Improvements in Galvanometers.
Year: 1893

page_text: Date of Application, 5th Dec., 1893
Complete Specification Left, 18th Aug., 1894-Accepted, 22nd Sept., 1894
PROVISIONAL SPECIFICATION.
Improvements in Galvanometers.
We, EDWARD W. JEWELL, of Wheaton, Du Page County, Electrical Engineer,
and WILLIAM ZIMMERMAN, Patent Attorney and Lawyer, of 164 Dearborn
Street, Chicago, both in the State of Illinois, do hereby declare the nature of this
invention to be as follows:-
Two similar bell-magnets are placed with like poles facing on the same axial
line having between them a ring-armature leaving a small space between the
magnets and armature. Diametrically opposed on said ring are two coils formed
of a single piece of insulated wire of which the central part connects said coils
which are free to move on said armature. Said coils are carried on arms of a
metal shaft having its axis coincident with that of the magnets. The ends of said
shaft turn in insulated jewelled bearings. Said insulations, each, also hold an arm
whereof the end thereof holds the end of a coiled spring of which the opposite or
inner end is held on an insulated sleeve on said shaft. Said spring turns said coils
and holds them to one end of the magnetic field. The outer ends of said coils are
carried inward on the arms of said shaft, one going to the upper and the other to
the lower hub of said spring to which they are fastened. The arms of said
springs are connected with binding-posts through which the outer connection is
made. This arrangement forms an amineter.
A resistance coil is also placed in the circuit with the instrument whereby it may
be made to answer as a voltmeter.
To the moving mechanism, preferably to one of said coils, is attached an
index which is provided with a scale for reading the work of the instrument,
in volts, or amperes, changing from the one to the other through appropriate
shunts.
The above-named moving mechanism is carried in a frame which is held,
adjustably, within the magnets on an axis coincident with that of said magnets
and shaft whereby the index may be adjusted to zero.
When a properly directed current is passed through said coils they will move
forward in the magnetic field against the resistance of the helically coiled springs
thus causing the index to indicate desired measurements.
Dated this 17th day of November 1893.
EDWARD W. JEWELL.
WM. ZIMMERMAN.
COMPLETE SPECIFICATION.
Improvements in Galvanometers.
We, EDWARD W. JEWELL, of Wheaton, Du Page County, Electrical Engineer,
and WILLIAM ZIMMERMAN Patent Attorney and Lawyer, of 164 Dearborn
Street, Chicago, both in the State of Illinois, United States of America, 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:-
In the accompanying sheets of drawing:
Fig. 1 shows a central, vertical, longitudinal section of said combined ammeter

page_text: Fig. 2 shows one of the magnets as seen on the inside, or under-side of the bell.
Fig. 3 shows a transverse central vertical section taken at right angles to the
plane which cuts Fig. 1, but showing only the mechanism inside of the bell
magnets and a section of the ring armature outside of, and carried, by it.
Fig. 4 shows Fig. 3 in plan view.
Fig. 5 shows in vertical section, on an enlarged scale, fragments of the left
hand pole and armature, as the instrument stands relative to the observer, with
its surrounding coil and ends of its wire, one connected to the helical spring, and
the other going to the opposite coil; said springs, the shaft, and arm being also
shown in section.
Fig. 6 shows in diagrammatic form the construction of the instrument in its dual
capacity.
Like letters of reference refer to like parts.
The object of this invention is to produce an ammeter which may readily be
converted into a voltmeter, be conveniently and safely portable, casily set up, and
uninfluenced in any magnetic field in any position in which it may, relatively, be
placed; wherein the magnetic resistance is reduced to a minimum and, practically,
uniform condition and the field is of constant strength throughout the entire travel
of the moving coil, and the stability of the permanent magnets increased to a
maximum degree, and thereby, the calibration of the instrument made constant ;
wherein all portions of the moving coil so cut lines of force as to leave no dead
wire, thus reducing the necessary weight and inertia effect to the smallest quantity
attainable, and making its action, practically, dead beat and more sensitive than
any instrument of its class heretofore produced, and provided with like-reading
horizontal and vertical scales, a fuse as a safety device, and other advantages, as
hereinafter set forth.
To attain those desirable ends said new and improved instrument is constructed
in substantially the following manner; namely:-
Two permanent bell, magnets, n, n, are placed in the same axial line with their
like poles facing each other, between which is held an annular soft iron armature, g,
leaving between it and those poles air-spaces of about one thirty second of an inch,
more or less, for coils, or loops, a, a, to move freely therein.
Said coils are secured to the ends of tubular aluminum arms, b, b, on the shaft,
or staff e, stepped in jewelled bearings, p, having its axis coincident with
that of the magnets, n, n, and secured to the internal frame, i, on the insulating
plates, h.
Said internal frame, i, is made of brass, or other suitable material, and is held in
a larger brass frame, v, secured to the lower magnet, n, by screws t, t.
The base of said frame, i, has a short, stout, shaft, , which turns in a close
fitting hole in the outer frame, v, and thereby permits axial adjustment so as to
bring the index, m, to zero, also vertical adjustment to bring the coils, a, a, into
the centres of the spaces in which they move.
Said frame, v, consists of a bottom piece, vl, having two annular segments rising
within and fitting against the magnets, n, m, to near the top of the upper
one which is fastened thereto by means of screws at, r, or in any other suitable
manner. There are lugs, 2, on the outer surface of the segments which hold said
ring, 9:
To one of said coils or loops, is attached a long and slender index, m, pointing in
the same direction of the axes of the arms, b. Said index is here shown bent
upwards from its horizontal direction then it is again parallel to its first direction
over a horizontal scale, k, and reflecting surface, ², beyond which it points down-
wards in front of and parallel to a vertical scale, k¹, and reflecting surface, k³.
The length of said scale is as great as the travel of said index, and the
casing, w, which holds the magnets, is extended on one side to hold said scales
and index; said mirrors, k², k³, serve to avoid parallax errors in reading the
instrument.
The coils, a, a, are wound with a single piece of fine insulated copper or other

page_text: suitable wire its middle portion passing through the tubular arms, b, and one
of its ends passing from one of said coils through one of said tubular arms to
the insulated hub on the spindle, e, of one of the helical springs, c, and the other
end of said wire from the other coil, through the opposite tubular arm, b, to the
insulated hub of the other helical spring, c. The insulation of said hubs is a rubber,
or equivalent material, tube on the shaft, e.
The other ends of said springs, c, are held by arms, 7, which form a part
of the rings, d, which are also insulated on said rubber pieces, h. Said arms, q,
are connected by wires, /,, with the binding-posts, 3, 4, also with binding-
post, f.
">
A resistance coil, in some convenient place, as under the scale, may be placed
in circuit with the instrument whereby it may be made to answer as a voltmeter.
The manner in which the resistance-coil is connected is shown in the diagrammatic
construction of the instrument shown in Fig. 6.
When the circuit enters through the posts, f³, f, the instrument acts as an
ammeter; when it passes through the posts, f³, f³, (V A. and V) then as a
voltineter.
Ouly small fragments of the rings, d, are shown in Fig. 6 with their arms, 7.
There is a fuse, f, in the circuit to prevent injury from excess of current.
Four blocks of fibre, o, or like suitable substance, keep the magnets and
armatures at proper distances from each other and at the same time act as stops to
the motion of the coils, a, and a wooden or other suitable case, w, incloses the lower
part of the instrument which also forms a base upon which the sheet-metal case, w,
is supported to inclose the scales and index and the moving coils and upper part of
the instrument, generally, as shown.
The joints formed by said metal casing are closed by strips of felt, w', or other
suitable material.
The motion of the coils, a, is derived from the properly directed current in the.
looped conductor.
Said conductor moving in a field of uniform strength with lines of force in the
proper direction as indicated.
It is evident that the top magnet may be omitted and that such an instrument.
would still be serviceable.
The radial extent of the magnetic field and armature are substantially alike;
a general feature of this invention whereby magnetic flux enters the sides instead
of the edges of the armature which thus permits a construction through which may
be attained the highest efficiency of a magnetic coil, or coils surrounding and
deflected on said armature.
I desire it to be understood that I employ the term "galvanometer" in its
generic sense, that is to say as embracing ammeters, voltmeters and other like
instruments.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that
what we claim is:
1st. The combination with a permanent positive and negative pole with arinature
of substantially like radial area as said field, of a resisting couple and deflecting
conductor on coincident centers, substantially as specified.
2nd. The combination with permanent magnetic fields with armatures of sub-
stantially like radial area, of a pivoted conductor surrounding said armature,
impelled in said field, and mechanisin to return it to its starting point, substantially
as specified.
3rd. The combination with magnetic field and superimposed armature of sub-
stantially like radial area whereby said armature receives its magnetic flux from
its sides instead of its edges, of a pivoted and looped conductor moving on said
armature and mechanism to return it to its starting point substantially as
specified.

page_text: 4th. The combination with bell shaped magnets and annular armature between
their poles, of a counteracted conductor, surrounding said armature, an index and
scale, substantially as specified.
5th. The combination with permanent and similarly magnetic fields with
armature and a scale, of an index and a looped conductor surrounding said
armature and means to counteract said conductor, substantially as specified.
6th. The combination with permanent similarly magnetic and opposite fields
with a fixed armature surrounded by a moving, looped, counteracted conductor ;
an index on said conductor, of a resistance-coil and scale substantially as
specified.
°
7th. The combination with permanent and similarly magnetic fields with a fixed
armature and a scale, of an index and a looped conductor surrounding said
armature, and mechanism to counteract said conductor, substantially as specified.
8th. The combination with a magnetic field and armature, scale and mirror, of a
deflecting coil surrounding said armature, with index to said scale on said coil,
substantially as specified.
9th. The combination with a magnetic field having an armature, scales, at or
near right angles to each other, of a deflecting coil surrounding said armature with
index for both of said scales, substantially as specified.
10th. The combination with circular permanent and similar magnetic fields and
armature therefor, and a scale, of a movable looped conductor surrounding said
armature centered in said field, and index to said scale and means to counteract
said conductor, substantially as specified.
11th. The combination with a scale, circular, permanent and similarly magnetic
fields and armature therefor, with same axial centers, of movable, diametrically
opposed, looped conductors surrounding said armature, on said center, an index to
said scale, où said conductor, and means to counteract said conductor, substantially
as specified.
12th. The combination with a series of scales placed at different angles to each
other, circular, permanent, and similarly magnetic fields facing each other, and
armature therefor with same axial centers, of movable looped, diametrically
opposed conductors surrounding said armature on said center, an index to said
scales on said conductor and means to counteract said conductor, substantially as
specified.
13th. The combination with one or more scales and mirror acting therewith,
circular, permanent, and similarly magnetic fields, and armature therefor, with
same axial centers, of movable, diametrically opposed looped conductors surrounding
said armature, on the same center, an index to said scales, on said conductor and
means to counteract said conductor, substantially as specified.
14th. The combination with permanent magnetic fields with a fixed armature
and movable looped and counteracted conductor surrounding said armature with
index thereon, and scale of a resistance-coil in circuit with said parts, substantially
as specified.
15th. The combination with an armature and a pivoted deflecting-coil thereon
of a concentrically pivoted index-adjusting support, substantially as specified.
Dated this 17th day of August 1894.
J. G. LORRAIN, M. Inst. E.E., M. Inst. M.E.,
Chartered Patent Agent.