Old instruments
Magnetic Compass
Direct answer
Magnetic Compass is an instrument whose magnetized element aligns approximately with Earth's local magnetic field.
Magnetic Compass is a magnetic direction instrument used in historical astronomy, timekeeping, or navigation.
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At a glance
- Found in
- Historical Almanacs & Instruments
- Related
- Hourglass, Compass Rose, Pelorus, Celestial Navigation
Magnetic Compass is a magnetic direction instrument used in historical astronomy, timekeeping, or navigation.
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The story behind Magnetic Compass
Magnetic compasses transformed navigation but always required growing knowledge of declination and shipboard magnetic effects.
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The Book of the Sky
How people learned to read the sky, from Babylon to the day you were born.
Why Magnetic Compass matters
Magnetic Compass matters because it supplies a portable heading reference independent of visible Sun or stars.
Magnetic Compass in practice: an example
A compass course corrected for deviation and variation can be converted to a true chart course.
Where readings of Magnetic Compass go wrong
Nearby metal, electronics, local anomalies, pole proximity, and stale variation data can mislead the reading.
Sources and editorial method
Research references used for this entry include:
- National Geospatial-Intelligence Agency: The American Practical Navigator - Official modern reference for navigation principles, celestial observations, sight reduction, and navigational tables.
- Royal Museums Greenwich: Astronomical and Navigational Instruments - Museum reference collection for historical observing, calculating, timekeeping, and navigation instruments.
- Source
- The Great Almanac Dictionary
- Category
- Historical Almanacs & Instruments
- Last updated
- 2026-09-26
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Common questions
What is Magnetic Compass?
Magnetic Compass is an instrument whose magnetized element aligns approximately with Earth's local magnetic field.
What do people get wrong about Magnetic Compass?
Nearby metal, electronics, local anomalies, pole proximity, and stale variation data can mislead the reading.
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