Flat Earthers

There is a lot of nonsense talked about flat-earthers. It is used as a stick to beat people who disagree modern scientific theories like climate change and evolution. In fact nobody has believed the earth was flat since the start of the iron age except in 17th century China and Terry Pratchett fans. The misconception that educated people at the time of Columbus believed in a flat Earth, and that his voyages refuted that belief, has been referred to as "The Myth of the Flat Earth". (Members of the Historical Association (1945). Common errors in history. General Series, G.1. London: P.S. King & Staples for the Historical Association. , pp.4–5. The Historical Association published a second list of 17 other common errors in 1947.) As early as the venerable Bede (c.672 – 735) the common view among Christians was that the earth was an orb.He wrote in his influential treatise on computus, The Reckoning of Time, that the Earth was round ('not merely circular like a shield [or] spread out like a wheel, but resembling] more a ball'), explaining the unequal length of daylight from "the roundness of the Earth, for not without reason is it called 'the orb of the world' on the pages of Holy Scripture and of ordinary literature.

Flat-earthism became the province of weirdos and mad Americans. For example: In 1956, Samuel Shenton set up the International Flat Earth Research Society, better known as the Flat Earth Society, as a direct descendant of the Universal Zetetic Society, just before the Soviet Union launched the first artificial satellite, Sputnik. He responded to this event "Would sailing round the Isle of Wight prove that it were spherical? It is just the same for those satellites." His primary aim was to reach children before they were convinced about a spherical Earth. Despite plenty of publicity, the space race eroded Shenton's support in Britain until 1967 when he started to become famous due to the Apollo program. His postbag was full but his health suffered as his operation remained essentially a one-man show until he died in 1971.

There is a portion of the earth that is flatter then it ought to be; I mean at the two poles; the earth has flattened head and feet making it officially oblate rather than absolutely spherical. How did they discover that?

I obtained this from the current New Scientist.

In 1671, France sent astronomer Jean Richer to South America to map the skies of the southern hemisphere. Richer, whose work helped the French navy navigate the world, took with him two pendulum clocks. Though they had been carefully calibrated in Paris, he was dismayed to find that they lost 2 minutes 28 seconds per day in French Guyana compared with local clocks.

Upon his return home in 1673, this discrepancy caused an international scientific uproar. Isaac Newton declared that the clocks beat more slowly near the equator because the force of gravity was less there, and that gravity was less because the planet bulged at its waist due to the centrifugal force generated by its rotation. French scientists rejected Newton's oblate Earth, maintaining instead that the planet is pointed, rather than flattened, toward the poles.

Both sides realised that measuring the length of a degree of latitude at various points – especially near the equator and poles – would reveal the true shape of the Earth. An expedition needed to be sent to the equator to survey a line, as nearly north-south as possible, hundreds of kilometres long.

In 1733 a Franco-Spanish team of scientists, naval officers, device-makers and servants was assembled. In Measure of the Earth, Larrie Ferreiro tells the story of their adventures. They set sail in 1735, expecting to spend three or four years taking measurements in the viceroyalty of Peru. Instead, it would be nine years before any of them would see Europe again, and several would never make it. Their surgeon died by the sword, the youngest succumbed to malaria, while two were marooned in the New World for lack of money.

The team did measure the surface distance of one degree of latitude in what is now Ecuador. They found it to be 56,753 toises (a French unit of measurement at the time) – just 50 metres off today's value – proving Newton right. Ironically, by the time they reached Paris, another French team had gone north to the Arctic circle and taken measurements confirming the Earth to be oblate, ending the debate.

Measure of the Earth, by Larrie D. Ferreiro, Basic Books, £15.99/$28.