Improvements in Ships' Compasses.
Year: 1888

page_text: Date of Application, 11th July, 1888
Complete Specification Left, 1st Mar., 1889-Accepted, 22nd June. 1889
DE BUITIVATION.
Improvements in Ships' Compasses.
1, JOSEPH VON PEICHL of Fiume in the Austrian Empire, Lieutenant of the
Imperial Austro Hungarian Navy, and Director of the Hungarian Sea Navigation
Company Limited do hereby declare the nature of this invention to be as follows:-
In the Specification to Patent No. 3738 of 1878 (being a communication to
C. D. Abel from me) I described a construction of ship's compass with an arrange-
ment of "intensity multiplier and quadrantal corrector," more particularly described
with reference to Figs. 5 and 6 of the drawings, which device consisted of two
discs S¹S carrying iron bars in such a manner that the lower sides of the bars of tho
upper disc were situated somewhat above, and the upper sides of the bars of the lower
dise somewhat below the horizontal plane of the compass card, or in other words the
mean horizontal plane of the double system of iron bars forming the intensity multi-
plier and quadrantal corrector was made to coincide with the "horizontal plane" of
the compass card, such plane being that passing through the geometrical longitudinal
axis of the compass needles. The bars of both discs were mounted in a precisely
similar manner, the bars being of equal thickness but of such varying lengths, that
while the outer ends thereof all lie in a circle, the inner ends that are presented to the
compass card all lie in an ellipse.
The above described construction, as also the mechanism described in the
Specification for adjusting the same for correcting quadrantal deviations D and E and
the mechanism for correcting the semicircular deviations B and C have been proved
by experience to be open to the following objections.
First. In consequence of the quadrantal corrector having been placed in the
horizontal plane of the compass card, the small space existing between the compass
needles and the inner ends of the iron bars prevented the use of large sized compass:
cards, these being restricted to a diameter corresponding with the length of the
needles.
But at the present day compasses are largely used having cards of comparatively
large diameter with comparatively small needles, in order to increase the steadiness of
the card and to render the divisions of rhumbs and degrees more easily visible. So
that the said quadrantal corrector in the form described would be inapplicable to such
a construction of compass card, and if it could be so applied in the plane of the compass
card, it would render the compass of impracticably large dimensions.
Secondly. The said iron bars, in being inclined by the oscillating motions of the
gimbal rings, would cause considerable vibrations of the compass card, the apparatus:
described in the Specification offering no means for neutralizing such disturbing offects
of the bars.
..
Thirdly. Although the quadrantal corrector with elliptical arrangement, of the iron.
bars as shown at Fig. 5 of the drawings, will compensate quadrantal deviations D) and E
et it will at the same time produce an octantal deviation if the apparatus is to be
dapted for larger amounts of D. This octantal deviation, having around the whole
ircle of the compass eight maxima alternating in their sign, has a prejudicial effect.
n the shaping of a true course, and renders it more difficult to adjust the correctors..
or the deviations B, C, D, E. It also acts prejudicially on the construction of
orrectors with large amounts of quadrantal force (such as are now required in.
onning towers and for many steering compasses) the amount of octantal deviation
creasing with the amount of quadrantal force, which is augmented by increasing the
ifference between the major axis and the minor axis of the ellipse in which the inner
ads of the bars lie.
Fourthly. The said apparatus described with reference to Figs. 5. and 6 of the said.

page_text: Specification was not provided with any means for indicating the amounts of force
developed by the quadrantal corrector at different positions of the discs S¹ S around
the compass howl, and also the correctors B and C, Fig. 6 were not provided with
scales of force for rendering it possible to readjust the correctors independently of the
direction of the ships head and of sights.
Fifthly. The said construction does not allow of ready access to the mechanisms by
which the quadrantal corrector is adjusted and the mechanism as a whole requires to
be simplified and rendered of less weight.
My present invention relates to an improved construction of such compasses
whereby the above mentioned objections are obviated and whereby an improved typo
of compass of comparatively small size and sufficient power for any omorgoncies is
produced.
This improved compass may ho either of the ordinary kind, or it may bo a fluid
compass of any typo or description. The compass card has generally four needles,
mounted by preferenco according to the rules given in the Admiralty Manual for the
deviations of compasses; but a greater or less number than four needles may also be
used. The card is generally made of a larger diameter than would be necessary for a
given length of compass-needles in order to render the deviations more readily visible,
and for reducing, in non-fluid compasses, the vibrations of the needles. In such cases
the upper part of the bowl is made wider than the lower part, and the improved
quadrantal corrector is, according to the present invention, placed around such lower
part below the horizontal plane of the card, being made rotatable concentrically round
the central axis of the bowl and parallel to the horizontal plane.
In fluid compasses, the card is generally made of a size corresponding to the length
of the needles, and mounted with a floating arrangement for reducing the friction on
the parts to a minimum. But in such compasses cards of larger diameter can also
be used.
The improved quadrantal corrector consists of a double system of small bars of soft
iron mounted upon two superposed discs and laid around the lower part of the bowl.
below the horizontal plane of the card, as above stated, the said discs being rendered
independent by the gimbal rings from the rolling and pitching motions of the ship.
These discs aro rendered rotatable relatively to each other round the bowl by means of
gearing consisting simply of a toothed pinion situated between two segmental toothed
racks fixed respectively on the upper and lower discs, the pinion being actuated by
means of worm and worm wheel gear, the spindle of which passes through the upper
side of the apparatus, so that the pinion can be actuated for adjusting tho discs without
having to open the part of the binnacle underneath the compass. A clamping devico
is provided near the actuating spindle for clamping the two dises together. Each dise
carries by preference 32 iron bars, but a greater or less number can be used on both
or either disc. In consequence of the discs being situated below the horizontal plano
of the card, the resulting action and reaction between the compass needles and the
iron bars does not take place in a horizontal direction, but generally in a direction
inclined to the horizontal plane by an angle of about 45°.
With this arrangement it ovident that if the two sets of bars were made of equal
form and size, the upper set of bars would exercise a greater influence upon the
needles than the lower set; I consequently make the upper bars of a loss transverse
section and, if necessary, also of a less length, so as to increase their distance from the
needles, whereby the effect of both sets of bars can be rendered equal.
The arrangement of the bars, which is otherwise equal in both sets, is shewn
diagrammatically on the accompanying drawing in which 1, 2, 3 represent the bars of
soft iron of one of the discs, arranged symetrically with respect to the cardinal
points a, b, d, e and radially around the centre c which is supposed to lie in the per-
pendicular axis of the compass bowl passing through the centre of the compass
card.
The outer ends of the bars are generally arranged in a circle concentric to c, while
the lengths of the bars are so regulated that their inner ends lie in a curve of the.

page_text: This curve, which is an essential feature of my present invention, deviates from the
ollipso in such a manner that the bars situated intercardinally near m n o p are longer
than in the caso of the elliptic arrangement. The great and important object of this
new curve is to compensate, in addition to the quadrantal deviations D and E, the
octantal error caused by correctors with elliptical arrangement of the bars, as also by
G. B. Airy's correctors of quadrantal deviations, in other systems of compensation. In
addition, the mean directive force of the compass is increased in an analogous manner
to that with elliptically arranged bars.
Owing to the circumstance that the development of quadrantal force in any such
system of induction bars depends almost entirely upon the reciprocal action between
the inner ends of these bars and the compass needles, the arrangement of these inner
ends forms the most essential part of such an instrument. The above described curve
forms the basis for the size, type and qualities of a compass provided with such a com-
pensation, and the application of this curve has alone rendered it possible to place the
discs with tho iron bars below the horizontal plane of the card, without interference of
considerable octantal errors.
In some cases a single set of the above described bars may be used for compensating.
a constant amount of quadrantal deviation in which caso the main axis a: b. would
require to be placed parallel to the direction of the keel.
The lowered position of the bars has, in addition to the before mentioned advantages,
the further advantages, firstly of reducing the disturbances of the needles caused by
the vibrating motions of the apparatus within the gimbals, the reduction being effected.
to such a degree that it is unnecessary to employ means to paralyse them; secondly,
the stability of the apparatus within the gimbals is increased thereby, so that the
necessary stability can be obtained with less total weight of the instrument.
According to a further improvement, I apply to the quadrantal corrector a scalo
marked with D and situated upon the upper side of the upper dise, while an index on
the lower disc reaches up over this scale so as to shew the relative positions to which
the two discs are adjusted by the turning gear, and the proportionate force of the
corrector due to any position between that of the maximum and that of zero.
The maximum of quadrantal force is developed if the main axis a b of both discs
run parallel with the direction of the lubber line, which, on board, is considered to be
generally also the direction of the keel. This position is marked by 10 on the D scale.
In shifting the discs from this position by the turning gear, the long axis of the one
will be deflected to the one side and that of the other to the other, side of the keel,
forming an angle that will be bisected by the line of keel, the quadrantal forco
developed by such deflections being proportionate to the natural cosine of the anglo
formed, and these proportions are indicated by the D scale in decimals of a unit down
to zero.
By means of this scale the quadrantal corrector can be roadjusted without tho
employment of other means.
For the purpose of compensating with the improved corrector, not only the
quadrantal deviations D, but also the oblique part thereof called E, the two discs
clamped together are capable of being displaced from the direction of the keel to an
angle depending upon the relative values of the deviations D and E if the clamps
marked E are lifted.
An index shews the amount of displacement in degrees on a scale marked with +E
and E and situated on the periphery of a ring holding the apparatus and lying with
its axis in the gimbal ring, the axis being supported by antifriction rollers.
-
The compass bowl has the faculty of moving slightly round the vertical axis, after
aving lifted two screws marked with A at the bottom of the apparatus, in order to
displace the lubber line, and thereby correct, if required, the, constant deviation
denominated A, the scale of which is opposite to that of E. in the same ring. Under
ho base plate of the apparatus, centrally under the compass card, I fix two per-
pendicular brass rods carrying an adjustable weight for regulating the stability of the
nstrument, and also two receptacles for small magnets serving as correctors of the
emicircular deviations B and C, these receptacles being adjustable on the rods, which
'

page_text: .
hear scales of force for indicating the positions of the receptacles and the proportionate
force of the magnets placed in the same relatively to the compass needles. This
arrangement of the correctors B and C forms however no essential part of the improved
apparatus, and these correctors might also be placed down in the binnacle as in other
systems of compass compensation.
In this case the said rods will generally only carry the weight for regulating the
stability of the compass within the gimbals.
In fluid compasses, the improved quadrantal corrector, with the described new curve
for the inner ends of the bars can also be applied in the horizontal plane of the
compass card but in this case it is required to add to the system a corrector adapted to
paralyse the disturbing effects of the iron bars produced by the vibrating motions of
the gimbal rings. This corrector consists of a magnet which is placed vertically
adjustable in a vertical tube fixed at the bottom of the apparatus centrally beneath the
compass card, either in combination with the device for the semicircular compensation
or with the metal rods which only carry the stability weight. This vertical magnet
would also be required for the same purpose if the improved quadrantal corrector were
applied in the horizontal plane of ordinary compass cards, instead of below them.
Lastly a corrector of healing error is provided, situated in the binnacle below the
centre of the compass, consisting of the well known vertical magnet rondered adjustable
for different distances from the centro of the compass.
The well known arrangement of "Flinder bars" may also be applied if desired.
Dated this 11th day of July 1888.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Ships' Compasses.
I, JOSEPH VON PEICHL of Fiume in the Austrian Empiro, Lieutenant of the
Imperial Austro Hungarian Navy, and Director of the Hungarian Sea Navigation
Company Limited 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 Specification to Patent No. 3738 of 1878 (being a communication to
C. D. Abel from me) I described a construction of ship's compass with an arrange-
ment of intensity multiplier and quadrantal "corrector" more particularly described
with reference to Figs. 5, and 6 of the respective drawings, which device consisted
of two discs S¹ S carrying iron bars in such a manner that the lower sides of the bars
of the upper disc were situated somewhat above, and the upper sides of the bars of
the lower disc somewhat below the horizontal plane of the compass card, or in other
words the mean horizontal plane of the double system of iron bars forming the
intensity multiplier and quadrantal corrector was made to coincide with the horizontal
plane of the compass card, such plane' being that passing through the geometrical
longitudinal axis of the compass needles.
The bars of both discs were mounted in a precisely similar manner, the bars being
of equal thickness but of such varying lengths, that while the outer ends thereof all
lie in a circle, the inner ends that are presented to the compass card all lie in an
ellipse, as shewn diagramatically at Fig. 2 annexed to this present specification.
The above described construction as also the mechanism described in the Specifica-
tion to Patent No. 3738 for adjusting the same for correcting quadrantal deviations D
and E, and the mechanism for correcting the semicircular deviations B and C have
been proved by experience to be opened to the following objections:
First. In consequence of the quadrantal corrector having been placed in the
horizontal plane of the compass card, the small space existing between the compass
needles and the inner ends of the iron bars prevented the use of large sized compass
cards, these being restricted to a diameter corresponding with the length of the
needles.

page_text: But at the present day compasses are largely used having cards of comparatively
large diameter with comparatively small needles, in order to increase the steadiness
of the card and to render the divisions of rhumbs and degrees more easily visible, so
that the said quadrantal corrector in the form described would be inapplicable to such
a construction of compass card, and if it could be so applied in the plane of the
compass card, it would render the compass of impracticably large dimensions.
Secondly. The said iron bars, in being inclined by the oscillating, motions of the
gimbal ring, would cause considerable vibrations of the compass card, the apparatus
described in the specification, offering no means for neutralizing suelt disturbing
effects of the bars.
Thirdly. Although the quadrantal corrector with elliptical arrangement of the iron
bars, as shown at Fig. 5 of the said drawings will compensate quadrantal deviations D
and E, yet it will at the same time produce an octantal deviation if the apparatus is to
be adapted for larger amounts of D. This octantal deviation, having around the
whole circle of the compass eight maxima alternating in their sign, has a prejudicial
effect on the shaping of a true course and renders it more difficult to adjust the
correctors for the deviations B, C, D, E. It also acts prejudicially on the construc
tion of correctors with very largo amounts of quadrantal forco (such as are now
required in conning towers, and for many steering compassos) the amount of octantal
doviation increasing with the amount of quadrantal force, which is augmented by
increasing the difference between the major axis and the minor axis of the ellipso in
which the inner ends of the bars lia, and can be reduced in this case only by a very
difficult process.
Fourthly: The said apparatus described with reference to Figs. 5 and 6 of the said
Specification, was not provided with any means for indicating the amounts of force
developed by the quadrantal corrector at different positions of the discs S¹ S around
the compass bowl, and also the correctors B and C. Fig. 6 of said specification, wero
not provided with scales of force for rendering it possible to readjust the correctors
independently of the direction of the ships head and of sights.
Fifthly. The said construction does not allow of ready access to the mechanism by.
which the quadrantal corrector is adjusted, and the mechanism as a whole requires to
be simplified and rendered of less weight.
My present invention relates to an improved construction of such compasses whereby
the above mentioned objections are obviated and whereby an improved type of
compass of comparativoly small size and sufficient power for any emergencies is
produced.
This improved compass which is shewn in plan at Fig. 4, and in section on yy, 2
by Figs. 5 and 6 of the accompanying drawings, is generally a fluid compass, but it
may be also any non fluid compass of sufficient stability for practical use. The
compass card has generally four neodles mounted by preference according to the
rules given in the Admiralty Manual for the deviations of compasses; but a greater
or less number than four needles may also be used.
In non fluid compasses I use by preference a card as shewn at Figs. 7 and 8.
This card is made of a larger diameter than would be necessary for the adopted
length of the needles f2, in order to render the division into rhumbs and degrees
more visible and for increasing the stability of the compass.
For this latter purpose the central part of the card is generally cut out and besides
I provide the card with a ring f' of unmagnetic material which is kept in a lowered
position under the card concentrically to by wires or columnes f* the latter ones
being fixed on the card.
The needles fare mounted on the card in a solid manner and the whole system is
carried by a cross f³ of thin wire mounted on the card and carrying in its centre the
cap containing the agate or some other stone.
This card is placed in the upper part a of the bowl, which is made wider than the
lower part al (Fig. 6) and the improved quadrantal corrector is, according to the
resent invention, placed around such lower part below the horizontal plane of the
.

page_text: card, being made rotatable concentrically round the part al and parallel to the horizontal
plane.
In the fluid compass, the card is generally made of a size corresponding more to
the length of the needles, and mounted with a floating arrangement f1 Fig. 6 for
reducing the friction on the pivot to a minimum. But any other type of floater may
he used instead of f¹ which has been chosen for the purpose only to shew the applica-
tion of Mr. Gareis' device for changing the pivot f³ by means of a key to be
applied at aº.
The improved quadrantal corrector consists of a double system of small bars c c¹ of
soft iron mounted upon two discs c² c³ and laid around the part a¹ as already stated,
the said discs being rendered independent by the gimbal ring e of the rolling and
pitching motions of the ship. These discs are rendered rotatable relatively to each
other by means of a gearing consisting simply of a toothed pinion ¹ which is situated
between two segments 2, 3 fixed respectively on the upper and lower disc. The
pinion can be turned by a key applied at h for adjusting the discs without having to
open the part of the binnacle containing the compass. A clamping scrow ³ retains
the two discs in position. Each disc carries by preference 32 iron bars; but a greater
For a less number can be used on both or either disc. In consequence of the discs
being situated below the horizontal plane of the card, the attracting action and
reaction between the compass needles and the iron hars c, c¹ does not take place in
a horizontal direction, but generally in a direction inclined to the horizontal at an
angle of about 45°. With this arrangement it is evident that if the two sets of bars
were made of equal form and size the upper set of bars would exercise a greater
influence upon the needles than the lower set. I consequently make the upper hars
of a less transverse section and, if necessary also of a less length, so as to increase
their distance from the needles, whereby the effect of both set of bars can be rendered
equal.
The arrangement of the bars, which is otherwise equal in both sets, is shown
diagrammatically at Fig. 3, according to which the bars of soft iron of each one of
the discs are arranged symmetrically with respect to the cardinal points A. B. CD
and radially around the centre which is supposed to lie in the perpendicular axis of the
compass bowl passing through the centre of the compass card.
The outer ends of the bars are generally arranged in a circle concentric to the
centre, while the lengths of the bars are so regulated that their inner ends lie in a
curve of the type A. E. OF BHD G. This curve, which is an essential feature of
my present invention, deviates from the ellipse due to the same axes A. B. and C D in
such a manner, that the bars situated near E F G H are longer than in the case of
the elliptical arrangement. The great and important object of this new curvo, which
compared to an ellipse shews in itself an octantal character, is to compensate, in
addition to the quadrantal deviations D and E, tho octantal error caused by the elliptical
arrangement of the bars Fig. 2 as also by an arrangement as at Fig. 1, and by
G. B. Airy's corrector of quadrantal deviations, in other systems of compensation.
In addition, the mean directive force of the compass is increased in an analogous
manner to that with elliptically arranged bars.
Owing to the circumstance that the development of quadrantal force in any such
system of induction bars, depends almost entirely upon the reciprocal action between
the inner ends of these bars and the compass needles, the arrangement of these inner
ends forms a most essential part of such an instrument. The above described octantal
curve forms the basis for the size, type and qualities of a compass provided with such
a compensation, and the application of this curve has alone rendered it possible to
place the discs with the bars below the horizontal plane of the card, without interference
of considerable octantal errors..
:
The extent to which the bars at the parts E F G H of the octantal curve have to be
lengthened is a matter ascertainable by experiment. Generally the greater the
occentricity of the ellipso the more doos the octantal curve doviato from the true
ollipso,

page_text: In some cases a single set of the above described bars may be used either in the
horizontal plane of the card, or below this plane for compensating approximately a
given amount of quadrantal deviation and increasing the directive force of the com-
pass, in which case the main axis A B would require to be placed, parallel to the
direction of the keel.
The lowered position of the bars, has, in addition to the before mentioned advantages,
the further advantage of reducing the disturbances of the compass needles, eventually
caused by more considerable vibrations of the whole apparatus within the gimbal ring;
the reduction being effected to such a degree, that it is unnecessary to employ means
to paralyse them; besides, the stability of the apparatus within the gimbal is
increased thereby, so that the necessary stability can be obtained with less total
weight of the instrument.
According to a further improvement, I apply to the quadrantal corrector a
scale J situated upon the upper side of the upper disc, while an index J pro-·
jects up from the lower disc over this scale so as to shew the relative positions
to which the two discs are adjusted and the proportionate force of the corrector,
duo to any position between that of maximum and that of zero.
The maximum of quadrantal force is developed if the main axis A. B Fig. 3
of both discs is parallel to the lubber lino y y Fig. 4, which is considered to bo
generally also the direction of the keel. This position is marked by 10 on the
scale J
In shifting the discs from this position by turning the gear at h, the long axis
of the one disc is deflected to the one side and that of the other to the other side
of the direction y y forming together an angle which is bisected by yy. The
quadrantal force developed by such deflections being proportional to the natural
cosine of the angle formed, is indicated by the scale J₁ in decimals of this, unit
down to zero.
can be
It is easily to be understood, that the improved quadrantal corrector
adjusted and readjusted by means of this scale without the employment of any
other means.
For the purpose of compensating with the improved corrector not only the
quadrantal deviation D, but also the oblique part thereof called E, the two discs
clamped together at are capable of being displaced from the direction of the
keel to an angle depending upon the relative values of tho doviations D and E it
one or two clamps k are released.
The amount of displacement is indicated in degrees on a scale ³ on the gimbal.
ringe by the index ..
It has been already mentioned that in some cases a single set of bars may be
used for correcting purposes. It may also be understood that a single set or a
double set of bars of equal form and size made rotatory round the upper part a
of the bowl like the duplex system underneath can be added to the latter system,
in order to impart to instruments of small diameter considerable directive and
quadrantal corrective force.
In this case I apply generally the upper set or sets of bars in the horizontal,
plane of the compass needles, leaving the lower duplex system in its position as
shewn at Fig. 6, and adapting the turning gear hi the scales J1 and 2 for the
adjustmont of both sets of bars.. If the upper duplex system is applied above the
horizontal plane of the needles, I make the bars of the lower set of a less transverse
section, and, if necessary, also of a less length, so as to render equal the effect of both
sets. The whole apparatus lies with its axis in the gimbal ring e the axis being
supported by antifriction rollers.
The gimbal ring lies with its axis e¹ e¹ in the bearings of the binnacle, the bearings
being situated in the athwartships direction.
The compass bowl is kept in its position by two brackets a³ mounted on its outside-
and fixed by two scrows d³ on the angles d³ carrying the instrument.
The bowl can be moved a little round the vertical axis on releasing the screws d', in

page_text: order to displace the lubber line, and thereby correct, if required, the constant
deviation A, the scale of which is situated at d³.
The two parts a a² of the compass bowl may be separate, the bowl a being inserted
in a' at a² so that it can be shifted round independently of the part a'.
Under the base plate d of the apparatus centrally under the compass card I fix
generally two perpendicular brass rods n carrying an adjustable weight m for regu
lating if necessary the stability of the instrument, and also two receptacles for small
magnets serving as correctors of the semicircular deviations B and C or parts thereof.
These receptacles are adjustable on the rods n which bear scales of force for indicating
the positions and the proportionate force of these magnets relatively to the compass
needles.
This arrangement of the correctors B and forms however no essential part of tho
improved apparatus, and these correctors might also he placed down in the binnacle as
in other systems of correctors.
In this latter case the rods a carry only the weight for regulating the stability of
the compass, or they may he dispensed with, and in order to be able to use the instru-
inent also in connection with old binnacles provided with correctors of the semicircular
doviation and of the healing orror, Ladapt the dimensions of the instrument to the
general size of such binnacles, saving thus the expense of a new binnacle.
The improved quadrantal corrector with tho octantal curve of the inner ends of tho
bars can also be applied in the horizontal plane of the compass card, but in this case I
add to the system generally a corrector adapted to paralyse the disturbing effects of
the iron bars produced by vibrating motions of the gimbal ring. This corrector
consists of a magnet which is placed vertically adjustable in the vertical tube p fixed.
at the bottom of the apparatus centrally beneath the compass card, either in combina-
tion with the device for the semicircular compensation or with the metal rods which
only carry the stability weight.
Besides the correctors of the coefficients A. B. C D E. described above, also the
well known arrangement of Flinder bar may be applied if required.
Lastly a corrector of the heeling error is provided, situated in the binnacle below
the centre of the compass, consisting of the well known vertical magnet rendered
adjustable for different values of this error.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what. I
claim is :-
1. In combination with a ships compass tho quadrantal corrector having bars of soft
iron arranged with their inner ends in an octantal curve such as A. C. CF. BH DC.
Fig. 3. substantially as and for the purpose sot forth.
2. In applying the improved double system of iron bars below the horizontal plane
of the compass needles, making the upper bars of less transverse section or longth
than the lower bars substantially as described.
3. The use of the duplex system of bars arranged as in Fig. 3 but of equal trans-
verse section and length in the horizontal plane of the compass needles.
Datod this 1st day of March 1889.
ABEL & IMRAY,
Agents for the Applicant.