and related branches, was one of those fortunate young men, says Prof. Heller, who appear, by the nature of their faculties, to be specially adapted to their calling. His rare mathematical talent adapted him to the use of analytical aids to such an extent that he could always readily bring the best methods to the solution of any problem. On September 4, 1847, he took his degree from the University of Königsberg. In the following spring he began his professional career at the University of Berlin as a Privat-Docent. He had already, while a student, in 1845, published a paper in Poggendorff's “Annals” on electric conduction in a thin plate, and specially a circular one, to which were appended two theorems which have since become generally known as Kirchhoff 's laws. This was followed by other valuable papers on electrical questions, among which were those on conduction in curved sheets, on Ohm's law, on the distribution of electricity on two influencing spheres, on the discharge of the Leyden jar, on the motion of electricity in submarine cables, etc. Among them also is a paper on the determination of the constant on which depends the intensity of induced currents, in which is involved the absolute measurement of electric resistance in a definite wire.
In 1850 he was appointed Extraordinary Professor and Co-director of the Physical Institute in Breslau, where he remained four years, and formed a life-long fellowship and scientific brotherhood with Bunsen. In 1854, Bunsen having preceded him thither, he removed to Heidelberg, where he had been chosen regular Professor of Physics, in place of Jolly, who had been transferred to Munich. Here he lived and taught for twenty years, the bloom-period of his life. The brightest days in the history of this great university, to whose fame and pre-eminence Kirchhoff contributed very materially, fell during the same period. To the general public, says Robert von Helmholtz, hardly anything was then known of Kirchhoff. His labors at Berlin and Breslau, being in a field wholly theoretical, had attracted the attention only of experts. "There was, therefore, some surprise in Heidelberg when the slender, remarkably youthful, modest, even bashful North German appeared, heralded by Bunsen's warm recommendations. His refined, animated speech, his courteous and attractive demeanor, his fine sense of humor and his wit, soon won him the liking of all men with whom he came in contact. He was, therefore, a welcome participant in all the social gatherings of the circle into which he fell. His friendship with Bunsen became very close. Bunsen was thirteen years his elder, strong and broad-shouldered, with a lively, commanding temperament, making his influence felt upon every one. The two men were thus quite different in their
