Category: Refraction reported as missing curvature

The list below is believed complete, though membership – like everything here – is subject to revision.

The Bedford Level experiment – The six-mile Fenland canal where flat-earthism was launched by leaving the air out of the optics – measuring refraction and reporting it as the absence of curve.
Celestial theodolite – A flat-Earth method that measures atmospheric refraction with great care and records it as the absence of curvature.
Flat Earth – The cosmographies that decline the curvature of the Earth – the umbrella under which the encyclopedia's several flat doctrines are gathered.
Samuel Rowbotham – English founder of modern flat-Earth doctrine (1816–1884), whose 'zetetic' method sought a flat world from a fixed conclusion – and whose canal experiment measured only refraction.
Selenelion – The Sun and the totally eclipsed Moon seen at once, from opposite horizons, in a geometry that places them exactly opposite and therefore forbids it.