Our current geopolitical context invites us to reconsider how nations have collaborated on scientific projects throughout history. France and Britain’s scientific relations, marked by rivalries but also by fruitful cooperations, offer a remarkable example. To showcase this, the Académie des sciences and the Royal Society have jointly curated an exhibition devoted to a major scientific question debated over several centuries: the exact shape and size of our planet Earth.

Since the Antiquity, it has been known that the Earth is a sphere, but generations of scientists have refined this model, proposing new theories and providing new measurements using ever more precise instruments. From the 17th century onwards, French and British scholars engaged in a major scientific controversy concerning the precise figure of the Earth and its possible flattening at the poles. Voltaire summarised this vast debate in 1734 in his Lettres philosophiques with a quip that has remained famous: "In Paris, you imagine the Earth shaped like a melon; in London, it is flattened on both sides." The rich exchanges between the Royal Society, founded in London in 1660, and the Académie des sciences, founded in Paris in 1666, highlight the essential role of theoretical debate and of the circulation of instruments, data, and ideas in the development of knowledge.

This collaborative exhibition brings together for the first time in France objects, printed and manuscripts sources from the French and British academies of sciences alongside contributions from the bibliothèques Mazarine & de l’Institut de France, to trace the theoretical, experimental, and observational approaches developed on both sides of the Channel to measure, model, and understand the size and shape of the Earth, from the 17th century to the present day. It features prominent figures including Isaac Newton (1642-1727), his French translator Émilie du Châtelet (1706-1749), Jean Le Rond d’Alembert (1717-1783), Charles Marie de La Condamine (1701-1774), and Henri Poincaré (1854-1912).

While the Newtonian hypothesis defended by British natural philosophers ultimately proved correct, these exchanges over such long periods illustrate above all the dynamics inherent to science: a collective process based on informed debate, corrections, and the progressive improvement of models, within a framework where disagreement excludes neither mutual respect nor intellectual cooperation.

A joint exhibition by the Académie des sciences and the Royal Society,
with contributions from the bibliothèques Mazarine & de l’Institut de France.