ioo HERMANN VON HELMHOLTZ 



mechanical relations plain to himself and others by theoretical 

 analysis. On July 22, du Bois-Reymond presented the abstract 

 of the theorem to the Academy, and wrote on August 3 to 

 Helmholtz : l What a cornucopia of communications you shower 

 on us ; such fertility is unheard of. But your comparison with 

 Gauss's law of the compensation of internal magnetic forces 

 by surface-distribution does not please me : why should your 

 theorem not appear sui generis ? For the rest it consoles me 

 that Kirchhoff, with whom I often discussed the problems that 

 are so easily handled in the light of the new theorem, also 

 failed to solve them. The theory of nerve and muscle 

 currents is at last demonstrable, and that hideous Chapter III 

 of my book can be reduced to a short and elegant exposition/ 



But the elaboration of the memoir designed for Poggendorff 

 involved many difficulties, since in addition to the theorem so 

 greatly admired by du Bois, which was at least comprehensible 

 without recourse to higher mathematics, it also comprised the 

 deduction and application of the most difficult propositions of 

 the Theory of Potential, of which almost all the German physi- 

 cists of the day, with the exception of Neumann, Weber, and 

 Kirchhoff, were ignorant. 



In the middle of November Helmholtz writes to Kirchhoff: 

 ' I have not yet elaborated my theory of current-distribution 

 in regard to animal electricity, because new problems are per- 

 petually cropping up. I am hampered by the want of Green's 

 works, and by the fact that Neumann has not yet published 

 anything on these questions. I cannot talk to him freely 

 about it, because the propositions which I invent and use are 

 either in his unpublished notes, or are so much like his, that 

 after each discussion with him I am left doubting whether to 

 publish any given point or no. Accordingly I am debarred 

 from learning Green's theorems out of the notebooks of 

 Neumann's pupils.' 



Nor had the difficulties all been got over even by the end of 

 January, 1853. Helmholtz tells du Bois that he has been 

 unable to find a general proof of an important theorem which 

 can be easily proved for conductors in which the resistance 

 is equal in all parts, viz. that an electromotive force applied 

 to any given surface-element a of a conductor will produce in 

 any other given surface-element /3 the same component of 



