‎"EÖTVÖS, ROLAND v. (LORÁND). - ESTABLISHING THE PROPORTIONALLITY BETWEEN GRAVITATIONAL AND INERTIAL MASS.‎
‎Untersuchungen über Gravitation und Erdmagnetismus.‎

‎(Leipzig, Johann Ambrosius Barth, 1896). Without wrappers as issued in ""Annalen der Physik und Chemie. Hrsg. von G. Wiedemann."", Neue Folge Bd. 59, Zehntes (No 10 1896). Entire issue offered. Pp. 193-416 a. 1 folded plate. Eötvös's paper: pp. 354-400 a. 15 large textillustrations, depicting his experimental apparatus. Clean and fine.‎

Reference : 43815

‎First appearance of Eötvös's main paper on gravitational phenomena, which became the subject of his lifework, and in which he showed experimentally, that the inertial mass and the gravitational mass are proportional, a discovery that became ONE OF THE BUILDING STONES OF THE THEORY OF GENERAL RELATIVITY.""The second extremely important application of the Eötvös balance involved a predetermination of the rate of gravitational acceleration for different bodies. It had been known from earlier work that all bodies fall with the same acceleration (in a vacuum), but the best previous determinations yielded only a limited accuracy. In response to a prize announcement by the University of Gottingen, Eötvös and his collaborators followed up his early measurements on this subject. The new measurements provided not merely a more accurate proof of a principle believed right until then, but much more: his results, proving that gravitational mass and inertial mass are equivalent, the possible deviation being about five parts in 109, became one of the building stones of the theory of general relativity. The experiment proves the “weak” form of the principle of equivalence, which states that the trajectory of a test particle, under the influence of gravitational fields only, depends only on its initial position and velocity, not on its mass and nature. Later confirmation of his results (during the last fifty years) reduced the possible deviation from perfect equivalence by a factor of 1,000."" (DSB, IV, 379 ff.).‎