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. His experiment, because of its photographic proof, is regarded as definitive and was taught in schools until images taken from orbiting
satellites became available. ==Selected works==