Category: Geometry & cosmography

A top-level category of Obscuripedia. The list below is believed complete, though membership — like everything here — is subject to revision.

• 180-degree plane — Claim that the equator is a 90-radian circle forming one flat plane that contains all land.
• Babylonian Map of the World — The oldest known map of the whole world — a clay disc ringed by a "Bitter River", and so also the oldest flat-earth map.
• Celestial theodolite — A flat-Earth method that measures atmospheric refraction with great care and records it as the absence of curvature.
• The Concordant Orrery — The Aetheric Concord's late mechanical model of the flat cosmos — built to need no globe mathematics, and set entirely from the globe's own almanac.
• The doctrinal value of π — The belief that π ought to be a clean, rational number — most often 3.2 — once very nearly fixed by a vote of the Indiana legislature.
• Egyptian cosmology — The world of Geb and Nut: a flat earth and an arched sky, held apart by a god posted permanently between them.
• Eight inches per mile, squared — The flat-Earth drop rule — a correct approximation of the Earth's curvature, cited chiefly by people who then fail to find it.
• The figure of the Earth — The measured shape of the planet, and the long labour of measuring it.
• The Final Experiment — The December 2024 expedition that took flat-earthers and their critics to Antarctica to watch the Sun decline to set.
• Firmament — The solid dome of the sky in ancient and biblical cosmology — figurative to most, load-bearing to the Aetheric Concord.
• Flat — Of no curvature anywhere — a plane. A stronger condition than 'level' or 'horizontal': a tilted floor is flat but not level, and still water is level but not flat.
• Flat Earth — The cosmographies that decline the curvature of the Earth — the umbrella under which the encyclopedia's several flat doctrines are gathered.
• Gai tian — The oldest Chinese cosmology: a round heaven canopy over a flat, square earth — and the gnomon that measured its height.
• Geocentrism — The doctrines that decline the motion of the Earth, holding it fixed at the centre of things.
• Hindu cosmology — The Puranic world: a vast flat disc of ring-continents around Mount Meru, set in cycles of time a single day of which outlasts the Earth's age.
• Horizontal — The plane perpendicular to the plumb line — flat, and tangent to the level surface, but true only where it is taken; two distant horizontals are not parallel.
• Level — The geodetic sense of the word: a surface everywhere perpendicular to gravity, and therefore — over any distance — curved. Still water is the demonstration.
• Norse cosmology — The walled middle-world of the Eddas: a flat Midgard ringed by the world-serpent and roofed with a giant's skull.
• Radian — The standard SI unit of plane angle (≈ 57.2958°) — and the encyclopedia's most misread object.
• Value of one radian — The doctrinal claim that one radian is 57.30 nautical miles, obtained from 360 ÷ 2π.
• Whole-radian geometry — Discredited system in which a circle holds 360 radians, a radian is a distance, and a turn is 4π.

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