Improvements in the Construction of Rheostats or similar Electrical Instruments.
Year: 1891

page_text: Date of Application, 23rd July, 1891
Complete Specification Left, 22nd Apr., 1892-Accepted. 28th May, 1892
PROVISIONAL SPECIFICATION
Improvements in the Construction of Rheostats or similar
Electrical Instruments.
CHARLES LAWrence Baker, Electrical Engineer, of Cadby Hall Works,
Kensington, W., and WOODHOUSE & RAWSON UNITED LIMITED, Electrical
Engineers and Contractors, of 88 Queen Victoria Street, London, E.C., do hereby
declare the nature of this invention to be as follows:-
This invention relates to electrical instruments by means of which variable
resistances are inserted into circuit or circuits carrying an electric current, and
is designed to afford a more perfect and reliable form of instrument for the said
purpose.
To this end, I take two discs of any suitable insulating material, mounted upon a
spindle which is capable of rotation or not as the case may be. In these said discs
I drill corresponding holes of any required number, through which I thread any
suitable metal or alloy, in the form of wire, preferably German silver, which forms
the medium of resistance, or I may insert rods or U shaped pieces of metal rod, or
suitable alloy, the ends of which I join in any convenient manner, so as to form a
continuous conductor from end to end, in such a way that an electric current
entering at one end must traverse the whole length before reaching the
other end.
Attached to the instrument is a rubbing contact which is also capable of rotation
or not as the case may be.
Among the advantages I claim for this instrument are, reduced cost of manu-.
facture, economy of space, and freedom of risk from damage by overheating.
Dated this 22nd day of July 1901
CHAS. L. BAKER.
WOODHOUSE & RAWSON UNITED, LIMITED,
W. T. Stutchbury, Secretary.
COMPLETE SPECIFICATION.
Improvements in the Construction of Rheostats or similar
Electrical Instruments.
CHARLES LAWRENCE BAKER, Electrical Engineer, of Cadby Hall Works,.
Kensington, W., and WOODHOUSE AND RAWSON UNITED LIMITED, Electrical
Engineers and Contractors, of 88 Queen Victoria Street, London, E.C., 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:—
This invention relates to electrical instruments, by means of which variable
resistances are inserted into a circuit or circuits carrying an electric current, and
is designed to form a more perfect and reliable form of instrument for the said
purpose.
To this end, having reference to the accompanying drawings, in which similar
letters refer to similar parts, I take two discs A and B shown in section in Figs. I
and II, and the upper disc A in plan in Figs. III and IV of any suitable insulating
material, and mount them upon a spindle C, which is capable of rotation in the
design shown in Figs. I and III, but fixed in Figs. II and IV, the whole being
mounted upon a suitable base D Figs. III and IV. In these said discs A and B

page_text: Fig. I, I drill corresponding holes of any required number, shown in Fig. III,
through which I thread any suitable metal or alloy preferably German silver,
which forms the medium of resistance, in the form of wire, as shown in Fig. V,
forming a continuous conductor, or I may insert U shaped pieces of metal rod or
alloy Fig. IV, their ends being joined by a metal junction piece E Fig. VI, shown
in detail in Fig. VIII, so as to form a continuous conductor, or again I may use
single rods of metal or alloy Fig. VII, joined at each end by metal junction
pieces F and F Fig. VII shown in detail in Fig. IX, or a more elaborate form of
the junction piece for the upper disc A is shown in detail in Fig. X, for use in
design shown in Fig. IV, so as to form a continuous metal conductor. I have used
the words continuous metal conductor, but I do not wish it to be understood that
the conductor is a complete circle, because in Fig. V the two ends of the wire are
not joined, and in Figs. VI and VII one metal junction piece is left out, one end
of the conductor in each case being permanently connected to the spindle C,
which again is joined to a terminal mounted on the base D, the other end 1
being free.
In the case of Figs. I and III in which the spindle C rotates, a rubbing
contact H making contact with the outside of the conductor thus inserting more
or less resistance as the spindle is turned to the right or left. In the case of Figs. Il
and IV where the spindle C is fixed, the junction pieces G, G etc. Fig. IV, shown
in detail in Fig. X, are in the form of contact plates, upon which rest the arm K
Fig. IV of a switch, which arm is capable of rotation, thus inserting more or less
resistance as it is turned to the right or left, the switch arm in this case must of
course be insulated from the spindle, or if preferable it may rotate upon and make
connection with the spindle; the spindle C in all cases being connected to a
terminal mounted on the base D, and the other end of the conductor also being
connected to a terminal, in the case of Fig. III through the rubbing contact H,
and in the case of Fig. IV direct.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what :
I claim is:
An apparatus for the insertion of variable resistances in an electric circuit,
substantially as described and for the purposes set forth.
Dated this 21st day of April 1892.
Dated this 21st day of April 1892.
CHAS. L. BAKER,
WOODHOUSE & RAWSON UNITED, LIMITED,
A. L. Foley, Secretary.