ELECTRIC RELAYS
Year: 1885

page_text: I, JAMES ENRIGHT Electricean of 202 Holland Road Kensington W. do hereby
declare the nature of my invention for ELECTRIC RELAYS to be as follows:―
My invention has for its object improvements in the methods of completing,
breaking and reversing currents.
In many cases where it is necessary to establish electrical contacts by move-
ments, mechanical or otherwise, it is very desirable that the energy used in making
the contacts should be reduced to a minimum. To effect this is the object of my
invention.
For this purpose I bring the terminals of the circuit it is required to establish
into mercury cups and then arrange that a piece of wire shall have its ends
plunged into the mercury so as to bridge over the gap in the circuit. A relay on
this principle may be worked by very small currents.
Take a delicate reflecting galvanometer. The magnet is suspended by a fibre.
A delicate aluminium wire is attached to the wire and hangs vertically. Its lower
end dips into a pool of mercury. At some distance from the lower end of this wire
a branch is fixed at right angles to it. This branch is then bent downwards at
right angles to itself. There is thus formed a rectangle wanting the lower side.
When the magnet is at rest the plane of this rectangle is in the magnetic meridian.
When the magnet is deflected by a small current the free end of the branch traces
out an arc of a circle. At a suitable position in this arc a second pool of mercury
is made. The terminals of the circuit to be completed dip permanently into these
mercury cups. When a deflection takes place under these conditions the circuit
will be completed through the aluminium wire.
I convert it into a reversing relay as follows:-Two light pieces of wire of the
same metal are fixed by insulating material at their middle points at a suitable
angle. Their ends are then bent downwards and the framework so formed is fixed
at its centre to the lower end of the vertical aluminium wire. Five pools of
mercury are made into four of which the four ends of the wires above mentioned

page_text: dip when the magnet of the galvanometer is deflected. When the deflection is to
the opposite side the four wires change positions but they still dip into four of the
five pools of mercury. The four terminals of the cut circuit and a branch of one of
then are permanently fixed in these pools so that a deflection of the magnet right
or left reverses the current brought into play. The fact that a drop of mercury
stands well above the surface on which it rests makes all this practicable. With a
galvanometer having a horizontal axis of oscillation all these effects are more easily
and certainly brought about; and although the superior delicacy of the former
instrument makes it desirable to be able to use it as I propose the excellence and
certainty of mercurial connections renders a similar use of the latter very
important. Electro magnets may be used for the same purpose.

page_text: I, JAMES ENRIGHT of 202 Holland Road, Kensington, Electrician do hereby
declare the nature of my invention for ELECTRICAL RELAYS and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement:--
•
My invention has for its object improvements in the methods of completing,
breaking and reversing currents.
In many cases where it is necessary to establish Electrical contacts by move-
ments mechanical or otherwise, it is very desirable that the energy used in making
the contacts should be reduced to a minimum To effect this is the object of my
invention.
For this purpose I bring the terminals of the circuit it is required to establish
into mercury cups and then arrange that a piece of wire shall have its ends
plunged into the mercury so as to bridge over the gap in the circuit. A relay on
this principle may be worked by very small currents. Take a delicate reflecting
galvanometer which I shall call the relay galvanometer The magnet is suspended
by a fibre. A delicate Aluminium wire is attached to the magnet and hangs
vertically. Its lower end dips into a pool of mercury. At some distance from the
lower end of this wire a branch is fixed at right angles to it. This branch is then
bent downwards at right angles to itself. There is thus formed a rectangle
wanting the lower side. When the magnet is at rest the plane of this rectangle is
in the magnetic neredian. When the magnet is deflected by a small current the
free end of the branch traces out an arc of a circle. At a suitable position on this
arc a second pool of mercury is made. The terminals of the circuit to be completed
dip permanently into these mercury cups. When a deflection takes place under
these conditions the circuit will be completed through the Aluminium wire. The
deflections are limited by stops The circuit thus completed is understood to
contain a source of Electricity and any apparatus which it may be required to
oporate.
A deflection to the opposite side is made by means of a third pool of mercury to
complete a second local circuit in precisely the same way, and if the local circuits
be made to consist of the coils of a doubly coiled galvanometer (sounder) the
connections are easily made so that deflections of the delicate galvanometer
(produced by a small current from a distant station) are repeated on a sounder
operated by a local battery. Only one local battery is required and its current
passes through one coil of the sounder (galvanometer) or the other according as one
or the other local circuit is closed by the deflection to right or left of the relay
galvanometer The current passing through one local circuit deflects the needle of
the sounder in one direction; passing through the other local circuit it deflects it
(needle of sounder) to the opposite direction.
With a galvanometer having a horizontal axis on which the needle turns, this
make and break of local circuit is more easily effected. A piece of light wire is

page_text: bent into a semicircular arc and attached at its middle point to a prolongation of
the axis of the galvanometer so that the axis is tangential to the arc, and so that
when the needle is deflected the ends of the wire shall dip into two pools of
mercury situated on a platform which is fixed at a lower level than the axis If
the terminals of the local circuit be permanently connected with these pools the
circuit is completed at every deflection of the galvanometer towards the side on
which the bent wire is fixed. The local circuit is understood to contain a battery
and the apparatus it is desirable to operate.
It is perfectly clear that an Electro-Magnet may be used for the same purpose.
A light lever is delicately poised, and to the shorter arm is attached a picco of soft
iron. The Electro-magnet is placed in close proximity to the soft iron and in such
a position that when it is excited it will cause the end of the longer arm of the
lever to descend. At the end of this longer arm is fixed the bent wire which on
descending dips into two mercury pools and so completes the local circuit as before.
A morse instrument may be conviently worked by such relays.
I convert it into a reversing (polarized) relay as follows:-Two light pieces of
Aluminium wire are fixed together at their middle points by non-conducting
material at a suitable angle. They are then fixed by the middle points aforesaid
to the end of the vertical Aluminium wire attached to the needle of the relay
galvanometer Their plane should be horizontal. Their four ends are now bent
downwards. Care must be taken that they are not short circuited by the vertical
wire.
Five pools of mercury are made on a platform of suitable non-conducting
material and placed so that the down-turned ends of the two crossed wires dip into
four of them when the needle of the galvanometer is deflected to the right. I call
these pools A, B, C, D, respectively and they are situated approximately at the
angles of a square. The positive pool of the local battery is connected permanently
to A, and the negative to B. The pools A and B are elongated so that any hori-
zontal movement of the wires dipping into them shall not break contact. In this
they differ from the other three which are circular and smaller. The two ends of
the local circuit containing a sounder or other apparatus are connected permanently
to C. and D. one to each. A deflection to the right then closes the local circuit
causing the circuit to enter at C. and quit at D. When the deflection ceases the
needle returns to the magnetic meridian bringing with it the system of wires
attached to it and withdrawing them from the pools C. and D. and so breaking the
local circuit. The fact of mercury standing well above the surface on which it
rests makes all this practicable. Let us now suppose a deflection to the left. The
wire ends dipping into A. and B. though disturbed are not withdrawn from the
mercury. The wire end which in the last case dipped into C. now dip into D. and
that which in the last case dipped into C. now dips into D. and that which in the
last case dipped into D is now beyond D. at a point I shall call c situated so
that D. is midway between C and c. At c is the fifth pool of mercury. The pool c
and Care.electrically connected and therefore the local circuit is again closed but
in this instance the current enters at D and quits at C. Deflections of the relay
galvanometer in opposite directions therefore produce currents in the local circuit
in opposite directions.
The magnet of the relay galvanometer is generally suspended by one or more
fibres of unspun silk, but I sometimes prefer to float it and the light aluminium
wire attached to it in the pool of mercury into which the latter dips. The variation
in the magnetic field which causes the deflection of the needle is generally produced
by a coil surrounding it when there is an opening between the coils sufficient to
allow the light aluminium wire to pass to the mercury cup underneath. But
I prefer to produce the change of field by a different disposition of the wire
composing the usual coil. A portion of it is coiled on the permanent magnet
which governs the relay galvanometer needle; the other portion of it is coiled on a
soft iron magnet in such manner as to insure that when a current passes, the

page_text: governing magnet shall be neutralized and the relay needle will be placed by the
joint action of both poles of the now excited soft iron magnet in such position as to
secure the light aluminium wire being placed in the mercury pool as already
described. When the current is reversed at the distant station the poles of the
soft iron magnet is reversed and the relay Galvanometer needle flies to the
opposite side, and places the light aluminium wire in the other mercury pool.
The coils round the magnets may be in series or in multiple arc.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what
I claim is
(1.) A relay in which a circuit is closed by the use of mercury cups and a piece
of wire moved by an excited Electro-magnet substantially as described.
(2.) A relay in which a circuit is closed by the use of mercury cups and a piece
of wire moved by the deflections of a galvanometer needle in a vertical plane
substantially as described.
(3.) Relays in which the contacts are made by the use of mercury cups and one
or more wires moved by the deflections of a magnetic needle in a horizontal plane
substantially as described.
(4.) The method herein described of producing deflections of a magnetic needle
by the action of an Electric-current on a combination of permanent or temporary
magnets substantially as described.
(5.) The method herein described of repeating on a doubly coiled sounder the
deflection of a magnetic needle capable of being moved by a very small change of
field substantially as described.