Adjustable magnetic compass

• US 5,528,837 A
• Filed: 10/02/1995
• Issued: 06/25/1996
• Est. Priority Date: 03/16/1993
• Status: Expired due to Term

• Current Assignee: Bell Automotive Products Incorporated (Hoppy Holdings Corp.)
• Original Assignee: Cobbs Manufacturing Co.
• Inventors: Schenken, John E., Hartmann, Jerome, Haas, Charles A.
• Primary Examiner(s): Will, Thomas B.
• Application Number:
  US08/538,465
• Time in Patent Office: 267 Days
• Field of Search: 33/355 R, 33/349, 33/361, 33/358, 33/359, 33/356, 33/357, 33/364, 33/1 D
• US Class Current: 33/356
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses

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.

Claims

1. An adjustable magnetic compass for adjustably compensating for the magnetic variation between magnetic north and map north, the adjustable magnetic compass comprising:

a geographic chart visually identifying a plurality of specific geographic regions, each geographic region containing a unique indicia therewithin specifying a required amount of adjustment to be made when the adjustable magnetic compass is physically within the geographic region;

a housing for operatively encasing a compass dial wherein the compass dial includes a plurality of indicia representative of directional positioning of the adjustable magnetic compass;

a lubber line operatively associated with the housing for visual referencing relative to the indicia on the compass dial in order to indicate the directional positioning of the adjustable magnetic compass;

means for adjusting the lubber line relative to the indicia on the compass dial, to, in turn, visually compensate for the magnetic variation between magnetic north and map north relative to the physical geographic location of the adjustable magnetic compass; and

means for identifying that an appropriate amount of adjustment to the lubber line has been accomplished, the identifying means comprising a plurality of projections fixedly attached to the housing and referenced relative to the lubber line, wherein each of the projections are representative of a corresponding one of the unique indicia associated with the particular geographic region on the geographic chart and, accordingly, the geographic region where the adjustable magnetic compass is physically located.

2. The adjustable magnetic compass according to claim 1, wherein each geographic region within the geographic chart is identified by a numeral corresponding to a specific one of the projections of the housing.

3. The adjustable magnetic compass according to claim 1 further including means for releasably securing the lubber line in a position relative to a specific one of the plurality of projections.

4. The adjustable magnetic compass according to claim 1 further including means for releasably securing the lubber line in operative aligned position with a specific one of the indicia on the compass dial.

5. The adjustable magnetic compass according to claim 1 wherein the lubber line adjustment means includes a grasping member operatively associated with the lubber line.

6. The adjustable magnetic compass according to claim 1 wherein the lubber line is attached to a rotatable dome member;

the dome member being operatively attached to the housing of the adjustable compass and positioned over and about at least a portion of the compass dial;

the lubber line adjustment means comprising the dome member.

7. The adjustable magnetic compass according to claim 6 wherein the dome member includes a grasping element for facilitating rotation of the dome member.

8. A method for adjusting a magnetic compass to compensate for the magnetic variation between magnetic north and map north, wherein the compass includes an adjustable lubber line operatively associated with a compass housing for visual referencing relative to compass dial having indicia representative of north, south, east and west directions, and a plurality of projections fixedly attached to the compass housing and referenced relative to the lubber line, each of the projections being representative of a corresponding one of unique indicia within a geographic region on a geographic chart, the method comprising the steps of:

identifying the specific geographic region in which the compass is physically located on the geographic chart;

matching the specific indicia within the geographic region in which the compass is physically located with its corresponding projection on the compass housing; and

adjusting the lubber line to align the lubber line with the matched projection corresponding to the indicia identified within the specific geographic region in which the compass is physically located.