254 THOMPSON YATES LABORATORIES REPORT 
Adding together the figures from the four experiments obtained by the applica- 
tion of the general principle to the data collected. 
Calculated 1225 x io~ 5 Daniell. 
Found 1 1 68 x io~ 5 ,, 
Total Difference 57 x io~ 5 Daniell. 
or a difference of 4-6 per cent. 
The experiments have naturally been selected from others providing similar 
evidence, and have been chosen on account of the exactness of the agreement between 
value calculated and found. 
Nor is this unfair as practice was obtained in performing the series of measure- 
ments required : tor each experiment increased the rapidity with which they were 
taken, and led to important modification in the convenient arrangement of the 
necessary apparatus. The experiments were also made unsupported by the knowledge 
that their results must, if correct, be of the nature given. 
The next and last experiment recorded in this section affords not only a con- 
firmation of the results previously given, but also illustrates a new point. From its 
data it may be seen that Helmholtz's general principle is not only true of the injury 
current but also of ' longitudinal currents.' In either case the institution of the 
outer observation circuit modifies the distribution of potential upon the surface and 
in the interior of the nerve and in the same way. The current which passes from 
point (1) to point (2) in the outer wire path also traverses as a new phenomenon the 
nerve from point (2) to point (1). 
EXPERIMENT E 
Sciatic Nerve of Cat 
Nerve on electrodes A, B, C, D. Cross section at A. 
Length of AD ... ... 4 centimetres. 
BC ... ... r6 
AB ... ... 07 
Directly measured resistance of AD ... ... 13,000 ohms. 
BC ... ... 10,700 „ 
,, ,, Electrodes ... 6,000 ,, 
Resistance of BC calculated = 13,000 x r6 = 5,200 ohms. 
4 
Potential difference between AD (A — ) "01450 Daniell. 
BC (B— ) -00448 Daniell. 
