IMPROVEMENTS IN THERMO-ELECTRIC AND MAGNETIC APPARATUS
Year: 1866

page_text: PROVISIONAL SPECIFICATION left by Lieutenant-Colonel James Baker
at the Office of the Commissioners of Patents, with his Petition, on
the 20th December 1866.
I, Lieutenant-Colonel JAMES BAKER, of the Army and Navy Club, Pall
Mall, in the County of Middlesex, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THERMO-ELECTRIC AND MAGNETIC APPARATUS,"
to be as follows:-
My improvements relate to the production of electric currents by the
application of heat to metals or their alloys, to the conduction, insulation, and
intensification of those currents, and to their application in producing motive
power, part of these improvements being appplicable to electric currents pro-
duced in other ways. It is well known that bars of certain metals and alloys
being heated at one end more than at the other give rise to currents of
electricity, which may be conducted from these bars and applied in their
circuit to any of the purposes for which electricity is employed. I make such
bars with longitudinal grooves, and I cast them with the end of a conducting
wire embedded in their substance near to the extremity where heat is to be
applied. I carry this wire through tubes of non-conducting material, such as
pipe clay, laid in the longitudinal grooves, and I arrange a number of such
bars with their conducting wires and insulating tubes side by side, coupling
several together by soldering the end of one conducting wire from the
extremity of one bar to the opposite extremity of another bar. Several bars
so coupled form a thermo pile or battery, one end of which being heated while

page_text: the other is kept cool, or cooled artificially, an electric current is produced,
which may be applied to the excitation of magnetism, or to other purposes to
which electricity is usually applied. I apply heat to the end of the pile either
by the combustion of jets of gas mixed with air, or by exposing the ends of
the pile-to the radiant-beat of plates forming the exterior of a furnace or stove.
In order to regulate the temperature of such plates, and to prevent it from
rising above the melting point of the thermo metal used in the pile, I fix in
connection with the stove a small steam boiler heated by the flue of the stove
in such a manner that when the heat is excessive steam is generated, and
blows into the fire so as to damp it. In order to intensify and collect the
electric currents I pass them through helical conductors wound on iron cores,
the conductors from several piles being wound side by side on the same core,
but insulated from one another. I afterwards lead the several conductors to
a fixed disc or cylinder, consisting of conducting and non-conducting material
arranged in alternate spaces, each of the conductors being connected to each
.of the conducting spaces. I mount a metallic spring or roller on an axis, by
turning which I cause it to pass over these conducting spaces successively,
and I connect a conductor to the axis of this spring or roller, so that during
rotation it receives the electricity from each of the several conductors in suc-
cession. I form the conducting spaces of such shape that the spring or roller
immediately before leaving one begins to make contact with the next, so that
the current is never totally interrupted. The current so collected is conveyed
through the apparatus in which it may be employed, back to the pole or poles
of the battery opposite to those whence it started, thus completing its circuit.
I apply the currents so generated and collected, or currents derived from other
sources, to the production of motive power by means of an apparatus of the
following description :-I mount on an axis a disc, which is called hereafter
a rotating disc, formed of an odd number of iron parts connected firmly
together, and to the axis by non-magnetic material. Each of the faces of
each part is grooved spirally, so that conducting wires can be bedded in non-
conducting material; in these grooves such wires being wound in the grooves
from the circumfererce to the centre of each part, or vice versâ ; each end
of each such conducting wire is connected to a conducting spring or roller
which bears against a commutator, to be hereafter described, in such a manner
that when the disc revolves currents of electricity can pass alternately in
opposite directions through the spirally coiled conductor of each separate part.
By this means each face of each part receives alternately a north and south
polarity. Facing each side of this disc, and as near to it as may be without
actual contact, I fix a disc consisting of an even number of iron parts mag-

page_text: netically insulated from one another, each such part being spirally grooved to
receive conducting wires, as above described, and these conducting wires being
led respectively to the opposite poles of a battery, so that a current of elec-
tricity transmitted through them renders the faces of the iron parts constantly
magnetic. I arrange the direction of the coils and currents so that the faces
of these parts have polarities north and south alternately in succession. As
during the working of the apparatus the polarity of each of those parts
remains unchanged, permanent magnets may be used instead of the electro-
magnets above described. The commutator referred to above consists of a
disc or cylinder formed of conducting and non-conducting parts arranged
alternately, the conducting portions being connected some with the one pole,
and some with the other pole of a battery, so that when the rollers or springs
connected with the wires of the rotating disc pass successively over the con-
ducting portions of the commutator the currents of electricity passing through
these wires are changed in direction, and the polarites of the different parts
are thus changed from north to south and from south to north alternately.
By properly arranging the positions of the conducting portions of the com-
mutators attraction and repulsion are alternately produced between the faces
of the parts of the rotating disc and the faces of the parts of the fixed discs,
in such order that rotation is maintained in one direction, and this rotation
may be reversed by reversing the direction of the electric currents. Several
such rotating discs may be mounted on one axis, each faced by fixed discs, as
above described. I prefer to make the conducting portions of the commu-
tators of such form that the conducting rollers or springs which bear on them
shall begin their contact with one portion just before contact is actually
broken with another so as to avoid sparks at making and breaking contact.
In cases were permanent magnets are used instead of electro-magnets I
prefer making them in the following manner :-I first compress the steel of
which the magnet is to be made in the direction of the intended magnetic
axis; I then heat it and place it within a coil of electric wire with its ends
applied to the poles of electro-magnets so arranged that its intended magnetic
axis lies parallel to the magnetic meridian and allow it to cool in that position,
or I cool it by a cold draught always moving in one direction.