'I hav( 



PROFESSOR AT KONIGSBERG 69 



' I have not yet completed my work on the frog, as there 

 are still various experiments to make, diagrams of apparatus to 

 be drawn, &c., but I expect to finish in the Whitsuntide holidays. 

 The experiments on man must be varied and repeated before 

 I can publish them later on.' 



While working out his experiments on the frog, Helmholtz 

 was actually taking time-measurements on himself and other 

 men, which seemed to establish the rate of transmission in 

 the motor and sensory nerves of man at fifty to sixty metres 

 per second. At the end of April he announces the completion 

 of the first part of his paper, for Muller's Archiv, to du Bois- 

 Reymond, and dispatches it on July 26 along with the news 

 that he is ' father of a well-formed healthy girl '. As regards 

 new discoveries, he announces a theorem on the form of the 

 rise of electrical currents in a coil, which act inductively either 

 upon this or any connected system of other coils a task which, 

 however, took him nearly a year more before he was able to 

 deduce a conclusion. 



In the meanwhile (July 19, 1850) du Bois presented Helm- 

 holtz's comprehensive work on ' Measurements of the Time- 

 relations in the Contraction of Animal Muscles, and Rate of 

 Propagation in Nerve/ to the Physical Society. It was at 

 once published in Muller's Archiv under du Bois' supervision, 

 Helmholtz consenting, for the benefit of ' those who are only 

 half acquainted with Ohm's Law', to certain alterations advised 

 by du Bois-Reymond. He now realized from the report of 

 the latter, who had returned in a somewhat exasperated mood 

 from Paris, where his lecture on Helmholtz's method of mea- 

 suring the propagation of the nervous impulse was not very 

 "avourably received at the Academic des Sciences, that the 



velty of the work demanded a thorough exposition. The 

 article was through the press by December, and in the same 

 month Helmholtz gave a lecture to the Society of Physics and 

 Economics in KOnigsberg, of which he was this year Director 

 (being elected President two years later), which dealt in a 

 generally comprehensible manner with the subject, and was 

 entitled, 'On Methods of measuring very small Intervals of 

 Time, and their Application to Physiological Purposes.' 



In Part I of this great work (Part II only made its appearance 

 two years later), 'which opened a new and unbounded field 



O Ut. 



t 



