IMPROVED ARRANGEMENTS FOR ELECTRIC LIGHTING
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by James William Thomas Cadett at the
Office of the Commissioner's of Patents on the 11th October 1878.
JAMES WILLIAM THOMAS CADETT, of Camberwell Grove, in the County of Surrey.
"IMPROVED ARRANGEMENTS FOR ELECTRIC LIGHTING."
My Invention has for its object the sub-division of the electric current for
lighting purposes.
In carrying out my Invention I adopt mainly the following arrangements :-
An electric generator or generators of electricity is or are used, capable of
delivering a sufficient current, which may be considerably in excess of the amount
of current intended to be used. It will however be preferable to place a body or
bodies or resisting medium or mediums between the lamp and the source of
electricity, which offers sufficient resistance to the current so as to pass only that
amount of current sufficient for the lamp or light. In the case of many lamps or
lights a series of the said resisting mediums or bodies can be used, so as to place a
resisting medium between each lamp or light and the source of current. In the
case where different places arc illuminated from one source a resisting medium can
be attached to the cable supplying the current, one resisting medium to each place
to be illuminated, such resisting medium to be made to deliver the amount of
current required for each place. The current after leaving the resisting medium
may be opened out or divided or sub-divided between other or second resisting
mediums, and then delivered to different light or lamps; it being understood that
the resistance offered by the second resisting medium or mediums is or are pre-
ferably greater than the first resisting medium, so as to ensure steadiness of light
by sufficiency of current to the several resisting mediums, it being understood that
in this case a resisting medium is placed between each light or lamp and the current

page_text: from the first resisting medium. The resisting mediums may vary within reasonable
limits in their resisting power, so as to supply currents of required strength, as for
instance when a very powerful light is used the lamp can be attached direct to the
first resisting medium, when it will practically use all the current delivered by the
first resisting medium, the said resisting mediums being preferable made of carbon,
but not necessarily, so as resistance coils or other kinds of resistance may be used.
Resisting mediums may be employed which work automatically so as to deliver
practically the same amount of current during variations in the current supplied to
the said automatic resisting medium or mediums, it being understood that the main
current does not fall below the proper amount of current to be delivered by the
said automatic resisting medium or mediums, and if desirable the arrangements
described may be combined. Each automatic resistance medium is connected with
the cable or other source of electricity; the current enters the apparatus and passos
through an electric motor or engine, said motor being for the purpose of raising
an arm which carries a rod of carbon or suitable material. Any of the well-
know electric motors or engines may be applied. This rod of carbon or other
material dips into a cut of, mercury, or may be made to work against a suitable
conductor, so as to shorten or lengthen the conducting length of the carbon or rod or
other material, thus varying its resistance, such rod being preferably made or formed
of varying resistance. The end of the said carbon rod or other material which dips
in the mercury or works against a conductor having a higher resistance than the
other end held by the arm before mentioned. The higher resistance would preferably
gradully diminish towards the other end of the rod. An electro-magnet is used,
and a spring carrying armature faces the core of the magnet, this spring being
in direct conducting communication with the arm carrying the carbon rod.
Communication is made with the cup of mercury or other suitable conductor, and
thence to the electro-magnet, to the lamp, or to other resistance medium or mediums
to the lamp. The current passes by the motor or engine to the arm carrying the
carbon rod or suitable material into the cup of mercury or against other conductor
through the electro-magnet and to the lamp direct or through other medium to
the lamp. The current in passing actuates the motor and raises the arm carrying
the rod, the result being that the rod is lifted partly out of the cup of mercury, thus
increasing the resistance of the carbon rod, the effect being to weaken the current
in 'the electro-magnet, which allows the spring carrying the soft iron armature to fall in
contact with a point in conducting connection with the cable or source of current.
This short circuits the motor or engine, and practically puts it out of circuit, thus
keeping the current constant. When it is required to subdivide a current not much
in excess or under the amount desired to be used, lamps or apparatus may be used,
which practically offer the same resistance to the current whether alight or extin-
guished. For this purpose I use arrangements substantially as follows:-In cases
where a given current is required to be sub-divided, or divided between a series of
lamps, I prefer to use lamps so arranged that as the carbons draw apart, thus
increasing the resistance offered by the lamp by the resistance of the arc, a small
rod of carbon or other suitable material can be made to dip into a cup of mercury
so as to counterbalance the resistance of the electric arc, the current of course
passing through the carbon or other suitable material and the cup of mercury. For
this purpose the rod of carbon or other material can be moved by either of the arms
carrying the positive or negative carbons, or by means in communication with the
said arms.
Instead of the cup or vessel of mercury a suitable conductor can be
used, against which the carbon or other material can move so as to shorten or
lengthen the conducting length of the carbon or other material, thus varying its
resistance to counterbalance the resistance of the arc. Arrangements may also be
used in this case, so that if the light of any lamp should be extinguished communi-
cation can be made with resistance coils or other resisting bodies offering the same
resistance as the lamp when alight, so as to prevent the current from the extin-
guished lamp being used in the other lamp or lamps which would thus suddenly

page_text: increase their illuminating power. Communication is made with the said resistance
coils or other resisting bodies by a spring carrying an armature, which armature
when the lamp is alight is held by an electro-magnet, and prevented from making
contact with the resistance coils or other bodies, but when the lamp is out the
electro-magnet is out of circuit, the spring falling back, and makes contact with the
resistance coils or other resisting body or medium.