trum" (Untersuchungen über das Sonnenspectrum), was, almost immediately after its appearance, republished in an English translation. To these works, and the papers on radiation, partly mathematical and partly experimental, published in 1859 and 1860, which led up to the great work on the solar spectrum, he has added, so far as Prof. Tait has been able to discover, only three or four more recent papers, among which are one on the change of form which an elastic solid undergoes when it is magnetically or electrically polarized (Berlin Abhandlungen, 1884); a subsequent paper giving applications of the results in the same investigation; and additions to his paper on the distribution of electricity on two influencing spheres.
Prof. Heller says that Kirchhoff possessed in an eminent degree all the qualities most sought for in an academic teacher. Mr. Helmholtz sees in him the prototype of a genuine German investigator. The religion and object of his life was to seek the truth in its purest form, and express it with quite abstract unselfishness. He loved and cultivated science for itself alone, and deemed the slightest adornment or excursion from logical exactness in presenting it to be a profanation; while all mingling of it with personal motives or with the strife for honors or gain was most repugnant to him. As he acted in science, so did he in life; and what he recognized as a manly civic or official duty he pursued with logical thoroughness, divested of all personal motive. Winning amiability and goodness of heart were revealed in all of his personal intercourse, so that both in Heidelberg and Berlin he was one of the most popular of the academical teachers. He was fond of telling a story of how, when the conversation turned upon the question whether the Fraunhofer lines conveyed any information respecting the presence of gold in the sun, his banker asked, "Of what use is gold in the sun to me if I can not go and get it?" Afterward, having received an English gold medal for his discovery, he showed it to the banker, and said, "See, I have got some gold from the sun!" Having been compelled by his growing disabilities to retire from active life, Kirchhoff spent his last months with his family, preserving a living interest in the questions with which he had been occupied. He was never heard to utter a complaint, though he must have known that his powers were steadily passing away. Death came to him quite unexpectedly, while he was asleep, on October 17, 1887.
As described by Prof. Heller, he was of a stature rather under than above the average, with finely modeled, sharply cut features; having a high forehead, on which many years of continuous thought had engraved close and deeply cut wrinkles, while the penetrating glance of his deep-blue eyes bore witness to his habit of giving close attention to abstract thought.
