ATLAS

DivergenceOMEGA-3-18-4Sheet 4 of 5 of the dossier Flat Earth

Putting it to the test: from the Bedford Level to Behind the Curve

The experiments run since 1838, by supporters and by sceptics, and what they measured.

A river seen from a road bridge, running between flat banks.
The Old Bedford River at Welney, looking upstream from the road bridge, site of the Bedford Level experiments. Bob Jones · CC BY-SA · Wikimedia Commons

Summary

The theory has been tested repeatedly, often by its own supporters. In 1838 Samuel Rowbotham watched a boat with a flag on its mast row away along six miles of the Old Bedford River and reported that it stayed in view all the way, which he took as proof of a flat Earth. In 1870 the naturalist and surveyor Alfred Russel Wallace repeated the test for a wager, set his sight line higher to reduce refraction and added a pole in the middle of the canal: he found the curvature a sphere predicts and won the bet. In 1901 Henry Yule Oldham reproduced his result with three poles, a version taught in English schools until photographs from space became available. In 1904 a photograph of a white sheet six miles away, commissioned by Lady Blount, seemed to support Rowbotham, but atmospheric refraction can produce the results he and she noted.

Later tests went the same way. In the 2018 documentary Behind the Curve, a ring laser gyroscope used by believers detected the actual 15-degree-per-hour rotation of the Earth, which they dismissed, and a laser test over water failed to align as expected. At the Salton Sea in June 2018 a sceptics' test showed the curvature, and flat Earth supporters present rejected the result.

What the thesis says

The sources show where these claims circulate, not that they are true.

  1. Thesis

    In 1838 Rowbotham used a telescope held 8 inches above the Old Bedford River to watch a boat row away, and reported that it stayed in view for the full 6 miles to Welney Bridge; he claimed that this proved the Earth to be flat.

    • Bedford Level experiment, Wikipedia
      He reported that the vessel remained constantly in his view for the full 6 miles (10 km) to Welney Bridge
A photograph taken over the water, in which a pale patch at the centre is the bridge, with small square dots for the white sheet and its reflection.
Photograph of the Bedford Level taken by Edgar Clifton on 11 May 1904 for Lady Blount's attempt to prove the Earth flat; refraction explains the result. Edgar Clifton (photographer) · public domain · Wikimedia Commons

Verified facts

  1. Verified fact

    In 1870 Alfred Russel Wallace, a surveyor, set the sight line 13 feet above the water to reduce refraction and added a pole mid-canal; he found a curvature consistent with a spherical Earth and won the wager with a flat Earth supporter.

    • Bedford Level experiment, Wikipedia
      Wallace, by virtue of his surveyor's training and knowledge of physics, avoided the errors of the preceding experiments and won the bet.
  2. Verified fact

    In 1901 Henry Yule Oldham reproduced Wallace's result with three poles of equal height: the middle pole appeared about 6 feet higher than the end poles, a version taught in English schools until photographs of the Earth from space became available.

    • Bedford Level experiment, Wikipedia
      the middle pole was found to be about 6 feet (1.8 m) higher than the poles at each end.
  3. Verified fact

    Atmospheric refraction can produce the results noted by Rowbotham and by Lady Blount's 1904 photograph of a white sheet six miles away, because near-horizontal light rays bend downward.

  4. Verified fact

    In the documentary Behind the Curve, flat Earth advocates carry out experiments whose results confirm that the Earth is a globe, and the results are discarded.

    • Behind the Curve, Wikipedia
      In the film, flat Earth advocates carry out experiments to test the hypothesis that the Earth is flat, the results of which confirm that the Earth is a globe, and so are discarded.
  5. Verified fact

    One group in the film used a ring laser gyroscope to show that the Earth was not rotating; it detected the actual 15-degree-per-hour rotation of the Earth, a measurement the group dismissed as corrupted by the device picking up the rotation of the firmament.

  6. Verified fact

    Another group used lasers across several miles of still water; the water surface was in fact bent by several feet over the distance measured, and the group dismissed the experiment as inconclusive.

    • Modern flat Earth beliefs, Wikipedia
      the surface of the still water was in fact bent by several feet over the distance measured
  7. Verified fact

    On 10 June 2018, at the Salton Sea, sceptics demonstrated the curvature of the Earth through the disappearance of boat-based and shore-based targets with distance; flat Earth supporters present rejected the result.

    • Modern flat Earth beliefs, Wikipedia
      This experiment successfully demonstrated the curvature of Earth via the disappearance over distance of boat-based and shore-based targets.
A diagram of what Wallace saw through his level at the Bedford Level.
The view through the level used by Alfred Russel Wallace in the 1870 Bedford Level experiment. Chris55 · public domain · Wikimedia Commons
Play on YouTube (third-party content)
Official release trailer of the 2018 documentary Behind the Curve, which follows the flat Earth community; it documents the thesis and its experiments.
Delta-v Productions