Improvements in Mariners' Compasses.
Year: 1892

page_text: Date of Application, 28th June, 1892-Accepted, 3rd Sept., 1892
COMPLETE SPECIFICATION.
Improvements in Mariners' Compasses.
I, ROBERT OLIVER of No. 284, Warren Street, Brooklyn in the County of
Kings and State of New York, United States of America, Nautical Instrument
Maker and Compass Adjuster, 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:-
My invention relates to mariner's compasses, the purpose thereof being to
provide a liquid compass in which the polar force is distributed over the face of
the card by independent, parallel, magnetized needles, secured to the card in a
novel manner and having their terminals in the peripheral line, whereby the
polar attraction is more nearly equalized upon all sides of the pivotal support.
It is my further object to provide a compass having a bowl formed in one piece
of metal and provided with an expansion chamber beneath the bowl.
It is my further purpose to provide a mariner's compass having the compass
card provided with a plurality of needles having novel mounting, and provided
with an attachable and detachable ring air-chamber, in combination with a bowl
having an expansion chamber beneath, the card being centred by a suitable bearing
and sustained by an oil of a suitable color, whereby the rusting of the needles is
prevented.
It is an important feature of my invention that I seek to obtain such a
distribution of magnetic force, or polar attraction that, instead of being centred
at two points, or foci, as in the two-needle compass, it shall be scattered over all
the many points in which polar attraction may locate, being apportioned in sub-
stantial uniformity to each point, by which construction the compass shows less
error. It is my object also, to add to the sensitiveness of the compass-card, by
extending the multiple points of location of polar attraction, in parallelism upon
each side of the polar axis, fully as far as the edge of the card and arranging the
same directly upon the compass-card or substantially so, whereby I largely increase
the directive force, or, in other words, obtain a compass which is more constantly
upon the magnetic meridian. I also aim to avoid the presence of a species of magnetic
fulcrum, which is often found in compasses, whereby the magnetic pull, or push,
will create larger errors than are possible with a compass manufactured in accordance
with my invention.
My invention also comprises certain novel features of construction and new
combinations of parts, all of which will be fully set forth hereinafter, and then
specifically pointed out in the claims following this Specification.
To enable others skilled in the art to make, construct and use my said invention
I will describe the same in detail, reference being had to the accompanying drawing,
in which :-
Figure 1, is a plan view of a compass showing my invention.
Fi
Figure 2, is a central vertical section of the same.
Figure 3 is a bottom plan view of the compass card removed from the bowl.
In the said drawing the reference numeral 1, indicates the compass bowl, which
is circular in plan view, and having in its upper and larger portion a bowl 2, of
suitable depth to contain a body of oil to give flotation to the card in such degree
as to require from the central pivotal bearing merely the function of centreing
the card in the bowl, the weight sustained being only sufficient to ensure
maintenance of pivotal engagement between a central needle-pivot 3 in the bowl,
which enters a central cap 4, on the card and rests in an agate bearing 5, which is
detachable.
The body of the compass, below the bowl, is contracted in radial dimensions, to

page_text: provide a chamber 6 beneath the bowl but having its circular wall integral with the
other parts described. The expansion chamber is separated from the bowl by a
septum, or diaphragm 7, which forms the bottom of the bowl and is provided with
a series of openings 8, suitably arranged in its central portion. One of these
openings is in the bowl-centre, to receive the pivot bearing 3. The bowl is formed
of brass or other suitable metal, or material, and the lower part of the body is
formed in a separate part 9, attachable by screws enclosing the bottom of the
expansion chamber 6 and forming a ballast weight for the compass-body. The
latter is supported in a ring 10, which is provided with the usual gimball
supports 12. The compass bowl 2 is closed above by a strong glass plate 13, laid
upon the circumferential edge 14 in which a surrounding channel 15 is provided
next the edge of the glass. In this channel a rubber or other gasket 16 is
laid. Upon this is placed the gasket-annulus 17 and screws 18 are passed
through openings in the annulus and into threaded openings in the circumferential
edge 14 thereby compressing the gasket in the channel 15 and making an air-tight
joint.
The compass-card is composed of a flat annulus 19 of suitable material such as
linen, having a hard paint surface. Its width is sufficient to allow the points and
proper indications, or markings, to be placed thereon.
Crossing the open interior space of the annulus of each side of the centre is a
bridge-piece 20 formed of brass or other suitable metal, in very thin strips, bent
longitudinally, to form two strips one lying at right-angles with the other. One of
these strips is laid flat against the under face of the card, to which its end portions
are attached by screws or in any other suitable manner. The bridge pieces being
parallel they will have their angular strips projecting at right angles to the face of
the card and through these angular strips holes are drilled at suitable intervals, to
receive the magnetized needles 21, which may be fastened by a small drop of soft
solder, or by any preferred means. The ends of these needles extend to the outer
periphery of the card, and the series of said needles extends over the whole card
space, from east to west, separated by uniform intervals. The extremes 22 of the
series, lying at the east and west extremes of the equatorial line are short, but
equal to each other, and upon each side of the line joining the polar extremes, I
provide a field of polar attraction which is substantially equal in force and
extent to the similar field upon the other side of said line the diminished length
of the extremes 22 being partly compensated by the greater radial distance from
the centre.
Over the needles is arranged an air-chamber 23, of annular form and attached to
the bridge-pieces by screws. This ring-shaped air chamber is of suitable dimensions
to contain a body of air sufficient to nearly float the compass card and raised above
the same far enough to locate the centre of gravity below the point of pivotal support.
The latter consists of a central cap 4 having an agate bearing 5 which receives the
central point rising from the bowl. The cap 4 is connected to two of the needles
one on each side of the polar diameter the fastening being by means of attachable
and detachable clamps 24.
The construction set forth affords great delicacy of oscillation upon the pivotal
centre and ensures a corresponding high degree of accuracy. The oil reduces the
vibrations of the needles and practically eliminates its axial movement, while the
nature of said liquid prevents the accumulation of rust on the needles and also
is free from excessive expansion and contraction by change of temperature.
The lower portion of the expansion chamber 6 is closed by a diaphragm 6*, which
preferably is slightly convex on its upper face, as shown in Figure 2 and its
marginal portion is bent to form an outer rim or flange 24* which lies closely
against the inner circular face of the flange which depends from the bottom of the
compass-bowl. Between the flange 24, and the bottom 6" of the expansion
chamber, a circumferential, elastic rim 25 is formed by carrying the metal a little
above the floor 6* and then bending it upon itself to form the outer rim or flange 24*.
The convexity of the floor and the elastic yield of these parts is such as to enable

page_text: the chamber 6 to adapt its capacity to all the changes produced by changes of
temperature etc. As the body of oil expands with a rise of temperature, the
floor 6*, of the expansion chamber yields slightly, and is put under such a degree
of elastic tension that, as contraction takes place, it will be restored to its original
position and in this manner there will be a constant compensation for variations by
which the volume or bulk of oil is increased or diminished, with the effect of keeping
the compass bowl always filled.
It will be understood that the air is wholly removed from the bowl and expansion.
chamber.
By separating the compass-bowl from the expansion-chamber, by means of the
diaphragm 7, having openings 8 for communication, I am able to remove a large
part or the whole volume of oil from the compass-bowl without detracting in any
respect from the results sought and with material benefit in obtaining a perfect
light upon the compass card, since the bowl, being so much shallower, the reflection
of light from the bottom is much greater. The disturbance of the oil in the bowl,
due to the oscillation of the vessels is less with a small than with a large body of
oil, and the creation of counter-currents is practically avoided.
In securing the cap 4 to the card, I usually insert screws through openings in the
flange of the cap said screws being tapped into the clamps 24, resting on the needles.
adjacent to the central support. This is the preferred construction.
It is essential in this class of 'compasses that the elastic yield of the bottom of
the expansion chamber be sufficient to compensate for the expansion and contraction.
of the fluid in the compass-bowl under extremes of temperature ranging from
freezing up to the heat of a tropical sun. If the yield is not ample in degree, the
pressure will be exerted upon the glass, which has frequently been broken thereby..
Moreover the construction must be such that the yielding element shall always.
recover itself when the expansion ceases and contraction sets in.
If the convex
bottom of the expansion chamber snaps into the opposite form, that is to say, if it
is pushed downward until its liquid containing face is concave, it is possible that it
may remain in that form, especially if a considerable force is required in order to
press the enclosing rim outward far enough to permit the bottom to spring back to
its normal position.
My invention makes ample provision for all these requirements. The elastic rim
surrounding the bottom and connected integrally with the outer, surrounding flange,
or rim, will readily spring outward and inward and as the bottom is pressed by the
oil the elastic yield is ample to accommodate even greater volume of fluid than that
driven into the expansion chamber by the maximum expansion met with. The
normal tendency of this elastic rim to return to its place also assists the elastic
bottom in resuming its normal form, and I am thus able to use lighter metal for
the bottom of said expansion-chamber, as part of the elasticity is located in the
rim 25.
If this rim was rigid and unyielding, the pressure upon the convex bottom of the
expansion-chamber would, when excessive spring the convex bottom outward and
as there would be no yield in the rim, the bottom would necessarily buckle and
part of its elasticity would be destroyed, besides the danger of rupturing the metal.
It would be very likely also, to so weaken the tendency of the bottom to resume its
position. that it would, after a few expansions, remain permanently in the expanded
position, unless external force was used to restore it.
My construction also greatly facilitates the repairing of the compass, as the
expansion chamber may be removed by simply detaching the ballast weight and
applying pressure by means of the screw plug closing the filling opening, by which
the flange 24 will be driven out of the flange on the bottom of the compass-bowl.
Having now particularly described and ascertained the nature of iny said
invention and in what manner the same is to be performed, I declare that what
I claim is :-
==
1. In a mariner's compass, a compass card consisting of a card-annulus bridge

page_text: pieces on opposite sides of its centre their ends upon the surface of the card and
magnetized needles passing through openings in angular strips forming part of said
bridge-pieces and extending at frequent intervals over and upon the surface of the
card, the terminals of said needles being substantially coincident with the periphery
of the card, substantially as described.
2. In a liquid compass the combination with a bowl of an expansion-chamber
with which the bowl communicates the expansion chamber having a bottom which
is convex upon its inner or liquid containing surface, said bottom having an integral
surrounding rim, which is bent over outwardly, upon itself, to form an outer rim or
flange, by which the bottom of the chamber is attached beneath the compass-bowl,
and to provide an elastic rim, between the outer rim or flange and the convex
bottom of the expansion-chamber which will yield outwardly when pressure is
applied to the convex face of the bottom of said expansion-chamber, substantially
as described.
3. In a mariner's compass, the combination with a card having a card-annulus of
a series of magnetized needles arranged in parallelism and supported in bridge
pieces extending on opposite sides of the equatorial centre a ring air chamber
mounted on said bridge pieces and a pivot bearing having a detachable agate seat
for the pin, substantially as described.
4. In a mariner's compass, a compass-card composed of a card-annulus magnetized
needles arranged in bridge pieces lying parallel with the equatorial line and having
angular strips provided with openings to receive the needles the latter having their
ends co-incident with the periphery of the card, a compass-bowl having a central
pivotal bearing entering a seat attachably and detachably mounted on the needles
of the card, and a body of juniper, or other oil, contained in the bowl substantially
as described.
5. In a mariner's compass, a closed compass-bowl having an expansion chamber
the bottom of which is convex on its upper face and provided with an elastic,
circumferential rim, uniting said bottom to an outer rim or flange by which said
bottom may be secured in position substantially as described.
6. In a mariner's compass, the combination with a compass-bowl of a com-
municating expansion chamber the bottom of which is slightly convex on its liquid
containing face, and provided with a circumferential rim or flange, between which
and the bottom of said chamber is an elastic rim rising above the floor and formed
by bending the metal upou itself to form the flange the circumferential rim, or
flange, being rigidly attached to a circular flange depending from the compass-bowl,
substantially as described.
7. In a mariner's compass, the combination with a card of a series of magnetized
needles arranged in parallelism and supported in bridge-pieces extending on
opposite sides of the equatorial centre, an attachable and detachable ring air-
chamber, mounted on said bridge pieces, and a pivot bearing having a detachable
agate seat, substantially as described.
Dated this 28th day of June 1892
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.