110 PROCEEDINGS OF THE ACADEMY OF [1888^ 



J^ = Number of divisions of scale corresponding to deflection; 

 of magnet including the wire of the compensator. 



E = The electro motive force of the Daniell element. 

 Substituting the value of n and of J and J' obtained experiment- 

 ally as described above and equation (3) becomes: — 



820 90-81 



^~ 1000 ^90 ^ 

 or 



X= -^j E = 0-0833 D. 



that is to say the electro motive force of the muscle or X that 

 deflected the magnet to an extent corresponding to 267 dimensions 

 of the scale is equal to 0"0833 of a Daniel element. 



Finally it will be observed that the graduating of the compensa- 

 tor or the determining the amount of the iractional portion of the Dan- 

 iell necessary to compensate the muscle current is accomplished imme- 



j ji I 



diately after compensating or before, since -^ j from (3) ~ 



N J ^ ' 10000 



of the Daniell, that is each division of the wire of the compensator 

 at that moment switches oft* the roOToth of a Daniell and as it required 

 820 such to compensate, yf f o o ^=t2 was the fractional portion of the 

 Daniell element needed. It need hardly be added that in determin- 

 ing the electro-motile force of a nerve, we proceed in exactly 

 the same way except that we make use of the diverting vessels as 

 electrodes instead of diverting cylinders. 



It may be mentioned incidentally that in all of the experiments 

 performed in the above manner the telescoi)e and scale were 

 placed at a distance of 2'5, met (8 feet) from the galvanometer, the 

 coils lay close up to the magnet, that the temperature of the lab- 

 oratory was about 70°F. (38-9 C) the season January and February, 

 the time of day noon. The following table gives the results synop- 

 tically arranged of 25 experiments performed upon the gastrocnemius 

 of the frog and of 25 experiments upon the sciatic nerve of the same 

 animal. Resuming, it will be observed that the average deflection 

 of the magnet due to the electrical current of the muscle corresponded 

 to 217 divisions of the scale, the electro-motive force causing the same- 

 thc fith of a Daniell or 0'0696 D. a greater electro-motive force 

 than that yet obtained, the same amounting according to Du Bois 

 Key mond ^ to 0-035— 0-075 D. the mean of which is 0-055D. It juay 

 be also mentioned incidentally in this connection that the electro- 



1 Op. cit. Band II, S. 243. 



