On Fizeau's Experiment

Abstract

IN two papers published in the Proceedings of the Amsterdam Academy (vol. xvii., 445, 1914; vol. xviii., 398, 1915) an experimental investigation concerning Fresnel's convection-coefficient for light of various colours was described. The main object of my repetition of Fizeau's experiment, in the improved form introduced by Michelson, was to decide between the expressions for the convection-coefficient given by Fresnel and by Lorentz. As a review of the papers mentioned has appeared in NATURE (vol. xcvi., 430, 1915), I may be permitted to give here a short account of further progress. It may suffice to recall that my results were largely in favour of the Lorentz expression with the dispersion term. For the wavelength 4500 U the difference between the two expressions under consideration amounted for water to quite 5 per cent. The probable error of the experimental result was estimated at somewhat less than 1 per cent.