US478017A - Mariner s compass - Google Patents

Description

(No Model.)

R. OLIVER. MARINBRS COMPASS.

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` UNITED STAT-Es PATENT OFFicn.

ROBERT OLIVER, OF BROOKLYN, NEW YORK.

MARINYERSiCOM PASS.

SPECIFICATION forming part of Letters Patent No. 478,017, dated June 28, 1892.

Application filed March 7, 1892. Serial No. 424.047. (No model.)

To all whom it may concern/5 Be it known that I, ROBERT OLIVER, a subject ot the Queen of Great Britain, but having declared my intention of becoming a citizenof the United States, residing atBrooklyn, in the county of Kings and Stateof New York, have invented new and useful'lm provements in Mariners Compasses, of which the following is a specification. Y

My invention relates to mariners 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 magnet-ized 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 pieceY of metal and provided with an expansion-chamber beneath the bowl.

It is my further purpose to provide a mariners compass having the compass-card provided with a plurality of needles having novel mounting and providedY with an attachable and detachable ring air-chamber, in combination with a bowl having an eXpansion-chamber beneath, the card being centered 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 centered at two points or foci, as in thetwo-needle compass, it shall be scattered over all the many points in which polar attraction may locate, being apportioned in substantial 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 ofthe polaraxis fully as far as the edge of the card and arranging the same directly upon the compasscard, or substantially so, Wherebyl largely increase the directive force, or, in other words, obtain a compass which is more constantly upon the magnetic meridian. I also alm to avoid the presence ofv a species of magnetic fulcrum, which is often found in other 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 ofl which will be fully set forth hereinafter, and then specifically pointed out in the claims following this specification. a

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 drawings, inwhich- Figure l is a plan view of a compass, showing my invention. Fig. 2 is a central vertical section of the same.V Fig. 3 is a bottom plan view of the compass-card removed from the bowl.

In the said drawings the reference-numeral l indicates the compass-bowl, which is circular in plan View and having in its upper and larger portion la 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 centering the card in the bowl, the weight sustained being onlysuiiicient to insure 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 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 arrangedin its central portion. One of these openings is in the bowl-center 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 formedin a separate part 9, attachable by screws, inclosing the bottom of the expansion-chamber 6 and forming a ballast-weighty for the compass-body. The latter is supported in a ring 10, which is provided with the usual gimbal-supports 12. The compass-bowl 2 is closed above by a IOO 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 channela rubber or other gasket16 is laid. Upon this is placed the gasketannulus 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 1 9 of suitable material-such as linen-having a hard-paint surface. Its width is sufficient to allow the points and properindications or markings to be placed thereon. Crossing the open interior space of the annulus on each side of the centerisa 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 extend 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 otherside of said line,the diminished length of the extremes 22 being partly compensated by the greater radial distance from the center.

Over the needles is arranged an air-chamber 23 of annular form and attached to the bridge-pieces by screws. 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 center of gravity below the point of pivotal support. The latterconsists of a central cap 4, havin g 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 clasps 24.

Theconstruction setforth affords great delicacy of oscillation upon the pivotal center and insures a corresponding high degree of accuracy. The oil reduces the vibrations of the needles and practicallyeliminates its axial movement while the nature of said liquid prevents the accumulation of rust on the needles, and also is free from excessive ex- ',the central support. construction.

pansion and contraction by change of temperature.

The lower portion of the expansion-chamber 6 is closed by a diaphragm 6a, which preferably is slightly convex on its upper face, as shown in Fig. 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 alittle above the floor 6a and then bending it upon itself to form the outer rim or flange 24a.

The convexity of the floor and the elastic yield of these parts is such as to enable the chamber 6 to adapt its capacity to all the changes producedby changes of temperature, &c. As the body of oil expands with a rise of temperature, the floor 6a of the expansionchvamber yields slightly, and is put under such a degree of elastic tension that as contracphragm 7, having openings 8 for communication, I am able to remove a large part of the whole volume of oil from the compass-bowl ywithout detracting in any respect from the ,results sought and with material benefit in obtaining a perfect light upon the compasscard, since the bowl being so much shallower the reflection of light from the bottom i is much greater. The disturbance of the oil in the bowl, due to the oscillation of the vessel, is less with a small than with a large body ot' oil, and the creation of counter-currents is i practically avoided. This ring-shaped In securing the cap 4 to the card I usually insert screws through openings in the flange l of the cap, said screws being tapped into the clamps 24, resting on the needles adjacent to This is the preferred It is essential in this class of Compasses l 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 mustbe 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 oppo- IOO IIO

elasticity would be destroyed, besides the site form-that is to say, if it is pushed downward until itsliquid-containing face is con-V cave-it is possible that it may remain in that form, especially if a considerable force is required in order to press the inclosing 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 ork 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 volumes 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 locatedv in the rim 25. If this rim were rigid and unyielding, the pressure upon the convex bottom of the expansion-chamber would when excessive spring the convex bottom outward, andas there would be no yield in the rim the bottom would necessarily buckle, and part of its danger of rupturi ng 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 were 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 fillingopening, by which the flange 24 will be driven out of the iiange on the bottom of the compass-bowl.

lVhat I claim isl. In a mariners compass, a compass-card consisting of a card-annulus having bridgepieces on opposite sides of its center, their ends upon the surface of the card, and magnetized needles passing through openings in angular strips forming part of said bridgepieces and extending at suitable 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 expansionchamber having a bottom which is convex upon its inner or liquid-containing surface, said bottom having an integral surrounding rim `which is bent over outwardlyupon itself to form an outer rim or fiange, by which the bottom of the chamber is attached beneath the compass-bowl, and-to provide an elastic ring 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 mariners compass, the combination, with a card having a card-annulus, of a series of magnetized needles arranged in parnallelism and supported in bridge-pieces extending on opposite Vsides of the equatorial center, a ring air-'chamber mountedV on said bridge-pieces, and a pivot-bearing having a detachable agate seat for thepin, substantially as described.

4. In a mariners compass, a'compass-card composed of acard-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 coincident 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 mariners 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 fiange, by which said bottom may be secured in position, substantially as described.

6. In a mariners compass, the combination, with a compass-bowl, of a communicating expansion-chamber, the bottom of which is slightly convex on its lliquid -containing face and provided Witha circumferential rim or iiange, between which and the bottom of said chamber is an elastic rim rising above the floor and formed by bending the metal upon itself to form the'flange, the circumferential rim or flange being rigidly attached to a circular flange depending from the compassbowl, substantially as described.

7. In a mariners 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 center, an attachable and detachable ring air-chamber mounted on said bridge-pieces, and a pivot-bearing having a detachable agate seat, substantially as described.

In testimony whereof I have hereunto set my hand and affixed my seal in presence'of two subscribing witnesses. i

ROBERT. oLIvER. [n s] Vitnesses: Y GEO. W. HUNT, 4 DE-HART BERGEN, Jr.

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