176 



SECONDARY ELECTROMOTIVE PHENOMENA IN 



nothing about secondary resistance. It was indeed on this occasion 

 that I discovered it, though unfortunately too late, and the whole 

 work, which would however now be behind the time, had to be 

 thrown aside. I succeeded for the first time last summer, 1882, in 

 working out a new table. Meanwhile the difficulties had not de- 

 creased, for in proportion as the means of assistance were perfected 

 the demand for accuracy had increased also. I took as the normal 

 measurement of a frog 22 centim. from the tip of the nose to the 

 end of the longest toe. I never allowed a greater variation than 

 K a cm. I employed 14 times of closure from o"-oo6 to 25', and 

 9 strengths of current from I Daniell up to 40 Groves' cells. Not 

 counting the faults and repetitions, the number of experiments was 

 198. The present paper would not be a suitable place in which to 

 reproduce the entire table. I will only give one example of it. 



T 



I 



It is hardly necessary to say that the headings in the top row 

 show the time of closure, under one second before the first and 

 under one minute before the second of the double perpendicular lines. 

 The X means that the polarising-current is produced by 10 Groves. 

 The arrows indicate the direction of the current in the muscle. 

 The horizontal rows S contain the deflections caused by the secondary 

 current. The plus mark indicates positive, the minus mark nega- 

 tive polarisation. The sensitiveness of the galvanometer (S) was 

 diminished, only one bobbin at a distance of 3 cm. being em- 

 ployed. Two numbers bracketed represent polarisation in two 

 directions. In the horizontal rows P, are found the deflections 

 due to the primary current. As 4 // -626 is greater than t max. *, 

 the mirror of the galvanometer (P) as deflected by the primary 

 current, reaches, whenever the time of closure is equal to 4"-626 or 

 exceeds it, the deflection at which it would have been held by a 

 continuous current. The magnitude of the foregoing numbers 



1 Gesammelte Abhandlungen, vol. i. p. 302. 



