vi 



honour by which he was guided in all the relations of life. A most 

 charming and genial companion, an affectionate and constant friend, 

 he delighted those who enjoyed the privilege of his society and his 

 generous hospitality by his musical accomplishments, which were of 

 & very high order. 



G. J. 



Gustav Robert Kirchhoff was born on March 12, 1824, at Konigs- 

 berg. He began his studies in his native town under the direction 

 of F. E. Neumann, and no one who has studied the writings of both 

 these eminent men can fail to notice the great influence which 

 Neumann's teaching must have had in forming the character of 

 Kirchhoff's scientific ideas. 



In 1850 Kirchhoff went as Professor Extraordinarius to Breslau, 

 and in 1854 as Professor of Physics to Heidelberg, where he stayed 

 till 1875. In that year he accepted a chair of Physics in Berlin. 

 Gradually failing in health he had to give up his lectures, and died 

 on October 17, 1887. 



His writings, the first of which he published at the age of twenty- 

 one, cover nearly the whole range of physics, and there is hardly one 

 of them which has not marked a decided progress in the subject to 

 which it refers. 



His first paper (1845), treating of plane current sheets, was the 

 first of a series in which he deduced and applied the now well-known 

 equations for the distribution of electric currents in conductors which 

 are not linear. In 1849 an important communication appeared in 

 Poggendorff's £ Annalen,' in which, for the first time, the resistance 

 of a wire was measured in what is now known as electromagnetic 

 measure. A paper of considerable interest, " Ueber die Bewegung 

 der Elektricitat in Leitern," appeared in the year 1857. The propa- 

 gation of electric effects in wires is discussed in this paper, the 

 principal result being : " that the rate of propagation of electric waves 

 is found to be c/\/2 — that is, independent of the cross section, the 

 coefficient of conductivity of the wire, and the electric density ; the 

 rate is 41,950 (German) miles per second, or very nearly the same as 

 that of the propagation of light." In view of the important con- 

 clusions to which modern researches in electricity have led, con- 

 siderable historical interest will always attach to the above statement. 

 The remaining electrical papers treat of the oscillating discharge of 

 the Ley den jar, the distribution of electricity on two conducting 

 spheres, and of the capacity of a condenser formed of two parallel 

 circular plates. 



We have next two papers on Magnetism ; one (1853) treats of the 

 magnetism induced in an infinitely long cylinder, and the other solves 

 the problem of the magnetisation of an iron ring under the influence 



