Improvements in Electrical Induction Apparatus.
Year: 1898

page_text: Date of Application, 6th Dec., 1898-Accepted, 15th Apr., 1899
COMPLETE SPECIFICATION.
Improvements in Electrical Induction Apparatus.
I, THOMAS BURTON KINRAIDE, of 38, Spring Park Avenue, Boston, in the State
of Massachusetts, one of the United States of America, Electrician, do hereby i
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement;-
My invention is an improvement in induction apparatus, and has for its prin-
cipal object the provision of an apparatus capable of unlimited high frequency
without danger of self-destruction or breaking down.
Induction coils, as ordinarily constructed, are wound in disc form, the discs
being placed side by side, usually in a columnar or tubular form over a central
core, so that of course the coils are shortest, and hence offer least resistance, at
the centres of the discs or next the core, and the highest potential is at the out-
side, i.e. at the circumference of the disc, where the coils are the longest.
I have departed entirely from this principle, and have produced a flat coil in
which the highest voltage is at the shortest turns, and the lowest voltage is at
the longest turns, or, in other words the voltage increases inversely as the
resistance.
In its simplest form and preferred embodiment, my invention comprises a
coarse primary of few turns, and a fine secondary of many turns preferably
coaxially arranged, the secondary being retained in a special box and the primary
being confined to the low voltage or circumferential portion of the secondary.
The details of construction and the more complete embodiment of my inven-
tion, and the more striking phenomena thereof wiH be set forth in the course of
the following description, reference being had to the accompanying drawings,
and the invention will be more particularly defined in the appended claims.
In the drawings in which I have shewn preferred embodiments of my inven-
tion, Fig. 1 is a central vertical section of a simple coil or apparatus illustrating
one form of my invention;
Fig. 2 is a top plan view thereof, on a reduced scale and partly diagrammatic
in order to give a clear understanding thereof;
Figs. 3 and 4 are perspective details of insulators or separators employed;
Fig. 5 is a view similar to Fig. 4, shewing a complete embodiment of my in-
vention;
Fig. 6 is a top plan view thereof, partly diagrammatic.
Fig. 7 shows diagrammatically a variation of the winding.
In a box A of any suitable shape and size desired, being herein shewn in
Figs. 1 and 2 as circular, and in Figs. 5 and 6 as oblong with rounded ends, I
mount a primary B and a secondary C, a partition D preferably of glass being
interposed between the primary and secondary if desired, although it may be
omitted.
The box A has preferably a removeable bottom a and top a¹, Fig. 5, these
parts being preferably constructed of vulcanite or other insulating material.
When a partition D is employed, a ledge a³ may be moulded, stamped or

page_text: turned, if desired, on the inner wall of the box on which the partition may be
seated, and for neatness of construction the top also will preferably rest on a
similar ledge.
The top and bottom may be screwed or otherwise secured to the edges of the
walls or rim of the box, although I wish it understood that the details of the
enclosing box may be infinitely varied within my invention.
I wind the secondary C of fine wire and such area as is desired in the form of
a thin flat disc, and secure it by suitable means in one of the sides of the box,
herein shewn as the upper side, the securing means being herein shewn as com-
prising a plurality of glass rods c arranged in pairs oppositely placed above and
below the secondary and together constituting a holding grid; it is obvious
that this grid may be made in any form, the parallel bars being preferred merely
for convenience.
Having properly positioned the secondary between its holding rods c, or such
other holding devices as may be used, I preferably connect the terminals of the
secondary with a current sufficient to. raise the secondary to a considerable heat,
and then pour into the box a melted insulating compound E preferably of rosin
and beeswax sufficient to fill the box and entirely cover the secondary, preferably
also covering the holding rods e as is indicated in the figs., maintaining the
heat for a sufficient time to ensure that the melted rosin and wax shall have per-
meated into every interstice of the secondary and its neighbouring parts.
The primary when used within the box is put in position in the same manner
excepting that no holding grid is necessary therefor inasmuch as the inherent
rigidity of the coarse wires or ribbons prevent any buckling or warping thereof
under the action of the heated insulating compound.
The result is that when the insulating compound has hardened, the primary
and the thin flat disc of the secondary are insulated absolutely.
In view of the fact that my secondary is made of such fine wire and in the
form of a thin disc, it is necessary that it should be positively held by a grid-like
holder while the wax is being poured, as otherwise it would work out of shape.
The rods may be held at their ends by blocks c¹, as shewn in Fig. 4, or a
more convenient construction is that shewn in Fig. 3, where it will be seen that
the rods are severally provided with heads and are tied together simply by
wrapping a piece of silk thread c³ around the ends thereof; this latter construc-
tion is extremely convenient.
It will be observed that the partition D is cut away at its middle portion so
that it will be understood that both sides, or in other words, the entire apparatus,
is poured at once with the insulating compound.
The compound which I have mentioned is normally solid, and therefore there
is no tendency in the apparatus to leak, but, on the contrary, it is substantially
one piece or solid without any danger of loosening or getting injured.
Moreover, if from any cause whatever any heating effects have been produced
at any point in the apparatus, it is evident that the fusible insulating com-
pound will be softened or melted sufficiently to cause it automatically to flow
around the heated portions and maintain perfect insulation.
I prefer to employ a primary made as illustrated in full lines in the figs.,
where it will be seen that it consists of a flat helix of coarse wire or ribbon-like
metal, although it may be in other forms, for instance as indicated in dotted
lines at B in Fig. 5.
I have shewn both primary and secondary as circular, although it will be
understood that they may be square, oval or any other shape desired, oval for
instance being preferable where it is desired to get a long spark gap in an
instrument of the form shewn in Fig. 1.
The primary may be removeable from the box, or, if desired, carried outside
thereof, provided its proper relation to the secondary be maintained.
In the above description I have purposely omitted all technical-details of con-
struction in order to present.my invention in its broad features and in its sim-

page_text: plicity, although it will be understood that proper binding posts and connec-
tions will be provided, as indicated at 62, 63, Fig. 1, and that the other usual
features of regulation will be used in connection therewith including a break,
condenser, &c.
The apparatus is well adapted for use in wireless telegraphy.
The inner terminal of the secondary is shewn at e as extending in a central
post a to a usual adjustable electrode a³, and the opposite terminal of the
secondary is shewn in Fig. 1 as terminating at a thimble or ferrule in a
socket a, which may contain any suitable electrode, a ring discharger a being
shewn in place therein.
Referring to Figs. 5 and 6, it will be seen that I have provided two
primaries B2, B3, connected together at 6, and two secondaries C³, C³, electri-
cally connected by a contact ring or ferrule similar to that already described.
The two primaries and secondaries are separated by an insulating block A
which constitutes a portion of the box, and they are embedded in insulating
compound precisely the same as described in the simpler form of the apparatus
shewn in Fig. 1, it being understood that the connecting wires of the primary
and secondary are carried through insulating tubes as is indicated at a Fig. 5.
The inner terminal of each of the secondaries C2, C3, connects with a central
post a containing an electrode a³, as already described, and the thimble or
ferrule e, shewn in Fig. 5, as stopped by a plug a', is adapted to receive a dis-
charge ring a or any other form of electrode although usually it will be stopped
by the plug as shewn.
Fig. shews a primary winding B as surrounding secondaries, being inter-
mediately pinched together in the shape of an hour-glass so as to more directly
influence the secondaries, the latter presenting opposite polarities at their centre
terminals.
The primary is restricted to the circumferential portion of the secondary,-that
is to say, it is located in the vicinity of the outer or larger turns of the secondary
in the form of an annulus having a large central aperture.
The result is that I am enabled to obtain exceedingly high frequency without
destructive heating.
The intensity of the electrical fluid is enormously increased at the centre of
the coils, and nearly all the lines of force of the entire coil are concentrated upon
the central portion thereof; and the construction is such that this condition is
maintained, that is to say, there is an enormous propulsive discharge from the
electrode at the centre of the coil, and there is scarcely any discharge from the
outer electrode thereof, at c³.
This will be understood by referring to Fig. 1, where I have indicated by dotted
lines the discharge effects; the discharge takes place, or may take place, like
radiant flames collected by a ring, as shewn in Fig. 1, or, by removing the ring
or turning the electrode at some other angle, this radiant discharge simply
shoots out into space.
One great advantage besides that already pointed out, of the high frequency
and enormous discharge, is that there is no fear of melting down the coil; here-
tofore in induction coils it has been necessary to exercise extreme care in regu-
lating the discharge terminals so as to prevent too great resistance between them,
as otherwise the apparatus would at once short circuit itself and quickly be
ruined, whereas in my present invention, all this is done away with.
While I have herein described a preferred embodiment of my invention, I wish
it understood that very many changes and rearrangements may be resorted to
without departing from the spirit and scope of my invention, and that I am not
limited to the details.
Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what
I claim is:-
J. An induction apparatus comprising a thin, flat secondary of fine wire and

page_text: many turns embedded in a shallow box containing fusible insulating material,
and a coarse primary of few turns arranged coaxially of said secondary and con-
fined to the peripheral portion thereof.
2. An induction apparatus comprising a thin, flat secondary of fine wire and
many turns embedded in fusible insulating material, and a coarse primary of
few turns arranged coaxially of said secondary and confined to the peripheral
portion thereof, said primary being also contained in the fusible insulating
material.
3. An induction apparatus comprising secondaries in the form of flat coils,
and a primary winding of few turns surrounding said secondaries, the latter
having regions of high voltage at their centres, and regions of low voltage at
their peripheries, when in action.
4. An induction apparatus comprising of primaries connected together in series
at one of their terminals, combined with a separate secondary for each primary,
said secondaries having regions of high voltage at their centres, and regions of
low voltage at their circumferential terminals when the apparatus is in action.
5. An induction apparatus comprising primaries connected together, and a
secondary for each primary said secondaries being respectively located substan-
tially coaxially relative to their primaries, and each being wholly or mainly
within the primary, the latter being adjacent the circumferential portion of the
secondary only, whereby a large propulsive discharge may be maintained at the
- central terminal of the secondary with an inappreciable discharge at the circum-
ferential terminal thereof.
6. An induction apparatus comprising primaries connected together in series
at one of their terminals, combined with a secondary for each primary, said
primaries and secondaries being constructed and arranged to maintain high vol-
tage at the centre of each secondary, and low voltage at the circumferential
terminals thereof, the inner terminal of one of said secondaries being positive
and the inner terminal of the adjacent secondary being negative.
7. An induction apparatus comprising coarse, short, flat-coiled primaries con-
nected together, and corresponding long, fine secondaries wound in the form of
flat coils, each primary being wound with a large central aperture, and having
its coils restricted to the area adjacent the longer of the turns of its secondary.
8. An induction device comprising a box having a closed bottom and an inter-
mediate partition, said partition extending to the walls of the box parallel to
the bottom, a flat coil of a single thickness of wire being contained between
the partition and the bottom of the box and confined to that portion thereof
adjacent the walls of the box, and a flat coil constituting a secondary being con-
tained in the box on the opposite side of said partition and extending approxi-
mately to the centre of the box, the box being filled with, and said primary and
secondary being embedded in, a fusible insulating substance normally solid.
9. An induction device comprising a box having a closed bottom and an inter-
mediate partition, said partition extending to the walls of the box parallel to
the bottom, a flat coil of a single thickness of wire being contained between the
partition and bottom of the box and confined to that portion thereof adjacent
the walls of the box, and a flat coil constituting a secondary being contained in
the box on the opposite side of said partition and extending approximately to
the centre of the box, the box being filled with, and said primary and secondary
being embedded in, a fusible insulating substance normally solid, said secondary
being retained from warping by means of an insulating" grid comprising bars
extending across it both above and below.
10. An induction apparatus comprising a box having compartments and
removeable tops therefor, each compartment containing a coil constituting a
primary, and a second coil constituting a secondary, said coils being coaxial
with each other and the secondary extending within the primary, said coils
being embedded in fusible insulating substance normally solid and filling" said
several compartments, said box having insulated passages connecting said boxes,
:

page_text: and said several primaries having one of their terminals communicating through
said passages, and a discharge post or device for the central terminal of each
secondary.
Dated the 6th day of December 1898
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicant.