MEMOIK UF KIRCHHOFF. 531 



of a fall on the staircase, he suftered from a sore foot, which compelled 

 him for a long time to move only on a rolling-chair or by means of 

 crutches. It was only at Berlin that he acquired again, after many re- 

 lapses, his power of locomotion, but even after that he enjoyed his com- 

 plete health only occasionally. He lost his wife about the same time, 

 80 that his family life broke asunder. Some of his friends (Dausser, 

 Vangerow) died ; others, like Feller and my father, received calls to 

 Berlin. But accidents to his person could endanger his life, not his 

 work. He continued to perform his task as a teacher and an investiga- 

 tor under the most difticult circumstances and after most severe trials, 

 with a stoical faithfulness to duty and with iron consistency. His own 

 person and his science should have nothing to do with one another. 



Afterwards Kirchhoft' married, as a second wife, Lonise Brommel, at 

 the time matron of the university clinical hospital for the diseases of 

 the eye. His inexhaustibly cheerful and amiable tem])er made this 

 second marriagea happy one too, notwithstanding his frequent ill health. 



In the year 1875, Kirchhoff" received and ac(^epted a call to the Uni- 

 versity of Berlin, after having refused previously an invitation to be- 

 come a director of the projected solar observatory at Potsdam. 



Whether a life at Berlin is to be considered as an advantage for a 

 scientist may be doubted. The teacher acquires a larger, richer held for 

 his activity, but just so much niore is there loss of time for the investiga- 

 tor. Kirchhoff, however, owing to his infirm health, suffered but little 

 from the turmoil of the capital. He did his work as usual ; he i)ublished, 

 as he used to, a paper or so every year in the reports of the academy; he 

 did experimental work too in the laboratory of iiis friend, G. Hanse- 

 mann. He it was who, after continuous separation from Bunsen, stood 

 nearest to him as a co-worker and friend. 



But the most favorite and admirable work of Kirchhoff at Berlin (in 

 fact unique in its effect) was his coarse of lectures on mathematical 

 physics. Flis delivery captivated one and all through its external finish 

 and the i)recision of exposition. Not a word too little or too much; he 

 never bungled, hesitated, or made himself guilty of a want of clear ness. 

 The terseness of his calculus was truly admirable, — a quality not easy 

 to explain to an outsider. The whole subject rose before a hearer in 

 the shape of a highly artistic, classically perfect frame-work, in which 

 every part could be logically deduced from some other, so that it was 

 even an aesthetic pleasure to Ibllow Kirchhotf's deductions. In fact 

 Kirchhoff's lectures though intrinsically they belong to the most <litfi- 

 cult, ought to be intelligible to every one — even the less gifted — pro- 

 vided of course he is acquainted with tlie instrument used, the mathe- 

 matical language. It may ]iai)pen, and it hai)pene<l often indeed, that 

 one was not able to see the arrangement of what was put before him, 

 could not understand why and to what purpose Kirchholf made such 

 and such a deduction, l»uf to follow the train of his masters tliougiits, 

 to think th«! whole over and to leproduce it afterwards was within reach 

 of every ome. 



