* upon which the small lever g is fixed so that when gis pressed downtis
carried forward in the direction of the arrow until it reaches the extreme limit of
its movement. At this point a spring / bears upon a flat surface or cam / formed
on the axle upon which the spiral cam F is fixed and carries the connection i over
the centre leaving the spiral spring on the withdrawal of the blocking pin D
(Figure 1) to complete the revolution and restore the spiral cam to its normal
position.
l
Upon a base plate G fixed to the back board of the instrument are mounted two
electro magnets (formed of either a single coil or a pair of coils each) m termed the
train releasing electro magnets and m' termned the block releasing electromagnet.
These coils each act independently the one of the other. Pivoted at n and n are
two catch pieces H H¹ and pivoted in the same field is a locking piece I which is
connected with the catch pieces H H by pins oo'. These pins o o¹ are fixtures on
the catch pieces H H but work in a slot in the locking bar I as shown in Figure 4
so that the one pin o or o' has a certain initial movement independent of the other
when either the locking bar I or the catch picces H H' are set in motion. Above
the electro magnets are armatures p p¹ which are held in the horizontal position
shown by being fixed upon springs p* each armature is provided with a hook or
catch piece at the outer end see Figure 4 so that when H Hare raised to the dotted
position they engage with and are held by the said hooks on 2 p'.
Fixed on the barrel A' of the instrument upon which is fixed the handle A
(Figures 1 and 4) is an engaging or locking bar K which moves with the
bandle A.
If now the handle A (Figures 1 and 4) be placed in the position C and tho
pin D (Figure 1) be inserted the lever g is pressed down and the spiral cam F by
means of the levers and rods i³ and connected to the spindle g* of the
lever and thus carried round and in thus revolving raises by means of its
extended or larger part the locking piece I. The locking piece I carries with it
the catch pieces HH' lifting them into that position which enables them with
their hooked upper ends to engage with the hook or catch pieces on the arma-
tures p, p', by which they are held. At the same time the largest part or nose of

page_text: he spiral cam F passes free of the locking piece I which has now been raised to
he dotted position shewn in Figure 4. In this position the locking piece I engages
with the locking bar K and the handle A becomes locked in the "line blocked
position the needle A pointing to the same position.
The electro magnets m m¹ are actuated electrically from different points, m is
n circuit with a contact maker in connection with the metals and m' is in circuit
with the instrument at the signal post next in advance. The armatures Pp will
each be attracted to the cores of the electro magnets on a current being passed
through their respective coils and thus when the train passes that point at which
the contact maker in connection with m is placed, the arinature p will be attracted
and the catch piece H discharged. This will not however release the locking
piece I as it is still upheld by the catch picco H' which is still retained in the
dotted position (Figure 3) by the armature p'.
The instrument at the station in advance is provided_with a spring k (Figures 2
and 3) which ordinarily rests upon the nave of the cam F and when in this position
its outer or free end is free from from the contact stud r above it. On that station
transmitting to the station in the rear the block signal for a given train the cam F
will be revolved as already explained and in the course of this revolution the flat
or small cam k on the nave of the cam F which also serves as previously explained
to carry
the cam F over its centre will force the spring & into contact with the
aforesaid contact stud r and so transmit a current through the coil m¹ when upon
its armature p being attracted the catch piece H' will be released and the locking
piece I being no longer supported will fall away from the locking bar K and the
handlo A will be again free to move. Thus the handle A having first been placed
to the "line blocked" position and pegged there, the instrument becomes locked in
that position until the commutator in connection with the metals is actuated by the
passing train and until the train has been signalled into the advanced station and
the instrument for that section has been placed at "blocked."
In Figure 1 a small lever fis represented to the left of the axle of the handle A.
On the fulcrum spindle fof the lever fa cranked lever s (Figure 2) is fixed
which moves in consonance with the lever f. In its normal condition the contact
levers is in contact with the plate t Figure 2 but when levers fand 8 are caused
to be raised then 8 forms contact with the plate t¹. The plate t is connected with
the battery power required to work the block needle only. The plate t' is connected
to a battery of larger power. Thus when the pin D pegs the handle A over to the
line clear"
or B position, Figure 1, an increased battery power sufficient to work
the needle instrument and the signal lever locking instrument at the station in the
rear is brought into circuit whilst at other times the normal or minor battery
power only is in use.
"
L (Figure 4) is a key of a private lock provided for the use of station agents or
others in authority in case occasion may arise for releasing the lock upon tho
instrument. On turning the key an eccentric u depresses the lover which in its
turn depresses the armatures ? p' so that they are unable to retain the catch
nicces H H'.
Figure 5 is a side view partly in section, Figure 6 a transverse vertical section
and Figure 7 a part plan section.
I employ an instrument with catch piece in connection with a signal lever similar
to that described in Patent Specification No. 1268, 1870 (Preece and Langdon) and
where it is inconvenient to fix this instrument immediately behind the lever, I
extend the action of the lever by connecting rods to any given point at which it is
more convenient to place it. Thus as shewn at Figure 5 I extend the action of
This catch lever wat its upper
the lever M by the rod M' to the catch lever w
end plays through a plate x having a slot in a boss on its underside; on the plate a

page_text: is mounted an electro magnet 2. Z' is a lever turning on a fulcrum Z. and in one
with an armature Z³ from this lever is suspended a small steel rod บ. When a
current of electricity passes through the electro magnet the rod y is raised up free
of the slot but at all other times it lies across the slot in such a manner as to
prevent the catch piece w being drawn over in the direction of the dotted line w¹
thereby preventing the signal lever M from being drawn over from the danger
position.
The electro magnet 2 is placed in circuit with the block instrument applicable
to the section into which the train is about to proceed and when the needle is
pinned over to the "all clear" position the increase of current spoken of in a
previous paragraph caused by the movement of the small lever f Figure 1 actuates
the electro magnets so as to lift the rod y as already explained out of the slot in
which the catch piece or locking bar w works, but at all other times except that
during which the handle A (Figure 1) is pegged over to the "line clear" position
the small stop piece at the bottom end of the rod y prevents the withdrawal of the
locking bar w.
At the end of the quadrant a slot in which the line signal lever M works, or at
other convenient point embraced within the movement of the lever or rods in
connection therewith.-I fix a contact maker (Figure 7) which is actuated by the
lever M when in either the "on" or the "off" position. I employ this where
necessary in conjunction with the lever locking instrument already described to
interlock one lever with another, but in the present instance more particularly to
prevent the signalman giving the "All clear" signal to the station in the rear for
a train which has passed out of section until he has again restored his standard,
starting, station or other signal lever for such train to the "danger" position.
This-I-effect-by-carrying a wire.ca Figure 7 from that pole of the battery employed
to send the current producing the "all clear" signal to a stud ce so arranged that
a spring cn shall rest upon or against it which spring cn is connected unto the
earth. When the signal lever M is in the danger position, marked ON, it carries
this spring cn away from the earth connection, but when M is not in that position
the said pole of the battery is to earth rendering it impossible to transmit anything
but a line blocked indication.
I shall next proceed to describe the automatic contact maker. Figure 8 is an
end view and Figure 9 a side view of this part of my Invention.
O (Figure 8) is a transverse section of the permanent way metal. P is a bent
lover centered at 1 and rigidly fixed by a key or screw to the lower portion of the
metal O so that whatever movement of the metal takes place a corresponding
movement in the lever P ensues. Q is a sliding frame movement upon the uprights
2 2¹ but restricted in its action by side springs 3, 3, 31, 3', so as to require some
force to move it from the position in which last placed. 4, 5 are contact springs
the one insulated the other not necessarily so placed towards the upper portion of
an orifice cut in the plate Q and carrying wires which connect with the battery
and with the electro magnet m (Figure 2); 6 is a screw the object of which is to
regulate the space of action allowed to the lever p between it and the springs 4. 5.
On the rail O becoming depressed the opposite end of the lever P will be raised
and should the plate Q be not of the required elevation the lever P will first press
upon the springs 4 and 5 placing them in contact and then upon the upper portion
of the orifice cut in Q lifting it upwards until the required elevation has been
obtained. On the cessation of the depression of the rail O, the opposite end of
the lever P will return to its position of rest as connected with the rail O, again 5
carrying with it if necessary by its pressure upon the bolt G the plate and will
remain in this position free from the contact springs 4, 5.
Should the rail O from the packing of the sleepers or other causes, become
elevated instead of depressed it is clear it would repeat this action depressing the
plate until it had again become adjusted to the level of the permanent way 5
metals.
Whenever the contact springs 4 and 5 are brought together they complete an

page_text: electrical circuit of which the electro magnet m Figure 2 forms part, and thus by
sending a current through such electro magnet discharge the catch piece H held by
its armature.
Where, from the space occupied by the form of contact maker described in the
preceding paragraph or from other reasons it may be found desirable, I place
beneath the permanent way metal a contact maker, Figures 10, 11 and 12 formed
of a soft (vulcanite) india rubber washer 7, placed first between two washers of
hard rubber 8, and finally this combination between two metal or ebonite plates 13
and 14 the combination of hard and soft rubber being necessary to anneal the parts
together, so as to rendor the enclosed space water tight. Within the space formed
by the washer as seen in the plan view Figure 10 and the longitudinal cross
section Figure 11 I plant two springs 9 and 10 Figure 11 one being insulated to
which are attached the wires leading to the train releasing electro magnet m
Figure 2. Between the contact maker thus described and the rail 12, (Figure 12)
I place an adjusting screw 11, for the purpose of regulating the pressure or space
between the rail 12 and the foundation upon which the contact maker is placed.
On the train passing over the metal 12, it will deflect the same bringing the
springs 9, 10. together thereby completing the circuit of the electro magnet m
Figure 6.
Having now explained in detail the several parts I will proceed to explain the
action with reference to Figure 13 which is a diagram. Let it be assumed that A,
B, and C represent three signal stations and that a train is about to start from A
to C and beyond, and that block posts are established at A. B. & C &c.
At A the starting point there will be provided an ordinary block instrument, and
in circuit therewith the lever electric locking instrument. These two instruments
will be worked from B.
At B will be provided a block instrument fitted with my special locking arrange-
ment explained herein, communicating with the block instrument at A. Also an
ordinary block instrument with lever locking instrument worked from C.
At C will be fixed apparatus similar to that described for B, but for the purpose
of explanation it will be necessary to refer to only a portion of that apparatus.
On the train being about to start from A the "be ready" signal will be sent
forward to station B; station B will then peg over the handle A of his instrument
to "line clear" and in doing so will actuate the small lever f carrying the lever s
so as to bring the latter in contact with the stud t¹, thus the current of the whole
battery series will be transmitted through the instrument at station A and through
the lever locking instrument fixed at that station in connection with the lever
working the line signal governing the departure of the train. This current will
carry the block needle at station A over to "line clear" and will at the same time
lift the steel bar y clear of the slot at the bottom of the frame x so that the catch-
piece w can be drawn over to the dotted position. The signal being lowered and
the train started the "train departure" signal will be sent by station A to station B.
Station B will now reverse the handle A of his block instrument working to
station A and in pegging it over to "line blocked" will bring into operation a
small battery current insufficient to operate the lever locking instrument but at
the same time sufficiently powerful to give the required "line blocked" indication
on the block instrument at station A. The electric locking instrument will thus
be set free and the steel bar y will again interpose so as to prevent the withdrawal
of 2.
Station B in pegging his bandle A over to "line blocked
has actuated the
small lever g causing the spiral cam F to revolve lifting the locking bar K into
position so as to engage with the locking piece I. This latter now remains locked
with K and the block signal cannot be removed.
On the train passing over the commutator in connection with the permanent
way metal at station B the depression of the rail will actuate the commutator so
as to complete the circuit by means of the two springs 4 and 5 Figure 9 or the
springs 9 and 10 Figure 11. A current will flow through the electro-maguet m

page_text: Figure 2 and the catch piece H will be released. At the same time station B
having obtained permission for the train to proceed towards C in the same manner
as has station A from station B, will signal to station C its departure. Station C
in giving the block signal to station B will, as already shown, actuate the spiral
cam F, which in the course of its rovolution will carry the spring k Figure 2 in
contact with the stud r thereby passing a current from the battery in connection
with the latter to station B through the electro-magnet m¹ to earth. This current
will discharge the catch piece H₁ and the locking bark being no longer supported
by either catch piece will, by gravity, fall from its engagement with I and station B
will thus (provided the signal lever governing the train in question has again been
restored to the danger position) be at liberty to signal back to station A the "all
clear" signal for the train passed out of the section. But should station B have
neglected to restore the signal lever M in question to the danger position the
battery current affording the "all clear" signal on the block instrument will be
cut off, and remain cut off so long as the lever is otherwise placed than at
danger" and consequently the section will continue blocked-On the return
of the signal lever to the danger position it will again become locked by the
electric locking instrument remaining so till released after the train has passed out
of the section B. C.
66
-
"
"
This part is illustrated by Figures 14, 15, 16, 17 and 18. These arrangements
are adjuncts to the foregoing. I employ for the purpose of ascertaining whether
-the points-of-crossings-are-in-their-proper-positions,-an-electrical indicator instru-
mont of an ordinary description, capable of two movements, the one movement
producing the word "open "at an aperture in the face of the instrument as shown
at Figure 15; and the other the word "shut or inscriptions to that effect,
indicating with the inscription on the face of the instrument, the position of certain
points as for instance "No. 3 points open or "No. 3 points closed."
And to operate these two indications I make use of a commutator of a novel
description having a double action the combined actions being necessary to the
production of either indication. This double commutator I show in plan at
Figure 14 where A represents a rectangular box in which are placed two tongues,
or contact pieces 6 and 6' centred respectively at c and c¹ the inovements of these
tongues or levers are limited by the contact studs d, d' and d³, d³. To each of
these contact levers I attach a rod B B' insulated therefrom and each of which is
in connection with its point, the position of which is required to be recorded and
which is more fully represented in Figure 15.
Now on the points being opened for the main road the contact levers b, b¹ will
form circuit with the studs d¹ and ³ and a battery current from the battery D will
flow through the contact stud d³ the contact lever 6¹ the connecting wire e the
contact lever b, to the stud whence it will pass to earth, the opposite pole
completing the signal through the instrument and producing the signal "No. 3
points open."
In like manner when the points are shut against the main line, the action will
be reversed, the contact levers b and b will be as represented in Figure 14 and the
battery current from C will now be brought into operation, following the course
of the stud d the contact lever b the connecting wire e the contact lever b¹ and by
the stud to earth; the opposite pole of the battery completing the circuit
through the instrument rendering the signal "No. 3 points shut."
Should the points not be in their proper position, the contact levers 6 b¹ will
fail to reach the contact studs dddd and the shield carrying the words
open ""shut" will remain suspended midway, neither word being visible at the
aperture.
ES
Should either point fail that is the one point not acting with the other, a

page_text: similar result would be obtained, for although the contact lever b¹ may make
contact with the contact studs in relation to it, yet, unless the contact lever b
also makes contact with the corresponding studs in relation to it the result will
be that no current will pass, and the indication will remain neither "open" or
"shut."
In relation to the line signals I make use of a novel arrangement for restoring
the light where it has been put out, or for lighting it when so required, on
emergency, or otherwisc.
Figure 16 is a representation of an ordinary gas burner A; affixed to it is an
insulating substance B and attached to this is a bent wire C with platinum point c¹.
Where the point c' is brought near enough to the burner A and the two wires A¹ C
are placed in circuit with the secondary coil of an induction coil, in action, a spark
will pass from c¹ to A. If this spark passes across the gas flowing from the burner
it will ignite it.
In Figure 17 I represent an ordinary petroleum or oil lamp D. On one side of
the slit or orifice at which the wick or flame passos forth from the lamp. I mount
a pillar C insulated at B and opposite to it I mount a similar but not necessarily
insulated pillar A. If now a current of a sufficiently intense character be passed
through the wick between the two points a' c¹ the wick will be ignited. I obtain
this current by connecting the pillars AC in circuit with a secondary'coil as
above.
For the automatic lighting or relighting of such signals I make use of an
ordinary pyrometer E Figuro 18 placed within the lamps so arranged that when
the heat of the flame reaches it E shall expand and so influence the lever das to
cause it to break contact with the stud e. Thus when the light is burning the
lever & will not form contact with e, but at other times and e will be connected.
If the lamp is provided with gas I fit the burner as shown in Figure 16. If it
is provided with oil lamp I fit it as shown in Figure 17 and if so provided that in
failure of gas an oil lamp may be substituted for the gas I provide for both by
adding such automatic switch arrangement as is required for switching the current
from the one ignitor to the other.
Figure 18 is a symbolical representation of the entire arrangement. E is the
pyrometer, and D the oil lamp within the lamp. F an ordinary induction coil
G, a relay in circuit with the indicating instrument H placed in the signal box or
elsewhere, and K the battery with one pole to the instrument and the other to
earth. At h in the instrument H, is a switch which when placed in the position
(ON) places the battery in circuit and when placed (2 turns it out of circuit.
The instrument H is capable of affording two indications viz, "light in" and "light
out," one indication being produced by gravity the other by the influence of the
current.
Now in illustration let it be assumed that the light of D is out and that the
switch his turned to ON; a current now flows through the instrument producing
the indication "light out," along the line wire L through the relay coils G to tho
stud e and contact lever d of pyrometer whence it will pass to earth. In passing
through the relay coils G the armature 7 will become attracted to the coils and
will form contact with the stud g¹. On the armature g being brought into contact
with the stud g' the local circuit M M with its local battery M will be completed.
A current will flow from the battery M through g g', M, the contact stud f
armature and the primary wire of the induction coil F. An induced current
will be created in the secondary coil F which will flow by the wires C'A' to the
pillars AC and a spark will pass across between the points in connection there.
with so long as the armature f vibrates, thereby making and breaking circuit with
the contact stud f¹.
On the pyrometer becoming influenced by the heat set up by the flame ignited
by the spark, it will expand and will break the connection between & and C, when
the circuit with the instrument H will be broken and as the current from the

page_text: battery K will cease to influence G, the armature g will fall into its normal position
apart from g'. The local circuit M M will by this become broken and induction
ceasing in the secondary wire A' C¹ no sparks will pass between A and C and the
battery M will remain at rest till again called into action by the pyrometer and
switch h.
And having thus described and ascertained the nature of this Invention and
the manner in which the same is or may be carried into effect I declare that I
claim.
First. The arrangement and combination of parts by which the electrical block
instrument which becomes locked on the rendering of the "line blocked" signal
until the train for which such signal has been given has passed out of the section,
substantially as described with reference to Figures 1, 2, 3, 4 and 4ª.
Second. The solf adjusting automatic contact maker substantially as and for
the purpose described with reference to Figures 8 and 9.
Third. The adjusting screw and compressible contact maker formed of ebonite
and india rubber substantially as and for the purposo described with reference to
Figures 10 to 12.
Fourth: The combination of parts forming the contact arrangement in connection
with the points substantially as described with reference to Figure 14.
Fifth Tho combination of parts forming the automatic ignitor substantially as
described with reference to Figures 15 to 18.
Sixth-The combination of apparatus or appliances constituting my improved
interlocking electric and other signalling system substantially as described and
shown.
In witness whereof I the said William Edward Langdon have hereunto set
my hand and seal this Ninth dev af August in the weak of our-Ford-One-