‎GUYE, CH.-EUG. (+) CH. LAVANCHY.‎
‎Vérification expérimentale de la formule de Lorentz-Einstein par les rayons cathodiques de grande vitesse [19. July, 1915] (+) Errata. - [CONCLUSIVELY PROVING THE LORENTZ-EINSTEIN FORMULA]‎

‎(Paris, Bachelier" Genève, Pélisserie, 1915.) 4to. No wrappers. In: ""Comptes Rendus Hebdomadaires des Séances de L'Academie des Sciences"", Tome 161, No. 3 & No. 15 (Entires issues offered). Small stamp to top right corner of each issue. Pp. 45-60" Pp. 425-448. (Guye & Lavanchy's paper: Pp. 52-55" Pp. 447-8).‎

Reference : 48589

‎First appearance of Guye and Lavanchy's famous experimental confirmation the Lorentz-Einstein formula which eventually led to a full understanding and acceptance of Einstein's theory of relativity. Einstein himself, though known as not taking much interest in the experimental support of his conceptions, wrote eulogistic letters to Guye after the present paper had been published. In February 1906 Walter Kaufmann made public his conclusion on the experiments he had been performing since 1901 on the electric and magnetic deflections of beta-rays. He claimed that Lorentz' theory of the electron, and thus ""the possibility of founding physics on the principle of relative motion"", had to be rejected. Ten years had to pass until Guye and Lavanchy confirmed the Lorentz theory and thereby proving Kaufmann's measuring equipment for imprecise. In 1915 Guye and Lavanchy measured the deflection of cathode rays at 0.25c-0.5c. They used a tube with a cathode and anode in order to accelerate the rays. A diaphragm at the anode produced a beam which was deflected. A screen was placed at the end of the apparatus, at which the impacts were photographed by a camera. They subsequently computated the ratio of transverse electromagnetic mass mT and rest mass m0 indicated by the red and blue curve, and obtained good agreement with the Lorentz-Einstein formula. Their experiments were considered by many as conclusively proving the Lorentz-Einstein formula. ""Charles Lavanchy [and] Guye was able to develop very precise techniques for measuring particle deflections within carefully controlled electric and magnetic fields. In 1916 and 1921 Guye published these methods and pronounced results in favor of the Lorentzian formulas and Einsteinian theory. Thereafter his reputation rose as a most able experimenter among the world's physicists"". (DSB). ‎