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June 1, 1948.
Filed April 16, 1945
3 Sheets-Sheet 1
J1me 1, 1943-
3 Sheets-Sheet 2
Filed April 16, 1945
1/ @ll! 111/ 11111 1
///II III/
June 1, 1948.
Filed April 16, 1945
3 Sheets-‘Sheet 3
Patented June 1', 1948
Jacob H. Rubenstein, Builalo, N. Y.
Application April 16, 1945, Serial No. 588,562
1 Claim. (Cl.
This invention relates to a magnetometer for
determining the direction or intensity of the
to permit of expanding or contracting the range
lines of force of a magnetic ?eld, such as the
earth’s magnetic ?eld, and which can be used
trol element.
or amplitude of movement of its pointer or con
Another object is to provide such a sensitivity
to determine the magnetic meridian oi the
.1 adjustment which does not alter the wave form
earth’s magnetic ?eld, its horizontal, vertical
of the response of the magnetometer when
and total force components and the angles of
rotated in a magnetic ?eld being measured. ,
inclination and declination thereof. Such mag
netometers have a wide range of uses, such as
Another object is to provide such a sensitivity
adjustment for a magnetometer which does not
10 act through a variable loading of the magne
in navigation instruments and as a traillc de
tector to operate in response to passing vehicles.
tometer but which directly varies the number of
lines of force to which the magnetometer is re
In such uses it is desirable to provide a highly
sensitive magnetometer to measure slight changes
sponsive under a given condition, thereby to
avoid the variable factors inherent in adjustable
in these values. Further, these values are differ
ent at di?erent locations around the earth and 15 loading of a, sensitive instrument.
when using a magnetometer as a navigation in
Another aim is to provide such a sensitivity
adjustment which is regularly progressive in its
strument it is frequently desirable to permit of
action to permit a regular change in adjustment
compensation for these changing values by an
to compensate for regularly changing conditions.
adjustment of the sensitivity or range of move
ment of the magnetometer.
Another purpose is to provide such a sensitivity
This application is a continuation in part of
adjustment which is itself sensitive and at the
my copending applications for patent Serial
No. 562,728, ?led November 9, 1944, for Method
and apparatus for determining the direction or
same time stable so as to remain in any ad
justed position regardless of operating condi
Another object is to Provide such a sensitivity intensity of the lines of force of a magnetic 25
adjustment which can be used in connection
?eld, now abandoned, and Serial No. 576,343,
with any magnetometer employing an‘ antenna
?led February 5, 1945, for Magnetometer.
member for attracting the lines of force being
The desirability of such adjustment is referred
to in my copending application for Method for
ruary 15, 1945. For example, to maintain a
constant amplitude or range of movement of the
Another object is to provide such a sensitivity
adjustment which is easily operated. is ‘compact
and light in weight and is not liable to set out
of order under conditions of severe-and constant
pointer or control element of the magnetometer .
determining the position or a body with refer
ence to the earth, Serial No. 578,075, ?led Feb- '
in traveling toward the earth's magnetic equator, 35 Other objects and advantages will appear from
the following description and drawings in which:
a progressive‘decrease in the sensitivity, i.e. scale
compression, is required to compensate for the
Fig. 1 'is an elevational view of the antenna
increase in the horizontal component or the de
members, movementv and scale of a magne
crease in the angle of inclination as the mag
tometer embodying the present invention, the
netic equator is approached. Reverse compen 40 support or casing being eliminated for clarity,
this magnetometer having one form of sensi
sation is required in traveling from the earth's
magnetic equator toward either magnetic pole.
One of the principal objects of the invention 7
tivity adjustment.
Fig. 2 is a top plan view of the antenna mem
is to provide a magnetometer the sensitivity of
bers movement and sensitivity adjustment shown
which is greatly augmented by the use of per 45 in Fig. 1.
manent magnets which serve to attract a large
Fig. 3'is'an end view of one of the antenna
members shown in Figs. 1 and 2.
sheath or cylinder of the ‘lines of force from
the surrounding magnetic ?eld for measurement.
Fig. 4 is a perspective oi the movement shown
in Figs. 1 and 2.
Another object is to so arrange these perma
nent magnets that they do not alter the re 50 Fig. 5 is a view similar to Fig. 2 and showing
a modi?ed form of sensitivity adjustment‘ em
sponse of the magnetometer except to increase
bodying the invention.
the amplitude of the response.
Another principal object of the present in
Fig. 6 is a view similar to Fig. 2 and showing
vention is to provide an adjustment for the sen- '
another modi?cation oi the sensitivity adjust
sitivity, to any desired degree, of a magnetometer 65 ment embodying the invention.
Fig. 7 is an isomagnetic chart of the lines of
force surrounding the form of magnetometer
shown in Fig. 6, the magnetometer being dia
grammatically illustrated as parallelv with the
extremity of each antenna member. The over
lapping portions of the pairs l2. l5 and I8 of
lines of the earth's magnetic ?eld or in zero
degrees relation thereto.
Fig. 8 is a view similar to Fig. 7 showing the
laminations can be secured together in any suit
able manner as by the axially positioned brass
eyelet or grommet 20 shown and the opposite
extremities of these laminations can. be secured
to the tubular core II in any suitable manner.
magnetometer turned to a 45° position with ref
It will be noted that each antenna member is
composed of a group of metal laminations of high
crence to the lines under measurement.
Fig. 9 is a view similar to Figs. '7 and 8 and 10 initial magnetic permeability which are arranged
in the general form of a cylinder, this being an
showing the magnetometer turned to a 90° posi
important feature of the magnetometer. How
tion with reference to the lines under measure
ever, it is also an important feature of the mag
netometer that this cylindrical form of the lami
Fig. 10 is a view similar to Fig. 8 but showing
the permanent magnets adjusted further out 15 nations of each antenna member be broken by
one or more longitudinally extending gaps, such
wardly from the antenna member and illustrat
as the four gaps 2|, these gaps breaking up the
ing the reduced sensitivity obtained by this ad:
otherwise ring form of the antenna in cross
justment of the permanent magnets.
section and hence any substantial tendency to
Because of its simplicity, stability, accuracy
and independence from _an outside power source, 20 ward transverse polarization.
the sensitivity adjustment forming the subject of
The two antenna members [0, l0’ are arranged
in axially opposed relation to each other with
the present invention is shown in connection
the overlapped ends of their laminations spaced
with the magnetometer forming the subject of
to provide a gap 22. In this gap and in approxi
my said copending patent application Serial No.
mate alinement with the axis of the two antenna
576,343, ?led February 5, 1945. However, forms
members is arranged the free end of a polarized
of the sensitivity adjustment can be used with
lever which forms a part of the movement illus
other forms of magnetometers, such as the mag
trated in perspective in Fig. 4.
netometer described in may said copending ap-_
This movement includes a shaft 23 which is
plication Serial‘ No. 562,728, ?led November 9,
supported at its ends in. bearings 24 in the casing
or support of the magnetometer. An indicating
In the magnetometer illustrated herein an
hand .or pointer 25 is fast to this shaft and
tenna members are employed to attract a large
traverses a scale 26 which is shown as having a
sheath or cylinder of the lines of force of the ?eld
zero centerpolnt, although any appropriate grad
to be measured, this feature supplying the nec
uation indicia can be employed. A hairspring
essary power for operating the magnetometer so
as to eliminate the necessity for an external
source of power. A pair of such antenna mem
28 has one end secured to the shaft 23 to bias
the pointer 25 toward its zero position, the other
end of this hairspring being secured to the sup
port or casing for the magnetometer. As previ
bers are provided in spaced coaxial arrangement
and a lever polarized by a permanent magnet is
ously indicated, for clarity, this support or casing
rotatably mounted with its free polarized end in
is not illustrated.
the concentrated ?eld between the two antenna
Fast to the shaft 23 is an iron vane 30, this
members, thereby to be attracted toward one or
iron vane being secured by a lever arm 3| which
the other depending upon the polarity of the
embraces the shaft 23 so that the iron vane is,
antenna members as determined by the position
of the antenna array with reference to the mag 45 in effect, a lever fast to the shaft 23 and with its
free end generally in line with the axis of the
netic ?eld under measurement.
antenna members l0, l0’ and at right angles
The antenna members, indicated generally at
thereto in its neutral or zero position so that the
I0 and I0’, are identical in construction, a pre
free end of the lever is capable of being attracted
ferred form being shown in the drawings in
which each antenna member includes a round 50 toward one antenna member ID or the other
tubular core ll of brass or other non-magnetic
antenna member ID’.
The iron vane is polarized and for this pur
material so that each antenna member is hollow
and generally round in cross section. On this
pose a small strip 32 of aluminum is secured to
tubular core is wrapped a plurality of lamina
one end of the iron vane to project toward its
tions of high initial magnetic permeability and
axis of rotation. The projecting end of this
strip 32 of aluminum carries a small permanent
low coercive force. These'laminations are shown
magnet 33, this permanent magnet preferably
as being arranged in pairs, one pair 12 extending
being of high coercive force alloy to produce a
along one side of the core ll, around that end of
?eld of high magnetic strength. This perma
the core which opposes the other antenna mem
ber, and along the opposite side of the core, the 60 nent magnet is shown as having its end of posi
tive polarity in contact with the edge of the
ends of the laminations terminating adiacent
iron vane so that the entire iron vane is of posi
the outer extremities of the cores. The legs or
tive polarity, as indicated.
parallel portions of this pair of laminations are
preferably transversely curved to ?t the core ll.
The magnetometer, as above described, can be
Another pair l5 of these laminations is L-shaped 65 used to determine the magnetic meridian of the
in longitudinal section, the laminations being
earth’s magnetic ?eld, the horizontal, vertical
curved to fit one or the other sides of the tubular
core I l and having an end I 8 of reduced width
and total force components of the ?eld, and the
angle of inclination and declination of the lines
of force thereof. For example, if the magnetom
overlapping the pair I2 of laminations at the
inner extremity of each antenna member. A 70 eter is rotated so that the axis of the antenna
members l0, l0’ traverses the magnetic meridian,
third pair l8 of these laminations is likewise
L-shaped in longitudinal section and curved to
when the axis of the antenna members becomes
‘ ?t the fourth side of the tubular core II and has
parallel with the lines of force of the ?eld, a large
an end IQ of reduced width overlapping the ends
_ sheath or cylinder of the lines of force is attracted
I6 of the pair l5 of laminations at the inner 75 from the surrounding ?eld into the antenna mem
bers l8, l8’ and forms a concentrated ?eld across
the gap 22. The polarity of the antenna array
will depend upon the polarity of the lines of force
of the ?eld. Thus, if the array is arranged so
that the right hand antenna member 18' is par
allel with the lines of force and projects toward
the polarity of the array is reversed as compared
with the condition ?rst assumed, the pointer 25
the north geographic pole of the earth its right
magnetometer is effected by adjustably moving
is at the opposite extremity of the scale 26 as com
pared with the position ?rst assumed.
In the form of the invention shown in Figs.
1-4, the adjustment of the sensitivity of the '
hand or outer end is of plus polarity by induc
the antenna members I8, I8’ toward and from
tion and its opposite or inner end is polarized
each other. For this purpose each antenna mem
negatively by induction. Conversely, the polar 10 her I 8, I8" is shown asslidingly mounted in a tube
ization of the opposite or left hand antenna mem
85 of brass or other n0n~magnetic material, these
ber I 8 by induction is negative at its outer or
tubes 85 being ?xed in any suitable manner to
left hand end and positive at its inner or right - the support or casing (not shown). Each of these
guide tubes 85 is shown as being provided with a
hand end. Since the iron vane 88 is positively
polarized it will. under these conditions, be at-‘ 15 longitudinalslot 86, these slots being in‘ line with
each other and being located near the opposing
tracted toward the right, as viewed in Figs. 1 and
2, or toward the negatively polarized inner end
ends of the guide tubes. An arm 88 of brass
- or other non-magnetic material is shown as fixed
of the right hand antenna member 18'. This
movement of the iron vane 88 to the right swings
to the brass core I i of each antenna member, each
the pointer 25 to the left hand extremity of the '20 of these arms 88 projecting outwardly through
a corresponding slot 86 and having a threaded
scale 26.
' eye 88 at its outer end. The openings in the eyes
As the array osf antenna members l8, I8’ is
88 are reversely threaded with respect to each
swimg out of alinement with the lines of force
other and are in line with each other to receive
of the surrounding ?eld, the number of lines of
force attracted to the array to traverse its axis 25' the ends of a threaded adjusting screw 48, of
progressively diminishes.
Consequently, the
brass or other non-magnetic material, the oppo- _
strength of polarization of the array diminishes
and the iron vane 88, under the in?uence of the
site ends of this screw 48 being likewise reversely
threaded. At its center this screw 48 is shown
. hairspring 28, moves away from the weakening
as carrying a ?xed adjusting wheel 4|, the pe
negative pole at the inner end of the right hand 30 riphery of which can'be calibrated as indicated
antenna member l8’ thereby to progressively
at 42, this wheel also being of brass or other non
magnetic material. It will be seen that upon
move the pointer 25 to the right toward the cen
tered or zero position on the scale 26. When the
array, so rotated out of alinement with the lines
of dome of the surrounding ?eld, reaches a posi
tion where it is at right angles to ‘the lines of
manually turning the adjusting wheel 41 and
screw 48 the arms 88 will be drawn together or
35 moved apart, the relative position of these arms '
being indicated by the calibrations 42.
the arms 88 are fast to the antenna members l8,
l8’, these antenna members are accordingly ad
all of the lines of force of the surrounding ?eld
justed with reference to each other, these anten
pass through the array transversely. Conse 40 na members sliding in the supporting tubes 85.
quently, the array is not axially polarized and the
Moving the antenna members away from each
pointer 25 is held at its zero position solely under
other, other conditions being equal, increases the
leakage ?ux path around the polarized iron vane
the in?uence of the hair-spring 28.
As the assumed rotation of the magnetometer
38. Hence there is decreased magnetic reaction
between the polarized iron vane and the antenna
in the magnetic meridian is continued from this
members resulting in a decreased, amplitude of
neutral or zero position, the number of lines of
the pointer movement along the scale‘ 26. This
force attracted to the antenna array to traverse
its axis progressively increases. ‘However, the - provides decreased sensitivity. Conversely, on so
adjusting the antenna members i 8, l8’ toward
right hand antenna member 18', as viewed in
Figs. 1 and 2, is now being rotated toward the 50 each other, less leakage of the lines of force be
tween the opposing ends of the antenna mem
south geographic pole of the earth and hence
force none of these lines of force are attracted
to the array to traverse its axis. In this position
the polarity of the array is reversed. The inner .
bers occurs around the polarized iron vane 38 and .
hence the response in the movement of the, polar
end of the right hand antenna member i8‘, as
viewed in Figs. 1 and 2, is now polarized positively
ized iron vane is increased so that the pointer
by induction and the inner end of the left hand 55 has an increased amplitude of movement along
the scale 26 when the magnetometer is rotated
antenna member l8 negatively by induction.
Consequently, the positively polarized iron vane
in the ?eld under measurement.
In the form of the invention shown in Fig. 5,
88 is attracted to the left, as viewed in these fig
the adjustment of the sensitivity 01' the magne- ,
ures, so as to cause the pointer 25 to traverse the
right hand side of the scale 26. >
60 tometer is achieved by providing an adjustable
shunt, in the form of a piece of high perme
As the antenna array is so rotated toward re
ability material. across the gap between the
alinement with the lines of force of the earth’s
antenna members i8, I8’ so that an adjustable
magnetic ?eld, the number of lines of dorce at
amount of ?ux can be' bypassed around the iron
tracted to the array to traverse its axis progres
sively increases, a larger and larger cylinder of 65 vane 38 and thereby increase or decrease the
_ these lines being so attracted. As a consequence
amplitude of the meter reading. The shunt 45
the pointer '25 is moved further along the right
is shownas being of semi-cylindrical channel
form parallel with and embracing, to an ad
hand side of the scale 26 until the point is reached
justable extent, the opposing ends of the antenna
where the array is again in alinement with the
lines of force of the surrounding ?eld and the 70 members l8, l8’. This shunt is shown as adjust
able toward and from the antenna members in
maximum number of lines of- force are attracted
a direction at right angles'to the axis thereof
to the antenna array to traverse’ its axis. Con
and to guide the shunt in this movement it is
sequently, the polarity of the array is at maxi
shown as provided at its ends with ?xed pins
mum strength. and the pointer 25 is at the ex
treme right hand position on the scale’ 26. Since 75 46 which extend through guideways provided'in
a pair of guide lugs 48 which form part or the
drawn together or moved apart the relative posi
magnetometer casing (not shown). At its center _
' the shunt‘ is shown as having ?xed thereto a
tion of these permanent magnets being indicated
threaded stud 49 which projects parallel with the
guide pins 46. This threaded stud is engaged by
by the calibrations M. '
In the operational the form or the invention
shown in Fig. 6, when the array of antenna mem
an adjusting nut 50 which is rotatably mounted
bers I0 is rotated, as shown in the isomagnetic
on a supporting lug Ii projecting from the mag
chart, Fig. 7, to a position parallel witl. the lines
netometer casing (not shown). The nut It can
of force or the surrounding magnetic ?eld, that
be turned by an integral adjusting wheel 52 which
is, at zero degrees angularity, one of the per
can be calibrated as indicated at 53.
10 manent magnets, such as the permanent magnet
The mounting for the nut 50 permits rotation
56 as shown, is in a position of like polarity to
of this nut but prevents axial movement ‘thereof
the surrounding ?eld and this magnet provides
and it will therefore be seen that turning the
a closed ?eld which'includes its antenna mem
hand wheel "moves the threaded stud ll axially
ber “I, this permanent magnet II and antenna
and hence moves the shunt II toward and from 15 member I ll being thereby, in eiiect, removed from
the axis oi’ the antenna mei?iers. As a greater
the array in this position. The other antenna
amount or ?ux will be shunted through the mem
member I0’ is, however. polarized by its per
ber ‘I as it is moved closer to the antenna mem
manent- magnet Is in unlike relation to the sur
bers, a smaller proportion oi’ these lines or force
rounding ?eld and hence attracts a large sheath
pass through the polarized iron vane ill and hence 20 or cylinder of lines or force from the surround
the amplitude of movement 01' the pointer along
ing ?eld to traverse the axis of this other antenna
the scale is reduced for the magnetic force under
member I0’, the size or the sheath or cylinder
measurement. Conversely. moving the shunt 45 , of lines or force so attracted being greatly aug-'
away from the antenna members ii, iii’, by ad
mented by the presence of the permanent mag
iustment oi the wheel 82, reduces the shunted 25 net. As this other antenna member I0’ is axially
?ux and increases the number of lines, or force
polarized, the iron vane will be moved in response
‘ e?'ectlve upon the polarized iron vane 30 thereby
thereto and since the permanent magnets l8, I!
to expand the range of movement or the mag
are shown as having their positive endsopposing
netometer. '
the antenna members, the inner end or this other
In the form of the invention shown in Fig. 6, 30 antenna member III’ is positively polarized and
the adjustment of the sensitivity is achieved by
hence ‘repels the positively polarized iron vane
adjustably introducing one or more permanent
magnets to excite the antennas so as to bring
them up to a higher point on the BH curve
thereby to increase their initial permeability.
30. . Accordingly, the pointer 25 will be moved
along the scale 26 in a corresponding direction to
the maximum amplitude.
Upon rotating the array from this zero to a
45° position with reference to the lines 01' force
under measurement, as shown in Fig. 8, the
lines or force attracted by the permanent magnet
58 and its antenna member I l’ progressively de
40 crease and the lines of force attracted by the
In Fig. 6 the antenna members l0, iii’ are each
antenna member in and its permanent magnet
shown as enclosed within a tube 55 of brass
68 increase.
or other non-magnetic ' material, these tubes
When the array is rotated to the 90° position,
serving to support the antenna members from the
as shown in Fig. 9, the antenna members I0, I.’
magnetometer casing (not shown) and also serv
are at right angles to the lines of force and as
ing to support permanent magnets 58, 58 at the
the permanent magnets 58, 58 are in opposition
opposite ends ‘of the array for movement toward
to each other and or the same strength and
andirom the antenna members. These per
equidistant from the iron vane Iii, these magnets
manent magnets are shown as arranged in mag
do not attract any external lines of force to pass
netic opposition to each other, their positive 50 axially through the array. Therefore the entire
poles being shown as arranged in opposition and
array is in a neutral position and the iron vane
adjacent the ends of the antenna members i0,
30 is not in?uenced and the pointer is held at
Iii’, respectively. Each of the tubes 55 is shown
the zero position on the scale 28 by the hair
as being provided, alongside the enclosed per
spring 28.
manent magnet, with a longitudinal slot 59, these
It will therefore be seen that the array with the
slots being arranged in line with each other. An
opposed permanent magnets 56, 58, as shown in
Further, in such use of permanent magnets at
least one of the magnets serves to attract a large
sheath of the lines of force oi’ the surrounding
magnetic ?eld to traverse the axis of its antenna
arm 60 of brass or other non-magnetic material
Fig. 6, operates in the same manner as the array
is shown as ?xed to each permanent magnet,
shown in Figs. 1-4 except that the predominating
each of these arms Gil projecting out through the
magnet attracts a larger sheath or cylinder of the
corresponding slot 59 and having a threaded eye 60 external lines of force than the unexcited array
6| at its outer end. The openings in the eyes 61
‘of Figs. 1-4 in all positions other than the 90° or
are reversely threaded with respect to each other
270° position. In the 90° or 270° position neither
and are inline with each other to receive the
the excited nor unexcited array attracts the ex
ends or a threaded adjusting screw 62 oi’ brass
ternal ?ux to pass axially therethrough and both
or other non-magnetic material, the opposite 65 register zero.
ends of the screw 62 being likewise reversely
As the permanent magnets are adjusted out
threaded. At its center this screw 62,is shown
wardly, as shown in Fig. 10, by turning the call
as carrying a ?xed adjusting wheel 63 the pe
brated wheel 83, fewer lines of force are attracted
riphery of which can be calibrated, as indicated
to the array to traverse its axis and consequently
at 6,4, and this adjusting wheel also being of brass 70 the pointer traverses a smaller range of the scale
or other non-magnetic material.
28 in response to an external ?eld of a certain
As with the form of the invention shown in
Figs. 1-4, it will be seen that upon manually .
value. Thus, so moving the permanent magnets
outwardly moves the operating point of the array
on the BH curve so as to, in e?ect, decrease the
turning the adjusting wheel 63 and screw 62 the
arms 60 and permanent magnets 56, 58 will be 75 initial permeability of the antenna members
i0, it’. As a more demonstrable explanation of
this e?ect of shifting the permanent magnets
66, 69 outwardly, as illustrated in Fig. 10, as these
permanent magnets are shifted outwardly each
forms an increasingly enlarging closed magnetic
?eld around the permanent magnet itself. This
\is obtained by the elimination of the adjacent
antenna member i0, M’ from this ?eld. As the
antenna member is therefore excited to a re
tivity of any antenna magnetometer are provided.
I claim as my invention:
In a magnetometer, a pair of longitudinally
spaced antenna‘ members having high permea
bility and concentrating an external magnetic
?eld in the space therebetween, means in said
space and responsive to changes in the ?ux of
the concentrated ?eld therein, means measuring
changes in the response of said ?ux responsive
duced degree by the permanent magnets its 10 means, means for varying the number of lines
attractive e?‘ect is reduced and fewer lines of
force of the external ?eld are attracted to traverse
the axis of the array. In consequence a reduced
force is exerted on the iron vane 30 and scale
of force in said concentrated. ?eld in said space
independently of said external ?eld, comprising
means for supporting said antenna members for
movement toward and from each other, and
compression results.
15 means for adjustably moving said antenna mem
Comparing Fig. 8, in which the permanent
bers toward and from each other in equidistant
magnets 56, 58 are adjusted close to the antenna
relation to said flux responsive means to pro
array, with Fig. 10, in which these magnets are
vide a sensitivity adjustment for the magnetom
adjusted to positions remote from the array,
comprising a screw having its ends re
it will be seen, by actual count, that the number 20 eter,
threaded with respect to each other, an
of lines of force entering the antenna array in
internally threaded member screwed on each
Fig. 8 exceed the number entering the antenna
end of said screw and operatively connected with
array in Fig. 10. In these ?gures the array is
a corresponding one of said antenna members,
at the same angle relative to the magnetic me
and means for turning said screw.
ridian. It will therefore be seen that adjusting
the permanent magnets 56. 5B outwardly de
creases the number of lines of force effective upon .
the iron vane 30 and hence ‘decreases the sensi
tivity or causes scale compression or the mag
netometer. Conversely, inward adjustment of
these permanent magnets increases the sensi
tivity of the magnetometer.
From the foregoing it will be seen that the
form of the invention shown in Figs. 6-10 pro
vides a highly sensitive magnetometer, as com
pared with that shown in Figs. 1-4, by the addi
tion of the permanent magnets 56, 58. Further,
by arranging these magnets in magnetic opp0sition to each other and having these permanent
magnets of equal strength and equally spaced
from the center of the array, the wave form of
the magnetometer, as shown in Figs. 1-4 is not
altered by the addition of the permanent magnets
'56, 58, only the amplitude being increased. Fur
The following references are of record in the
file of this patent:
Romain __________ __ Feb. 13, 1917
Coley ____________ __ June 1, 1926
Babbitt __________ .._ Feb. 11, 1930
Herrick __________ __ Feb. 17, 1931_
- 1,863,421
Rieber ____ _._ .... __ June 14, 1932
Tear ____________ __ June 14, 1932
Thorne __________ .. Jan. 12, 1937
Hoare ____________ _.. July 5, 1938
ther, in all forms of the invention stable, accurate 45
Great Britain ____ -.. Nov. 4, 1919 -
and easily manipulated adjustments for the sensi
France __________ .. Mar. 4, 1929
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