IMPROVEMENTS IN ELECTRICAL CONDUCTORS, COUPLINGS, SWITCHES TERMINAL CONNECTIONS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Stephen Henry Emmens at the Office
of the Commissioners of Patents on the 15th December 1882.
STEPHEN HENRY EMMENS, of Soho Square, in the County of Middlesex, Actuary
"IMPROVEMENTS IN ELECTRICAL CONDUCTORS, COUPLINGS, SWITCHES
TERMINAL CONNECTIONS
"
AND
My invention has reference to an improved method of arranging and constructing
the various parts of an electric circuit, so as to ensure better contacts and insulation,
greater safety against fire, and quicker and more artistic laying of wires.
For fixed contacts, such as are required for the poles of batteries and dynamos,
switches, commutators, plain coupling, and the like, I employ screws with conical
ends working into bosses pierced with oval holes. By this means I am enabled
to wedge up the wires against the bosses to any required degree. Where, for
any reason, it is desired to use terminals of the ordinary (cylindrical flat-faced
form, I improve the contacts by interposing washers with roughened bearing faces.
For contacts that have to be frequently made and unmade, I employ couplings
consisting of two hooks either interlocking or mutually gripping_contact pegs
placed on the sides of the respective hooks. In the former case I tighten the
contacts by means of screw nuts working on the shank of each hook, and bearing
against the head of the other, by which means I obtain a flexible coupling. In
the other case I insert a wedge between the two contact pegs, and so tighten the
contact.
For cross couplings, such as in the case of branches from a main circuit, I employ
two hooks with bases having bearing faces cut at an angle to the line of the hook.
These bases are connected by a screw so placed that if the two hooks hang on the
branch with the main line resting on the bearing faces, the turning of the screw
causes the branch and main lines to approach each other in a direct line with any
required degree of force.
For the making and breaking and changing of circuits I employ switches con-
structed so as to make contact in the plane of movement, instead of at right angles
to such plane, as is usually the case. I thus ensure contacts which cannot work
[P11

page_text: loose, and by making the moveable contact piece in the form of one or more rollers,
I am able to maintain clean surfaces, and to prevent sparking.
In order to guard against fire from excess of current, I employ either a cut out
or a safety regulator. I construct my cut-out by enclosing a wire of lead or other
suitable metal or alloy in a tube of ebonite or other insulating material. This wire
is in connection with a terminal at each end of the cut-out, which by means of
such terminals is placed in the circuit desired to be protected, and the apparatus
may be so adjusted that on the current increasing to a dangerous extent, the wire
fuses and breaks the circuit, and yet no fused metal can escape. I construct my
safety regulator by interposing in the circuit to be protected the coil of an electro
magnet with an armature carrying the plug of a resistance coil. By weights or
springs or other suitable means, I can adjust the armature to any required degree,
so that on the current in the circuit attaining undue strength, the armature is
moved and throws the resistance into circuit.
In order to guard against fire from short circuiting, earthing, or the formation of
arcs where the lines pass over unprotected woodwork or other inflammable material,
including switch-boards and the like, I first treat the wood or other material with
a solution of tungstate of soda, and then cover it with asbestos paint, paper, or mill-
board.
In order to guard against fire from the heating of the air and other substances in
the neighbourhood of an elastic wire, I place in such neighbourhood an apparatus
consisting of a closed iron drum containing mercury, which as the air becomes
warm and expanded is driven up a tube and there makes contact with the wire of
an electric bell or other signal, so as to give warning that an undue degree of heat
has been developed at the point where the safety apparatus is placed.
For the better fixing of wires and cables to walls and other supports, I employ
cleats consisting of a screw leg with a head at right angles to such leg, and for
covering the wires and cables I either use strips or ribbons of calico, silk, velvet, or
other suitable material, threaded at intervals with cross wires or rings, by means of
which the covering may be wrapped round the wires, or I coat the wires or cables
with coloured varnishes