Firmament dossier · Pioneers · 3 min read

The 1870 wager: Hampden versus Wallace

Five hundred pounds, three markers and a feud that lasted years

The full text of this study is in Portuguese; the summary, key points and official view are in English.

In 1870, the zetetic John Hampden bet 500 pounds that no one could prove the convexity of a surface of still water. The naturalist Alfred Russel Wallace, co-discoverer of natural selection alongside Darwin, accepted. On the same Bedford canal, three markers of equal height were set up along six miles; through the telescope, the middle marker appeared higher than the end ones, and the referee gave the victory to Wallace. Hampden and his representative, William Carpenter, never accepted the result. The dispute turned into lawsuits, prison and years of threatening letters, and Carpenter later published “One Hundred Proofs That the Earth Is Not a Globe”.

Key points

  • The observation was made on 5 March 1870 on the Old Bedford Level.
  • The markers stood about 4 metres above the water, to reduce refraction.
  • The referee was John Henry Walsh, editor of The Field magazine.
  • William Carpenter, the referee chosen by Hampden, claimed the observation proved flatness.
  • Carpenter published One Hundred Proofs That the Earth Is Not a Globe in 1885.

What the official version says

For science, Wallace’s setup, with a high line of sight and an intermediate marker, is the correct way to measure curvature, and the result was the one expected for an Earth with a radius of about 6,371 km. The episode is cited in history of science books as one of the first public debates about the experimental method.

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