Henry Yule Oldham, (14 December 1862 – 14 March 1951) was a teacher and geographer who, in 1901, conducted the definitive version of the Bedford Level experiment, a proof that the Earth is a sphere.
[4][5] In 1838 Samuel Rowbotham of the Universal Zetetic Society had claimed to demonstrate that a six-mile length of the Old Bedford River, Cambridgeshire, had a flat surface and not, as would be expected if the earth were a sphere, a curved one.
In 1870 on the same spot the noted explorer Alfred Russel Wallace, a trained surveyor, soundly disproved the observation, but the mystery was not allowed to rest and Rowbotham's supporters continued to argue their case with great vigour in the courts, in scientific journals and in pamphlets.
In 1901 Oldham used a plate camera and theodolite for his careful observations along the length of the river and he presented his results at an illustrated lecture held at the British Association for the Advancement of Science.
[6][7] His experiment, because of its photographic proof, is regarded as definitive and was taught in schools[8] until images taken from orbiting satellites became available.