Hand bearing compass

Claim 1

A hand bearing compass for measuring magnetic bearings in a substantially horizontal plane, the compass comprising: (a) a compass body of generally thin and flat shape, the body having upper and lower major surfaces and a longitudinal median plane, said upper major surface being generally flat; (b) a direction-finding sensor mounted in the compass body, the sensor having a direction-finding plane to be aligned substantially horizontally in use, and means mounting the sensor in the body with the direction-finding plane thereof held fixed substantially parallel to the flat upper body surface, whereby said surface provides an index for visual alignment with a remote reference to level the direction-finding plane laterally in use; (c) a first longitudinal sight projecting from the flat upper surface of the compass body, said first longitudinal sight defining a first viewing axis for visual alignment with a bearing to be measured, said first viewing axis being spaced laterally from the longitudinal median plane on one side and parallel thereto; (d) a second longitudinal sight projecting from the flat upper surface of the compass body, said second longitudinal sight defining a second viewing axis for visual alignment with a bearing to be measured, and said second viewing axis being spaced laterally from the longitudinal median plane on the other side from said first viewing axis, and parallel thereto; (e) means for actuating said sensor, said means comprising a manually engageable actuator portion disposed on the compass body on the longitudinal median plane of the compass body between the first and second viewing axes, whereby the actuator portion and first and second longitudinal sights form a substantially symmetrical array about the longitudinal median plane such that the compass body can be held by its major surfaces between the finger and thumb of either hand with the manually engageable actuator portion engaged by that hand and with one of said viewing axes unobscured; (f) a display and a memory recall actuator on the compass body; and (g) electronic microprocessor circuitry in said compass body, said circuitry being connected to the actuator portion, the sensor, the display and the memory recall actuator, and comprising: (i) means for causing said sensor to measure the value of the magnetic bearing along the viewing axis upon operation of the manually engageable actuator portion, and to display the value on the display; (ii) memory means for storing a plurality of magnetic bearing values so measured, and (iii) memory recall means for recalling plural stored bearing values to the display upon operation of the memory recall actuator.