HENRY, JOSEPH. - DISCOVERY OF SELF-INDUCTION.

Facts in reference to the Spark, &c from along conductor uniting the poles of a Galvanic Battery.

Philadelphia, Fraklin Institute, 1835. 8vo. Later full green cloth. Tome-and titlelabels in leather with gilt lettering on spine. In: "Journal of the Franklin Institute of the State of Pennsylvania... Edited by Thomas P. Jones", Vol. XV. New series. Engraved frontisp. (2),446 pp., 2 folded engraved plates and 2 folded engraved maps. (Entire volume offered). Henry's announcement: pp. 169-70. A stamp to verso of frontispiece (Library of Congress duplicate stamp).

First printing of this importent paper, the first to describe in detail how the phenomena of Self-Induction was discovered. Henry discovered the induction phenomena - how an electric current in one coil may set up a current in the other through the development of the magnetic field - independently of Faraday, but Faraday was first to publish on electromagnetic induction. Henry's experiments with induction led him to his importent discovery of SELF-INDUCTION, which is the phenomenon in which a change in electric current in a coil produces an induced emf in the coil itself. This phenomenon was also discovered inependently by Faraday, but this time Henry had published first. The basic unit of inductance was to be called "the Henry".

Relevant to the controversy between Faraday and Henry is the following statement by A D Bache, Secretary of the American Philosophical Society introducing an abstract of Henry in J Franklyn Inst. 1835 pp. 169-70 (H. Norman 1053 and the paper offerd): "A memoir on this subject has been since submitted to the Society, containing an extension of the subject, the primary fact in relation to which was observed by Professor Henry as early as 1832, and announced by him in the American Journal of Science. Mr. Faraday having recently entered upon a similar train of observations, the immediate publication of the accompanying is important, that the prior claims of our fellow countryman may not be overlooked."(Spark Museum).

Magee "Source Book in Physics", p. 515.

Order-nr.: 47003