FOUNDING ELECTRO-DYNAMICS - OFFPRINT-ISSUE

AMPÈRE, ANDRÉ-MARIE.

Mémoires sur l'action mutuelle de deux courans électriques, sur celle qui existe entre un courant électrique et un aimant ou le globe terrestre, et celle de deux aimans l'un sur l'autre. Lus à l'Académie royale des Sciences. (Extrait des "Annales de Chimie et de Physique".) [i.e. "offprint from "Annales de Chimie et de Physique"].

(Paris, 1820).

Small 8vo. Contemporary (original?) blank blue paper wrappers. Annulated stamp to title-page, otherwise a nice, clean, and fresh copy. 68 pp. + 5 engraved plates.

First edition, in the extremely scarce off-print, of the first announcement of Ampère's seminal discoveries on electromagnetism, which laid the foundation for electrodynamics.

Ampère first heard of Ørsted's discovery of electromagnetism on the 4th of September, when Arago announced Ørsted's results to the Paris Academy of Sciences. In Ørsted's experiment, a current-carrying wire is held over and under a compass needle - the result being that the needle is positioned at 45 degrees in respect to the wire. Ampére immediately saw that this result made no physical sense and realized that the true nature of the effect could not be observed until the force of terrestrial magnetism was somehow neutralized; what Ørsted had observed and reported on was the resultant of the force from the wire and that from the earth's magnetic field. Ampère discovered that the compass needle sets at 90 degrees to the current-carrying wire, when the effect of terrestial magnetism is eliminated. He also observed that current-carrying wires which are formed as spirals act as permanent magnets, and this lead him to his theory that electricity in motion produces magnetism and that permanent magnets must contain electrical currents. And thus Ampère laid the foundation of the new field of electrodynamics.

"Ampère, professor of mathematics at the Polytechnique, heard of Oersted's discovery and immediately set up a series of experiments to determine the exact relationships of current-flow and magnetism. In a week Ampère presented the first of a series of papers establishing the laws of forces acting between conductors carrying current." (Dibner). Ampère's seminal results were announced in a series of memoires read before the Paris Academy of Sciences in September and October 1820. These memoires were first published in the September and October issues of Arago's "Annales de Chimie et de Physique", and in November Ampère had the scarce seperate printing of his findings published under the title "Mémoires sur I'action mutuelle de deux courans électriques, sur celle qui existe entre un courant électrique et un aimant ou le globe terrestre, et celle de deux aimans I'un sur I'autre". It is this publication that is considered "his first great memoir on electrodynamics" (DSB).

Sparrow: 8; Dibner: 62; Honeyman: 83; Barchas 51 (only the periodical-issue); Wheeler 762 (only the periodical-issue).

Order-nr.: 51054