Improved Electrical Conductor.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improved Electrical Conductor.
I, PHILIP HENRY HOLMES of Gardiner in the County of Kennebee and State
of Maine United States of America Mechanical Engineer do hereby declare the
nature of this invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :—
"
The object of my invention is to make an electrical conductor (such for instance
as a pencil for electric arc lights or a commutator brush for dynamos motors or the
like) that will not be consumed or wear away so quickly as usual. This object I
attain in the following manner.
The arc-light pencil is made essentially of plumbago in a finely divided state,
which is moulded into the desired form by pressure and then treated with some
binding material, such as a drying oil, for instance, which will make the particles of
plumbago adhere to one another, and in order, to produce a pencil which will with-
stand the more or less rough usage to which it is subjected, I mix with the plumbago
sufficient finely divided fibre, such as for example divided wood fibre, to give it the
desired strength. The proportion of fibre to plumbago may be varied according to
circumstances, but I prefer to have as much plumbago as possible in the pencil and
largely in excess of the other ingredients.
I have obtained very good results from pencils in which the proportions of
plumbago to fibre vary from four to one to thirty five to one.
I find that an arc-light pencil made in accordance with my invention lasts con-
siderably longer than does a pencil made of the ordinary gas carbon and will also
give a more satisfactory light.
In making a commutator brush I use a compound of plumbago and fibre bound
together by a suitable binder, preferably drying oil. Such a brush not only con-
stitutes a good electrical conductor, but it also reduces the friction between the
brush and commutator, hence, the material of the brush will not wear away so fast
as do the brushes made of metal or carbon in the usual manner.
I have used brushes made of my improved material on dynamos and motors with
excellent results, the brushes running smoothly, preventing sparking and otherwise
improving the machine.
The pencil or brusb, may if desired, be made of plumbago, with a suitable oil
binder, or the plumbago may be combined with fibre, as circumstances require.
In making either the arc-light pencil or the commutator brush, I prefer to apply
thereto by plating or otherwise a coating of copper or other suitable electrical
conducting metal, which not only strengthens the pencil or brush but also adds to
its conductivity.
The material may be used for electrical contact points and in fact for any electrical
use to which such a material can be applied.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is.
First An electric conductor (such as for example an arc-light pencil or com-
mutator brush) made of finely divided plumbago compressed and united by an oil
binder.
Second An electric conductor (such as for example an arc-light pencil or
commutator brush) made of plumbago and fibre, substantially as hereinbefore
described.
Third An electric conductor (such as for example an arc-light pencil or

page_text: commutator brush) composed of finely divided plumbago; finely divided fibre, and a
drying oil, moulded into the proper form substantially as hereinbefore described.
Fourth-An electric conductor (such as for example an arc-light pencil or com-
mutator brush,) of plumbago with a coating of electrical conducting metal.
Fifth An electric conductor (such as for example an arc-light pencil or com-
mutator brush,) of plumbago and fibre with a coating of electrical conducting
metal.
Dated the 16th day of June 1891.
J. H. JOHNSON & Co.,
Agents.