‎"FOUCAULT, (JEAN BERNARD LEON) - EXPERIMENTAL EVIDENCE FOR THE WAVE-THEORY OF LIGHT.‎
‎Sur les Vitesses relatives de la Lumière dans L'Air et dans L'Eau.‎

‎Paris, Victor Masson, 1854. No wrappers. Extracted from ""Annales de Chimie et de Physique"", 3me Series - Tome 41. With titlepage to Tome 41. Pp. 120-164 and 1 large folded engraved plate showing the experimental apparatus. Some foxing throughout.‎

Reference : 44783

‎The periodical issue of Foucault's doctorial thesis in which he for the first time showed that light slows down in water, thus giving experimental evidence for the undulatory theory of light.""He...made use of his mirror method to measure the velocity of light through water and other transparent media. As long before as the time of Huygens and Newton it had been suggested that one way of settling the dispute as to whether light was a wave form or a stream of particles was by measuring its velocity in water. According to the wave theory, light should slow down in water"" according to the particle theory, it should speed up. In 1853 showed that the velocity of light was less in water than in air, a strong piece of evidence in favor of the wave theory. He presented this work as his doctoral thesis.""(Asimov).‎