Paris: Gauthier-Villars, 1850. 1st Edition. FIRST EDITION OF FOUCAULT’S DETERMINATION OF THE VELOCITY OF LIGHT, here proving that light travels more slowly in water than in air. Significantly, his findings contradicted the corpuscular theory but were in complete accord with the wave theory of light.
“In 1850 Foucault joined the debate over the then-competing particle and wave theories of light. Arago had demonstrated in 1838 that a crucial test could be made by comparing the velocities of light in air and in a dense medium, and he was experimenting to determine the velocity of light with a rotating-mirror method devised by Charles Wheatstone in 1834. Lack of success and ill health led Arago to pass the task on to Foucault in 1850.
“Success came in the same year, when Foucault observed a retardation of the velocity of light in water, giving support to the wave theory. He then saw how the rotating-mirror method could be refined to measure the absolute velocity of light in a restricted space. Foucault overcame the technical problems and in 1862 obtained a value of 2.98 x 1010 centimeters per second, the first accurate measure of this fundamental physical constant” (Encyclopedia of World Biography).
Foucault’s experiment was so conclusive that it was widely understood to have "driven the last nail in the coffin" of Newton’s corpuscular theory of light” (Cassidy, Understanding Physics).
ALSO IN THIS VOLUME: First edition of an important nerve experiment by Helmholtz marking the beginning of the field of ‘neurophysiology’. Item #480
CONDITION & DETAILS: Complete volume. Ex-libris bearing only a deaccessioned stamp on the back of the title page and slight ghosting at the spine where a spine level has been removed. 4to (11 x 8 inches; 275 x 200mm). , 886, . Bound in clean full blue cloth, gilt-lettered at the spine. Solidly and tightly bound. Very occasional toning, otherwise clean and bright throughout.