Abstract: The balancing righting moments and dampening of the compass card and directive magnets in a liquid damped magnetic compass are separated to reduce the tilt and oscillation of the compass card when subjected to lateral acceleration, such as pitching and rolling in a seaway. The compass card is connected to the pivoted directive magnetic assembly by a card gimbal arrangement. The compass card is connected to the outer side of the gimbal ring rotating on a first axis. The magnetic assembly is connected to the inner side of the gimbal ring for rotation along a second axis oriented 90 degrees from the first axis.

Abstract: An underground localization method and a system therefor are provided. The underground localization method includes computing location information of a dead reckoning using a gyro sensor and a distance movement sensor of moving equipment, measuring physical information according to the computed location information of the dead reckoning and searching for the physical information which is determined as being matched with the location information of the dead reckoning, and optimizing a location by reflecting location information of the physical information which is determined as being matched with the location information of the dead reckoning.

Abstract: A compass includes a case, a first support shaft, a second support shaft, and a needle. The case includes an upper plate, a lower plate, and a side wall that connects edge portions of the upper plate and the lower plate. The first support shaft is coupled to the lower plate and protrudes toward the upper plate, and the second support shaft is coupled to the upper plate and protrudes toward the lower plate. The needle includes a support unit, a first indicator unit, and a second indicator unit. The support unit is disposed between the first support shaft and the second support shaft, and includes a first support groove that is formed close to the first support shaft and a second support groove that is formed close to the second support shaft. The first indicator unit is coupled to one side of the support unit, and the second indicator unit is coupled to the support unit to face the first indicator unit with the support unit therebetween.

Abstract: Low friction or nearly frictionless compasses are provided. One compass embodiment includes a housing having a wall forming a chamber, the housing having a closed end and an open end. The compass includes a fluid disposed within the chamber. The compass includes a magnetized material floating in the fluid, wherein the magnetized material is operative to indicate Earth's magnetic north. The compass includes a protective face adjacent to the open end, wherein the protective face closes the open end of the chamber. Also provided is a compass that includes low friction material deposited on at least one side of the magnetized material and the adjacent closed end of the housing to create a nearly frictionless interface.

Abstract: A magnetic compass is provided which features a stationary central pointer which extends outwards to the inside of a rim displaying graduated angular indicia, said rim being integral with a pivoting disc which is magnetically coupled. The central pointer assumes the graphic shape of a craft, such as a ship's hull, the stationary disposition of which offers a more intuitive realization of the directional heading of a vessel with respect to the cardinal axes of a compass.

Abstract: Low friction or nearly frictionless compasses are provided. One compass embodiment includes a housing having a wall forming a chamber, the housing having a closed end and an open end. The compass includes a fluid disposed within the chamber. The compass includes a magnetized material floating in the fluid, wherein the magnetized material is operative to indicate Earth's magnetic north. The compass includes a protective face adjacent to the open end, wherein the protective face closes the open end of the chamber. Also provided is a compass that includes low friction material deposited on at least one side of the magnetized material and the adjacent closed end of the housing to create a nearly frictionless interface.

Abstract: A magnetic compass is provided which features a stationary central pointer which extends outwards to the inside of a rim displaying graduated angular indicia, said rim being integral with a pivoting disc which is magnetically coupled. The central pointer assumes the graphic shape of a craft, such as a ship's hull, the stationary disposition of which offers a more intuitive realisation of the directional heading of a vessel with respect to the cardinal axes of a compass.

Abstract: A ball cavity cube vial comprising a cube made of an at least translucent material, and having a sealed ball cavity in its center, said ball cavity being incompletely filled with a liquid medium such that a bubble is left inside of said ball cavity; and markings associated with said cube, said markings being calibrated to function as reference points for said bubble.

Abstract: The invention relates to an integral magnetic compass for obtaining deviations in real time, formed by a transparent sphere or cylinder (2), incorporating therein, in a hydrocarbon liquid (3), a polyester or silicon disk (4) to which the rose (5) and the magnet (6) are fitted, being associated with a commutation system formed by integrated software in a device or chip (7), the circuit of which has two inputs: an input (8) to the signal obtained from the magnetic compass (1) itself, obtained by means of a magnetometer (9) or optical reader (10) in association therewith, and another input (11) to the signal from the satellite compass (12) or from the gyroscopic compass (13), and said circuit having an output (14) to a display (15) for viewing and storage of the data for the corresponding deviations, thus obtaining the deviation chart for the magnetic needle in real time, said output being also applicable to the automatic pilot (16).

Abstract: A recreational or outdoor compass is comprised of a base member and a vial assembly pivotally coupled to said base member. The vial assembly comprises a vial with an orienting marker and a magnetized indicator member journaled in the vial and pointing to magnetic north, the indicator member having through hole. The orienting marker has an outer contour, wherein the shape of the outer contour of the orienting marker essentially corresponds to the shape of the inner contour of the through hole, such that the outer contour of the orienting marker virtually matches the inner contour of the through hole when pointing northwards.

Abstract: A combination name badge and compass includes a substantially planar substrate having a front surface that has name indicia thereon, and a rear surface and a clutch bar that includes spaced pins. The clutch bar is secured to the rear surface of the planar substrate with the pins extending away from the planar substrate. A magnetic circuit includes a pair of opposite polarity magnets mounted at the substrate. The magnetic circuit further includes a metal arrow that is coupled with the opposite polarity magnets to form the magnetic circuit. When the name badge is floated on a liquid surface the metal indicator points to magnetic north.

Abstract: The invention relates to an integral magnetic compass for obtaining deviations in real time, formed by a transparent sphere or cylinder (2), incorporating therein, in a hydrocarbon liquid (3), a polyester or silicon disk (4) to which the rose (5) and the magnet (6) are fitted, being associated with a commutation system formed by integrated software in a device or chip (7), the circuit of which has two inputs: an input (8) to the signal obtained from the magnetic compass (1) itself, obtained by means of a magnetometer (9) or optical reader (10) in association therewith, and another input (11) to the signal from the satellite compass (12) or from the gyroscopic compass (13), and said circuit having an output (14) to a display (15) for viewing and storage of the data for the corresponding deviations, thus obtaining the deviation chart for the magnetic needle in real time, said output being also applicable to the automatic pilot (16).

Abstract: An apparatus for aligning a trailer hitch and receiver includes an elongated channel or tube defining an angle, such that when the trailer is tilted back for hitching, the upper tube is substantially vertically aligned. A rubber tipped rod extends from the lower tube and contacts the vehicle when the vehicle draws near the trailer. As the rod is pushed into the lower tube, a connecting rod drives an actuator or indicating rod upwards. A calibration tube is slid over the upper tube, and is aligned along the upper tube to expose a brightly colored painted region on the indicating rod at the point where the receiver and hitch are aligned one above the other. Alternatively, the calibration tube moves a series of switches up or down, whereby the actuator is pushed by the rod to contact the switches successively to indicate the approach to and arrival at a hitching position, by the illumination of electric lights, and or by activation of an audible signal.

Abstract: A simple self-contained, hand-held instrument for reading an azimuth or bearing in relation to the earth's magnetic field either out in the field or on the water with substantial accuracy. Means are provided that places the far object into the same focal plane (or focal point) as the close up bearings on the compass disc face, thus allowing the eye to instantly see both images without adjustment between near-sight and far-sight. Means are also provided for the adjustment of the instrument for the local variation or declination of the earth's magnetic field versus that of true north.

Abstract: A self-balancing, no-spin magnetic compass. A described embodiment includes a compass card assembly, a retainer assembly, a pivot assembly, a gimbal assembly, a cup, and a dome. The compass card assembly includes an air chamber which provides buoyancy. The retainer assembly functions with the compass card assembly to retain magnets. The pivot assembly snap-fits into the retaining assembly and contacts the compass card assembly to allow the compass card assembly to pivot about the pivot assembly. The pivot assembly also snap-fits into the gimbal assembly. The base of the pivot assembly is positioned into the cup and the entire compass is secured into the dome, that is filled with a fluid.

Abstract: My invention, a fluid instrument bearing, which in one embodiment is constructed in the form of a magnetic compass, negates or greatly reduces the defects of the prior art by allowing the pole seeking magnet or magnets and associated indicia complete freedom of motion about all axes simultaneously, and by greatly reducing the pendulous effects of the prior art. At the same time, my invention is easy to construct and requires no frictional parts such as bearings. While this disclosure treats in its exemplary embodiment with the construction of a magnetic compass, it is to be understood that this invention deals with an essentially frictionless bearing or gimbal having complete freedom of motion about all axes simultaneously and as such is not limited only to its use in magnetic compasses, but will be of value whenever its unique properties and characteristics may be applicable.

Abstract: An Improvement to enhance the usability of magnetic compasses by eliminating acceleration and turning errors, especially in aviation applications, without compromising simplicity and reliability. The improvement includes the addition of a weightless mass to the bar magnet of a conventional magnetic compass to counteract undesirable inertial forces on the bar magnet.

Abstract: A self-balancing marine compass. A described embodiment includes a pivot assembly, a buoyant-magnetic chamber assembly, a reading card assembly, and a dome. The pivot assembly includes fulcrums, each of which fit within fulcrum holders located on an inner surface of the reading card assembly. The buoyant-magnetic chamber assembly is positively buoyant within the dome and includes pivots meeting with pivot axes of the fulcrum holders. This embodiment is also a no spin compass.

Abstract: A marine compass module can be selectively mounted in either a U-shaped bracket or a binnacle, and all of these items can be marketed in the same package. The compass module can be adjusted so that its magnetic card is horizontally aligned even though the compass is mounted on a non-horizontal surface of a marine vessel. The magnetic adjusting rods are contained in the compass module itself instead of being in the mounting hardware.

Abstract: A low profile compass of the type including a transparent base member and fluid-filled vial contains a directional indicator in the vial in the form of a circle which is alignable with another circle imprinted on the vial. A hinged cover assembly can be detented to selected positions and includes a mirrored sight line for direct line sighting, and a lower protective cover or shoe for the base of the compass also serves as a receptacle for instruction sheets and scales for use in taking directional readings as well as for orientation alignment on a topographic map and inclinometer readings.

Abstract: The present invention provides a compass comprising an at-least-partially-transparent housing having a top and a bottom, a vertically orientated, conical pivot bearing, and a magnetic detection means which is mounted on the vertically-oriented conical pivot bearing. The magnetic detection means thereby is capable of rotating in a substantially-horizontal plane. The magnetic field detection means is provided with a radially-extending, tilt-compensating, indicator device. The indicator device has at least one spacer element which is spaced from the magnetic field detection means, the spacer element projecting from the indicator device and being directed towards one of a top of the housing of the compass and a bottom of the housing of the compass.

Abstract: A gimballed compass apparatus with digital logic is disclosed which provides directional and attitudinal data. The apparatus comprises a rotatably mounted slotted disk wherein the slot is continuously varying in width around the circumference of the disk. The disk incorporates an elongated magnet which cause it to rotate in relation to an external magnetic field. A first and second aperture are located on the top and bottom elements of the chamber defining a light passage. The apertures have a rectangular length approximately the maximum width of the slot. The slotted disk is positioned intermediate the apertures. A light housing is provided below the chamber and includes a light source. A linear array of source detector are provided above the chamber. Each source detector element provides a response proportional to the specific amount of light incident upon it. The light beam is reflected from the aperture by a mirror to a beam focusing device.

Abstract: A navigational device that employs the azimuthal position of a housing assembly relative to the Earth's magnetic field to alter light such that the altered light becomes a direction indicator. By using the altered light as a signal the device is both economical and reliable.

Abstract: An adjustable magnetic compass for adjustably compensating for the magnetic variation between magnetic north and map north. The adjustable compass includes a compass dial having directional indicia applied thereto, and a lubber line for operative alignment relative to the directional indicia. The lubber line can be rotatably adjusted relative to the directional indicia so as to visually compensate for the magnetic variation between magnetic north and map north with respect to the geographic location in which the adjustable magnetic compass is to be located.

Abstract: A real time directional orientation apparatus is disclosed for use in a four pi (4.pi.) geometry. The apparatus is to be affixed to an object which translates in space. A source emitter means, which may be radioactive, is suspended in a fluid in concert with a magnet. A bank of emission detectors registers the orientation of the source emitter or emitters against a known starting value. As the object translates in space, so does its position and orientation, thus causing the magnet to adjust its position in reference to an external magnetic field, such as, but not limited to, the earth's magnetic field. The motion of the magnet causes the emitter or emitters orientation to change which is sensed by the emission detectors as both a change in intensity and position. This data is processed by a computer and with ancillary data provided by other sensors provides real time position, path and other navigational, directional and positional data, such as pitch, yaw, attitude and roll.

Abstract: A real time directional orientation apparatus is disclosed for use in a two pi (2.pi.) geometry. The apparatus is to be affixed to an object which translates in space. A cylindrical disk is suspended in a fluid in concert with a magnet. The cylindrical disk is disposed inside a cylindrical housing. A light source is in communication with the disk and the light is propagated through the disk where it is finally projected from the disk in a radial fashion. The light beam projected is detected by a bank of photon sensitive detectors lining the interior of the cylindrical housing. The light source is propagated through two coplanar, orthogonal light channels which emanate from the center of the disk in a radial fashion. The photon sensitive detectors register the orientation of the light channels against a known starting value.

Abstract: A gimballed compass apparatus is disclosed which provides directional and inclinational data. The apparatus comprises a rotatably mounted slotted disk wherein the slot is continuously varying in width around the circumference of the disk. The disk incorporates an elongated magnet which causes it to rotate in relation to an external magnetic field. A first and second aperture are located on the top and bottom elements of the chamber defining a emission passage. The apertures have a rectangular length approximately the maximum width of the slot. The slotted disk is positioned intermediate the apertures. An emission housing is provided below the chamber and includes an emission source and a first source detector. A second source detector is provided above the chamber. The source detectors provide a response to the intensity of emission incident upon them.

Abstract: A method of preventing air bubbles in a compass equipped with fluid expansion capability, wherein a compass unit is assembled with a fluid expansion diaphragm; the compass unit is filled with fluid expanding the diaphragm, and sealed while maintaining the diaphragm in its expanded state for preventing air bubbles in reduced pressure and/or reduced temperature conditions, without significantly changing the basic structure of the compass.

Abstract: A low cost, simple apparatus is disclosed which can be used to provide positional information relative to an external magnetic field. The apparatus comprises a rotatably mounted slotted disk wherein the slot is continuously varying in width around the circumference of the disk. The disk incorporates an elongated magnet which causes it to rotate in relation to an external magnetic field. The slotted disk is placed in a fluid filled chamber. A first and second aperture are located on the top and bottom elements of the chamber defining an emission passage. The apertures have a rectangular length approximately the maximum width of the slot. The slotted disk is intermediate the apertures. A source detector is provided below the chamber proximal an emission source, and a second source detector is provided above the chamber. The source detectors provide a response to the intensity of emission incident upon them.

Abstract: An optical sighting instrument having a main optical path including an objective lens, an eyepiece lens and a beamsplitter for combining or superimposing images. At least three image planes are defined with reference to the main optical path and the beamsplitter, and at least one of the three image planes is optically superimposed with the other two by the combining effect of the beamsplitter. Movable indicia elements are positioned in two of the image planes, and a fixed indicia element is positioned in the third one of the image planes. As a result, images of all three of the indicia elements are superimposed for viewing through the eyepiece lens, and the image of the fixed indicia element serves as a sighting reference. Illustratively, one of the movable indicia elements is a magnetic compass, the other of the movable indicia elements is a magnetic declination adjustment, and the fixed indicia element is a cross-hair sight.

Abstract: The improvement of the present invention provides a camper's compass having a plate or member, such as an arcuate bow, having a direction pointer, which is pivotably mounted over the compass housing in such as way that it can swing between a normal forward position in which the compass is oriented in the desired direction of travel, and a diametrically opposed or reverse position. By pivoting the arcuate bow or member from its forward position to its reverse position, the user can set the return direction to the point of departure on the compass. The direction of a reverse path back to his point of departure is readily determined without making any mathematical calculations or trying to use the orienting means of the compass in reverse positions. This simplified manner of setting a return path on the compass eliminates confusion which otherwise may occur and result in disorientation of a user in his attempt to return to his point of origin.

Abstract: A magnetic compass has an instrument body adapted to be held level by a gimbal mechanism and having a vertical cylinder member, a spherical or semi-spherical float body on the upper end of the cylinder member and having a spherical surface facing downwardly into the upper end of the cylinder member, a magnet at a bottom center of the float body for making the center of gravity of the float body near the bottom center of the float body, a graduated azimuth scale on the float body, a lubber's line indicator on the surface of the instrument body surrounding the float body, and an air blowing device operatively associated with the cylinder member for blowing rectified air upward through the inside of the cylinder member with a force sufficient for making the float body float stably on the upper end of the cylinder member and out of contact therewith for enabling the float body to freely turn in response to geomagnetic force.

Abstract: A liquid-type compass comprises a light-weight thin, flat disk of magnetic material so constructed that it is capable of floating on a liquid surface so as to be movable to orient itself in a North-South direction. A flat support provided for storing the disk when not in use is releasably secured to a support member. The support member is in the form of a small flat card containing survival instructions as well as instructions for use of the compass.

Abstract: A magnetic compass in which a conventional compass card provides an analog readout of compass heading and a binary coded digital disk together with fiber optic sensing technology provides a digital readout of compass heading contained within a single housing, together with a gravity driven inclinometer providing a measurement of the inclination of the ground. The compass magnet is shielded by Faraday type shielding from the electronics that processes the digital reading. An analog electronic readout of both compass heading or inclination, capable of remote display, is provided by a tapered iris disk and fiber optic reader combination. A magnetic compass employing a compass disk with a reflecting tapered iris on one side of the disk sensed by a reflecting fiber optic reader and a standard compass card on the other side which can be read visually provides an improved magnetic compass being very compact and providing both analog and digital readouts.

Abstract: The invention relates to a mask compass comprising a case attached to the outer surface of glass of goggles. The compass box is placed inside the casing. Thus the checking of the compass does not interfere with regular diving movements and e.g. cause deviations from the right direction.

Abstract: An improved magnetic compass unit consists of a compass bowl, a card assembly pivotally supported on a pivot shaft within the bowl, the card assembly consisting of a compass card and a magnet, and at least one active indicator pin adapted for alignment with the lubber line of a supporting vehicle and with an adjacent degree indicia line upon the compass card. The active indicator pin is mounted to pivot apart from the pivotally mounted compass assembly, whereby the indicator pin remains disposed generally in a common plane with the adjacent degree indicia line during conditions of compass roll. The card assembly may be with or without gimbal mounting.

Abstract: A compass assembly comprising a base, a dial member received in a recessed portion of the base and rotatable relative the base about a dial member central longitudinal axis, and a compass housing received in a recessed portion of the dial member and fixedly secured to the base by a connecting disk. The disk has a first surface attached to the housing and a second surface attached to the base and a peripheral edge surface positioned in frictionally engaging contact with the dial member. The dial member is biased against rotation relative the base and the compass housing by the disk.

Abstract: A magnetic tile sensor has a permanent magnet having a surface coated with a magnetic fluid and housed in a hollow portion of a nonmagnetic case, and a magnetic sensing element arranged outside the bottom portion of the case. When the case is tilted or is abruptly moved, the permanent magnet in the case is relatively displaced. The magnetic sensing element detects this displacement. Since the nonmagnetic case is sealed by a cold welding method, workability and reliability can be increased. In addition, a cap having a predetermined weight covers the permanent magnet so that a response characteristic is improved.

Abstract: A unit comprising a base on which is mounted an atlas of maps each with an arrow thereon indicating the relation of the map area to north, and on which base is also mounted a compass having in a container a liquid on which floats a magnet bearing disk on the surface of which disk is a visible pointer pointing in the direction of the magnet's north pole and the earth's magnetic pole. A ball of non-permanent magnetic material centered on a cover of the container cooperates with the magnet in maintaining the floating disk centered in the container and spaced below the ball. In use, the unit is turnable by the traveler until the arrow on the map points in the same direction as the pointer on the disk, thereby apprising the traveler as to his position relative to his surroundings.

Abstract: There is proposed a tilt sensor in which a first permanent magnet having a magnetic fluid adhered to its surface is housed in a nonmagnetic case, a magnetic sensing element is arranged outside a bottom portion of the case, and a second permanent magnet is arranged so as to surround the magnetic sensing element and have polarity directions opposite to those of the first permanent magnet. When the case is tilted at an angle larger than a predetermined angle, the first permanent magnet is instantaneously moved, and the magnet sensing element detects changes in magnetism, thereby detecting a tilt of the case.

Abstract: There is proposed a tilt sensor in which a permanent magnet having a surface coated with a magnetic field is housed in a hollow portion of a nonmagnetic case, and a magnetic sensing element is disposed outside a bottom portion of the case. When the case is tilted at an angle exceeding a predetermined angle, the permanent magnet is greatly moved and the magnetic sensing element detects the movement of the magnet. Furthermore, adverse influences due to magnetic attraction between the permanent magnet and the magnetic sensing element or a surface tension of the magnetic fluid are compensated.

Abstract: A magnetic compass having a magnet bearing float in a liquid and which float is self-centering and rotatable relative to an element of soft magnetic material spaced below it so as to align a pointer on the float with the earth's north magnetic pole and with the north point of a compass readout dial.

Abstract: A magnetic tilt sensor in which a permanent magnet having a surface coated with a magnetic fluid is housed in a space inside a nonmagnetic case and is freely movable, and a magnetic sensing element is disposed to oppose the space through the case. When the case is tilted, the permanent magnet inside the space is moved to a lower position, and hence magnetism detected by the magnetic sensing element changes, thereby detecting a tilt of the case.

Abstract: There is provided an optical viewing system, which is preferably a compass which eliminates the parallax and sighting problems of prior art optical systems. The compass includes a beam splitter which displays a sighted image both on a reference screen and a free-floating magnetized sphere or other moving surface. The sighted image on the reference screen and on the sphere are superimposed upon each other when viewed through one facet of the beam splitter. In this manner parallax is eliminated, thus the direction and elevation of the image may be readily and accurately determined.

Abstract: A housing defines a chamber having a spherical inside surface, and a spherical float is supported within the chamber by a liquid so that the outside surface of the float is equidistantly spaced from the top and bottom of the inside surface of the chamber. The float incorporates a permanent magnet defining diametrically-opposed opposite poles which serve to orient the float with respect to the earth's magnetic field. The liquid is magnetizable, and the float is laterally centered within the chamber by magnetic interaction between the magnet poles and the magnetizable liquid. A differential fluxgate sensing head serves to sense the relative orientation of the housing and the float in a horizontal plane and to supply an electrical output signal indicative of that orientation. A highly accurate direction-finding device is thereby produced at modest cost.

Abstract: A vibrator attenuator, especially for a compass. The vibration attenuator is situated to prevent transfer of vibrations from the fastening base of a compass, e.g. from the framework of a boat, to the compass rose, to prevent revolving of the compass rose that results from such vibrations, and to prevent transfer of external impacts to the compass rose itself. The vibration attenuator is disposed between a supporting rod of a bearing of the compass rose, and a frame of the compass, so as to resiliently interconnect the supporting rod and frame. The vibration attenuator is preferably attached to a supporting bridge in turn affixed to the compass frame. The vibration attenuator may be an elastic member or a spring, which is attached to the supporting rod and to the supporting bridge, so that the vibration attenuator is resilient in both a vertical or longitudinal direction, and in a lateral or horizontal direction.

Abstract: A remotely readable fiber optic compass. A sheet polarizer is affixed to a magnet rotatably mounted in a compass body, such that the polarizer rotates with the magnet. The optical axis of the sheet polarizer is preferably aligned with the north-south axis of the magnet. A single excitation light beam is divided into four identical beams, two of which are passed through the sheet polarizer and through two fixed polarizing sheets which have their optical axes at right angles to one another. The angle of the compass magnet with respect to a fixed axis of the compass body can be determined by measuring the ratio of the intensities of the two light beams. The remaining ambiguity as to which of the four possible quadrants the magnet is pointing to is resolved by the second pair of light beams, which are passed through the sheet polarizer at positions which are transected by two semicircular opaque strips formed on the sheet polarizer.

Abstract: This invention relates to a wind direction indicator spherically rotatable about a liquid supported poly axial magnetic compass. The wind direction indicator determines the wind direction without any pivotal support. The wind direction structure is orientated to the reference center of the compass by means of the transparency of the spherically rotating structure. The displacement of the wind direction indicator base upon the wind responsive rudder and wing structure thereon causes the device to give an accurate direction of the wind that may be used during sailboat racing. The spherically rotatable structure or wind direction indicator is independently movable regardless of the mounting of the device on the sailboat or any other support structure. The frictional contact between the boat support structure and the device is minimized because there is no surface to surface contact between the moving elements.

Abstract: This invention sets forth a wind tracking device particularly useful on sailing vessels for determining the best sailing direction relative to the wind. The reference card is provided with color panels which cooperate with lines on the dome to indicate best direction. Further, the card has circular lines about the axis which cooperate with a dot on the axis of the dome to indicate a 360.degree. level condition around a horizontal plane.

Abstract: A cylindrical compass gimballing and data readout system permitting 360.degree. rotation about both yaw and roll axes includes a cylindrical compass housing flooded with semiconductive fluid to permit transmission of a digitally multiplexed signal from a remote reading compass to a processing unit in which the fluid is interposed between spaced-apart plates located along and perpendicular to the roll axis of the compass. This permits electrical connection to and from the compass, and permits not only 360.degree. rotation about the yaw axis for compass heading readout, but also 360.degree. rotation of the compass about the roll axis to permit use in seismic streamers.