Dictionary term
Alidade
Direct answer
Alidade is a rotating sighting rule or telescope used to define a direction on a graduated instrument.
Alidade is a sighting rule used in historical astronomy, timekeeping, or navigation.
Alidade is a sighting rule used in historical astronomy, timekeeping, or navigation.
An engraved functional orientation; the page explains the real instrument, method, or publication.Quick reference
- Use when
- Use Alidade by aligning both sights with the target while keeping the supporting plane properly oriented.
- Do not use it for
- A bent sight, parallax, poor leveling, or a shifted pivot introduces systematic error.
- Reference category
- Historical Almanacs & Instruments
- Related terms
- Sector Instrument, Dioptra, Plumb Line, Gnomon
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The story behind Alidade
Alidades appear on astrolabes, plane tables, quadrants, surveying instruments, and later telescopic circles.
Alidade in spiritual tradition
Alidade rewards careful observation, explicit assumptions, and humility about the limits of every model or measurement.
Alidade: fact and faith, kept distinct
This is a factual history-of-science, instrument, timekeeping, or navigation reference. It may support wonder and disciplined attention without becoming a claim of fate, worship, or private revelation.
Alidade in numerology
Alidade is not a numerology claim. Any numbers attached to it should retain their ordinary scientific, calendrical, navigational, or historical meaning unless a separate symbolic interpretation is clearly labeled.
Why Alidade matters
Alidade matters because it converts a line of sight into a readable angle or plotted bearing.
Alidade at work: an example
On an astrolabe, the alidade can sight a star while its pointer marks altitude on the limb.
Where interpretation stops
Alidade is presented as sourced astronomy, calendrical, Earth-science, cultural, or instrument-history reference. Definitions should distinguish measured phenomena from civil convention and historical interpretation, preserve location and time dependencies, and avoid turning factual sky data into a deterministic personal claim.
Sources and editorial method
Research references used for this entry include:
- 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
- Also appears in
- Historical Almanacs & Instruments
- Aliases
- None listed
- Last updated
- 2026-07-16
Explore Alidade
Alidade in a book is one thing; Alidade in your own birth chart is your life. The Oracle casts your real chart and tells you what it means for your love, your work, and your year ahead, in conversation, free.
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More in Historical Almanacs & Instruments
- Astronomical Ephemeris Table
- Clepsydra
- Equatorial Telescope
- Latitude by Meridian Altitude
- Mariner's Astrolabe
- Octant
- Regulator Clock
- Star Sight
Common questions
What is Alidade?
Alidade is a rotating sighting rule or telescope used to define a direction on a graduated instrument.
How is Alidade used in an almanac?
Use Alidade by aligning both sights with the target while keeping the supporting plane properly oriented.
What should I avoid when interpreting Alidade?
A bent sight, parallax, poor leveling, or a shifted pivot introduces systematic error.
