France · Science / Astronomy. Chronological records rendered directly from the World History Database.
The first successful entirely earthbound measurement of the speed of light is carried out by Hippolyte Fizeau, measuring the speed of light in air, which is slower than the speed of light in vacuum by a factor of the refractive index of air 1.0003
Foucaults estimate, published in 1862, is 298,000 kilometres per second
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