BECQUEREL, Henri. Autograph manuscript signed ("Henri Becquerel"), paper titled "Séance des cinq académies. 25 Octobre 1907." 20 pages, 2 folio, including title-leaf, 2 unnumbered half-sheets, pages numbered 1-15, and 3 blank leaves, lined paper, on rectos only, p.2 with corrected slip pasted on, pp. 4-6, 8-10 with neatly trimmed sections where illustrations were removed by the publisher for reproduction, not affecting text, few printer's marks in colored pencil, title-leaf with small note by M. Regnier dated 39 Sept. 1907 pinned at upper right corner, some light soiling and fraying at edges. Cloth folding case.
BECQUEREL ON ELECTRON THEORY. An extensive manuscript paper of Becquerel's detailed and technical lecture on the electron theory, delivered at the October 25, 1907 meeting of the Académie des Sciences on the occasion of Becquerel's election to the presidency. Becquerel's lecture discusses the principal experimental means of determining the numerical values arising from the electron theory. It is divided into sections on cathode rays, rays from spontaneously radioactive substances, and electro-optical phenomena, including the Zeeman effect.
After having been elected vice president of the Academie des Sciences in 1906, Becquerel was named President in 1907. He succeeded to the post in 1908, and was soon elected as one of the two permanent secretaries. On the occasion of his election, Becquerel provides a detailed look at electron theory. In the first section, on cathode rays, he describes methods of deriving the values e/m, v and m/e (v) for cathode rays, Lenard rays, ultraviolet light and incandescent metals. The results are summarized in a table pasted on to p.2 giving numerical amounts, together with names of theose responsible for deriving them (J.J. Thomson, Lenard, Kaufmann, Simon, Wiechert), the dates of derivation and the methods used.
The section on radiation from radioactive bodies is divided into three subsections on beta, alpha and gamma rays. He also touches on the identity of energy and mass in the context of determining the mass of the electron. The subsections on alpha and gamma rays are shorter, referring to the work of Rutherford, Bragg and Kleeman.
The longest section, on electro-optic phenomena, contains a detailed discussion of the Zeeman effect and of the theory of Lorentz: "M. Zeeman discovered that the periods of light movements emitted by an incandescent source are modified when this source is placed in a magnetic field... M. Lorentz allows that light vibrations are the result of vibrations transmitted in ether by electromagnetic phenomena which accompany the periodic movement of electrons..." Becquerel also discusses the relationship between the Zeeman effect and the phenomenon of rotating magnetic polarization discovered by Faraday, which allows the determination of e/m for a body at ordinary temperatures.
The note from the printer pinned to the title leaf indicates that the manuscript was submitted in September 1907 and that Becquerel was to receive 6 sets of proofs.