The 1919 total solar eclipse: light and shadow over Edwin Turner Cottingham

The observations made during the 1919 total solar eclipse by the two British expeditions which observed totality in the city of Sobral in Brazil and in Príncipe, a small island in the Gulf of Guinea, then part of the Portuguese colonial empire, provided an opportunity to test one of the three astronomical predictions in the general relativity theory put forward by Albert Einstein in 1915: the deflection of light due to the Sun’s gravitational field. The Sobral expedition included two astronomers from Greenwich Observatory—Charles Rundle Davidson and Andrew Claude Crommelin; the expedition, which observed in Príncipe, included the astrophysicist Arthur Stanley Eddington, and the clockmaker and precision time expert Edwin Turner Cottingham. This article will focus on Cottingham, the most overlooked of the four observers. His participation and role in the 1919 expeditions will be addressed in the context of his personal and professional biography. By clarifying Cottingham’s role in the expeditions within the context of his career as a reputed precision timekeeping expert, this article highlights the historiographical risk inherent to narratives that aim to bring to light invisible or less regarded actors: they often privilege participation in an epoch-making scientific episode at the expense of casting a shadow on other technical accomplishments.