RUTHERFORD, ERNEST - NIELS BOHR - C.G. DARWIN. - THE DISCOVERY OF THE 'PROTON'.

The Structure of the Atom. (Rutherford) + (Darwin:) Collision of 'alpha' Particles with Light Atoms. + (Bohr:) On the Effect of Electric and Magnetic Fields on Spectral Lines

London, 1914. No wrappers, but stiched. All three papers contained in: "Philosophical Magazine", Sixth Series, Vol. 27. No. 159. March 1914. The whole issue issue offered (=no. 159): pp. 397-540 and 2 plates.
Rutherford's paper.pp. 488-498. - Darwin's paper: pp. 499-506. - Bohr's paper: pp. 506-523. All clean and fine.

First edition and first printing of all three papers. Rutherford, in this paper for the first time identifies the hydrogen nucleus, and called it the 'positive electron'. He later called it 'the proton' . In his definitive paper of 1911 he estimated the radius of the nucleus, a hundred thousand times smaller than that of an atom. Darwin in his paper (offered here) gave a more precise measure.
In the first lines of the paper Rutherford outlines the content "The present paper and and the accompanying paper by Mr. C. Darwin (the second paper offered here) deal with certain points in connection with the "nucleus" theory of the atom which were purposely omitted in my first communication on that subject (Phil. Mag. May 1911). A brief account is given of the later investigations which have been made to test the theory and of the deductions which can be drawn from them. At the same time a brief statement is given of recent observations on the passage of alpha particles through hydrogen, which throw importent light on the dimensions of the nucleus." - Rutherford had studies alpha-particles intensely in the years before 1914 and proved quite conclusively that the individual particle was a helium atom with its electrons removed. The alpha particles were like the positive rays that had been discovered by Goldstein (1886), and now in 1914 (the paper offered) Rutherford suggested that the simplest positive rays must be those obtained from the hydrogen and that these must be the fundamentall positively-charged particle. He names it a 'positive electron'.
Darwin, in the paper offered "concluded from the known data:"No force proportional to some power of the distance other than the inverse square can give the dependence (the Rutherford scattering cross section) on (the initial velocity)", and he then calculated the distance of closest alpha-particle-nucleus approach.

The paper by Niels Bohr relates to "The Stark effect". In 1913 appeared "an importent new discovery: when atomic hydrogen is exposed to a static electrical field its spectral lines split, the amount of splitting being proportional to thefield strenght (the linear Stark effect). After Rutherford read this news in "Nature", he at once wrote to Bohr:'I think it is rather up to you at the present time to write something on....electric effects.'" (A. Pais). Bohrs paper on The Stark effect appeared in 1914, the paper offered here. - Rosenfeld. Niels Bohr' publications No. 10).

Order-nr.: 41545