AN IMPROVED METHOD OF AND APPARATUS FOR THE TRANSMISSION OF SIGNALS BY ELECTRICITY BETWEEN RAILWAY TRAINS AND STATIONS OR OTHER PARTS OF THE LINE, AND FOR SIMILAR PURPOSES
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by William Robert Lake at the Office of
the Commissioners of Patents on the 14th August 1878. A communication
from abroad by Angelo Cattaneo, of Pavia, Italy, Civil Engineer.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "AN IMPROVED METHOD OF AND APPARATUS
FOR THE TRANSMISSION OF SIGNALS BY ELECTRICITY BETWEEN RAILWAY TRAINS
AND STATIONS OR OTHER PARTS OF THE LINE, AND FOR SIMILAR PURPOSES."
[A communication from abroad by Angelo Cattaneo, of Pavia, Italy, Civil
Engineer.]
The principle on which this Invention is based consists in using the rails upon
which the train travels as an electric conductor, and in insulating the right-hand
wheels of the carriages from the left-hand wheels thereof as an essential and
indispensable condition, as the current has to travel by one rail and return by the
other. This object may be obtained by reason of the great resistance of the soil to
the transmission of the electricity from one rail to the other, and by the weak
tension occurring with regard to the shortness of the circuit and the large section of
the conductors. It is however desirable in practice to coat the outside of the rails,
except the surface thereof, with tar or other cohesive matter; it will be useful also
to lay gravel and small particles of earth between the rails of the double line.
On railways where the rails touch their supports only and not the soil, their
insulation is far superior to that required for the purposes of this Invention.
In carrying the said Invention into practice, the line is divided into sections
comprising the distance between two stations. The rails all along that section are
joined together by means of screwed iron bands, which have been previously tinned
on the side of contact between the band and rail; or in order to avoid tinning they
are united by means of short copper wire of convenient size, slightly curved and
soldered together in holes made at their ends nearest the joints.

page_text: Every locomotive or its tender carries an electric battery of sufficient power, but
of small tension, also electric bells, a commutator, and one or more metallic springs
touched slightly at each side during the journey by the nave of one wheel or more,
right and left. For greater certainty in the movable contact it is desirable to apply
two forked springs in contact with the naves of two wheels at each side, thus
producing at each side four contacts between the springs and wheels, and two
contacts between the wheels and the rail.
It is desirable to solder at the point of contact a brass or copper ring on the
naves reduced to their smallest possible diameter.
A box containing the electric elements should be provided in a convenient place,
varying according to the different kinds of engines.
The electric bells and commutator are also placed in a convenient position, so
that the engine driver may easily hear the former and operate the latter; without
being shut up they must be protected from the weather.
The commutator is composed of four brass knobs or buttons fixed in a piece of
wood or ebonite to the four summits of a square with spherical caps or heads
resting on the surface of the said piece, and provided on the opposite extremities
with holes and adjusting screws. In the centre of the said square there is inserted
a lever composed of insulating material and revolving on an axis, and carrying
underneath two flexible brass plates so as to cause by pressure their extremities to
touch the said four caps. A spring applied to the said axis drives the lever against
a stop, whilst the extremities of the plates touch the caps; another obstructing part
limits the rotation of the lever to one-fourth of a revolution from its automatic and
normal position.
All the wheels on the right-hand side of the carriages must be insulated
electrically from those on the left-hand side.
Among the various means for insulation the following may be mentioned, that is
to say :-
The oxydation of the axle connected with the nave by means of steam super-
heated by the process known as Barff's, together with a coat of varnish of minium ;
also superficial sulphurization by sulphur vapour and an additional coating of
minium.
Another means of insulation applicable to new constructions consists in inserting
wood in the wheels of the carriages. The iron wedges securing the axles on the
wheels must not turn direct on the axle, but on a plate previously introduced. The
positive pole of the battery is connected with the bobbins of the electro-magnet of
the bells, and then with one of the rails, as for example, with the rail on the right-
hand side and the negative pole with the left-hand rail by means of copper wire in
the following manner, namely:-A wire from the positive pole to one of the knobs
or buttons of the bells, another wire from the other knob or button of the bells to
one knob or button of the commutator, a third wire from the negative pole to
another knob or button of the commutator, and a fourth and fifth wire from each
couple of right and left springs respectively to the other knobs or buttons of the
commutator. The plates of the commutator in the automatic position unite the
positive pole with the left-hand rail. By moving the lever one-quarter of a
revolution, the connection of the poles with the rails is reversed.,
The engine driver, before giving the starting signal at each station, by moving a
lever, puts two wheels which are in contact with the springs into electrical com-
munication, to make sure that the battery and the immediate contacts, including
the wheels, are in perfect order, and thus closing an immediate circuit and hearing
the signal indicating the proper state of his electric apparatus, he whistles and
starts.
When a train arrives at a section without the automatic alarm taking place, it is
evident that the rails do not communicate one with the other at any point of the
section, or that the section itself is clear. If another train should be already
travelling on the section in an opposite direction, the action of the poles of its

page_text: battery on the rails being naturally reversed with respect to the action of the
battery of the other train, it follows that the circuit is closed, the current traverses
the batteries of the two trains, and the simultaneous signal takes place.
By working in proper time the lever of the commutator so as to apply it as a
keyboard, the circuit is alternately broken and re-established, and signals and
messages may be exchanged.
When a train travels at a slackened speed, or if through an accident it is
compelled to stop, the driver is enabled to protect his own train and other trains
that might be running against or after him, by operating the commutator now
and then.
In addition to the bells a telegraphic instrument may be applied for exchanging
messages.
Station masters are enabled to signal with running trains by putting the two
rails into electrical cominunication. For this purpose four underground wires are
soldered one to each rail of the section right and left of the station end, at the
station, on four brass knobs fixed in the summit of a square; by means of two brass
plates the desired connection with one or the other of the above sections or with
both is established.
In case of a train not stopping at the station, a few minutes before its arrival,
the plates turn so as to remove the interruption in the rails by forming a single
section of the two (right and left), thus preventing the possibility of a collision at the
station.
The watchmen or signalmen on the line also can communicate with the running
train by means of two wires applied to the rails and worked by a keyboard.
For the purpose of receiving messages from the trains, two bells are put in
circuit at each station, one for the right-hand section, and the other for the left-
band section. Bells are also put in circuit in every signal box or house.
In adding to the four fixed knobs or buttons at the station two other knobs, a
compass may be inserted in the circuit for each section for the purposes of indicating
by the deviation of the needle the presence and direction of a train. However,
as the train itself must not be disturbed unnecessarily, the closing of the circuit
must be effected by means resisting electric transmission so as to allow only a weak
current capable of producing the deviation of some degrees in the compass, but
quite powerless to operate the bells. Two thin metallic plates, kept asunder at a
distance of a few millemetres and immersed in a vessel containing water and
constituting a kind of rheostat of great simplicity, answers all purposes.
The connection of the wires is effected as follows, that is to say--A wire extends
from a knob or button suitably placed to one of the knobs or buttons of the
compass; another wire extends from the other knob or button of the compass to
one of the thin metallic plates, a third wire from another knob or button to the
other thin metallic plate.
In one position of a revolving plate the closing of the circuit is effected imperfectly,
that is to say, with a great resistance owing to the film of water between the two
thin metallic plates, and when a train runs on the corresponding line the needle of
the galvanometer deviates. On the other hand, by bringing the plate to another
position the metallic closing of the circuit is effected, and in case of the presence of
a train its own bells as well as the corresponding bells at the station are put into
operation.
The same process applies to the other section.
As the aqueous closing of the circuit can be maintained without inconvenience,
the guard of the train himself can initiate communications with the stations by
causing the needle to oscillate by means of the alternate movement of his.
commutator.
By applying the electrodes of a local battery to the 2 knobs corresponding to
the rails of a section, the station masters can always mutually ascertain not only
whether the electric current is continuous, but also whether the line is clear. The.

page_text: interruption of the two rails, and also of the opposite rails, can be effected by a rail
on the right hand of the station; for the other, by a rail on the left hand.
When it is desired to make the apparatus intended for preventing collisions at the
stations self-acting, two complementary rails are applied, each about four hundred
metres long, and connected at their ends by means of wire with the ordinary rails.
These complementary rails on the passage of a train are slightly pressed by the flange
of the wheels in contact with springs in connection with the electric apparatus, on
which flange it will be advisable to solder a copper ring, or I may employ the
following easy and inexpensive means for superseding these complementary rails,
that is to say I provide a cylinder connected with a clock at the station so as to
complete a revolution in twenty-four hours, graduated in ten minutes on one of
the plane faces of the periphery, carries as many appended pieces as there are
direct trains passing during the day, in a position corresponding to the time of
passage of the trains.
These pieces consist of two small brass plates placed side by side in a plane
passing through the axis of the cylinder, insulated from each other and secured on
a fixed small vice which is fastened with adjusting screws on the proper degree of
the cylinder.
Five minutes before the passage of the train each of the two plates meets the
extremity of two small brass springs soldered to the wire connected with the rails.
This contact would remove the interruption of the rails, and would form a single
section of the two right and left of the station, during the whole time of
contact.
At the bifurcation of the double line the apparatus indicates to the driver
whether the switch is in the right position. For that purpose, at a distance of
400 metres before the switch, there are placed in the two branches of the siding
two advising rails, preferably of copper or tinned iron, each about 10 metres long, and
connected respectively by means of underground wires with two sections of the
switch. These sections have no electric connection between themselves nor with
the point when the two rails cross. The said point is not connected with the rails ;
a wire connects one rail with one section of the switch, and the other rail with the
other section. The rails must be insulated from the plates on which the switches
rest and slide.
In order to make certain of the electric contact between the moveable points
and the rails it will be advisable to apply tinning or to solder on small copper
plates.
If a train runs from the single line towards the siding rail, the mere fact that the
points are touched sooner on one side than the other produces no signal; however,
all the other signals can be given all along the open line. If, on the other hand,
the train runs from one of the branches of the siding towards the single line by
passing over the advising rail, the bells operate or do not operate, according to
whether the switch is missed or not, whereby, in the first case but not in the
second, the closing of the circuit is ascertained.
If two trains, should run from the branches of the siding towards the switch no
collision can happen, since the train which finds the line blocked is advised thereof.
In case the branches of the siding should end at two stations at a short distance
from the switch the advising rails become unnecessary, since the rails themselves.
serve this purpose.
On an alarm being given the driver knows at once whether it refers to another
train on the line; in that case the signal takes place only by one of the two
opposite positions of the commutator. In all other cases the alarm is given by both
positions.
The mere failing of the mutual insulation of the wheels would not constitute a
danger, but simply occasion a false alarm, easily ascertained by the commutator.
A false alarm might also be raised by an excess of electric deviation produced by
an eventual but improbable inundation of the double line, but it could be easily

page_text: detected through the relative weakness of the current, the absence of the con-
ventional signals, and the play of the bells in the two positions of the commutator;
however, this would not prove a danger.
Other applications of the principles of this Invention besides those above described
may be made, such for instance as obtaining automatic signals of the giving way
of bridges, tunnels, adjacent rocks, or the like.