OHM, Simon. 3 papers: (1) “Versuch über einer Theorie der durch galvanische Kräfte hervorgebrachten elektroskopischen Erscheinungen” , plus (2) “Versuch über einer Theorie der durch galvanische Kräfte hervorgebrachten elektroskopischen Erscheinungen (Beschluss)”, plus (3) "Ein Nachtrag zu dem vorsthenden Aufsatz des Hrn. Dr. Ohm”. Paper (1) in* Annalen der Physik und Chemie*, volume 6, section 4, pp. 369-514, with 1 engraved plate, with the Ohm in section 4, pp 459-469. Paper (2), in *Annalen der Physik und Chemie*, volume 7, section 45, pp 45-55 in the issue of pp 1-136. Paper (3) same issue as paper 2, pp 117-118. Each section removed from a larger bound volume, though complete in itself. VG copies. $1750

"In February an April 1826, Ohm published two important papers that dealt separately with the two major aspects of his ultimately unified theory of galvanic electricity...the second paper, “Versuch einer Theorie der durch galvanische Kräfte hervorgebrachten elektroskopischen Erscheinungen,” broke new ground in associating an electric tension with both open and closed galvanic circuits.” --Dictionary of Scientific Biography (online)

“Ohm’s second major paper of 1826 [this paper] announced the beginnings of a comprehensive theory of galvanic electricity based, he said, on the fact that the contact of heterogeneous bodies produced and maintained a constant electric tension (Spannung). He deferred the systematic exposition of this theory to a later work, however, and limited himself to stating without derivation the two equations that constituted its heart: X = kw(a/l) and u − c = ±(x/l)a, where X is the strength of the electric current in a conductor of length l, cross section w, and conductibility (Leitungs-vermögen) k produced by a difference in electric tension a at its end points; where u is the electroscopic force at a variable point x of the conductor; and where c is a constant independent of x. By means of the first equation one can, with respect to overall conducting power (or resistance), reduce the actual length of a wire of whatever cross section and conductibility to the equivalent length of one wire chosen arbitrarily as a standard. Letting l now be this equivalent length—called the reduced length (reducirte Länge) of the conductor—Ohm wrote his first law in the simpler form X = a/l, the expression which has become known as Ohm’s law. After pointing out briefly how this law, which corresponded to the one he had developed in his previous paper, embraced his and others’ findings on the conductibility of different wires, Ohm devoted the rest of the paper to developing the implications of the second, electroscopic law and to comparing these implications with previously known facts. In this work he showed that his formula successfully explained those experiments which measured the electroscopic force at different points (especially the poles) of open and closed, and grounded and ungrounded, circuits. Here again the explanatory power of his law was impressive. The fully developed presentation of his theory of electricity appeared in Ohm’s great work, Die galvanische kette, mathematisch bearbeitet (Berlin, 1827). --DSB online

## Comments

You can follow this conversation by subscribing to the comment feed for this post.