308 
MRS. H. AYRTON ON THE MECHANISM OF THE EEECTRIC ARC. 
Table I.—Mean Squares of Diameters of Mist with Corresponding Currents A, and 
Potential Differences V, between the Carbons. Numbers proportional to 
Resistances of Mist (Column 5), and Powers Expended in Mist (Column 6 ). 
Normal Arc. 
Constant Length of Arc = 2 millims. 
Solid Carbons, Positive 11 millims., and Negative 9 millims., in diameter. 
1 . 
2. 
3. 
4. 
5. 
6. 
7. 
A. 
V. 
D 2 . 
D* 
A' 
1 
_ 
D 2 ' 
A 2 
Id 
From 
Experiment. 
A 2 
~D 2 ' 
From 
Equation. 
4 
51-7 
4-8 
1-20 
0-208 
3-33 
3-4 
6 
49-0 
9-8 
1-63 
0-102 
3-67 
3-68 
8 
48-0 
16-2 
2-02 
0-061 
3-95 
3-95 
10 
47-0 
23-4 
2-34 
0-043 
4-27 
4" 22 
12 
45 • 7 
34-9 
2-91 
0-029 
4-13 
4-49 
14 
45-1 
41-2 
2-94 
0-024 
4-76 
4-76 
There is Noticing to show that the P.D. betiveen the Carbons Divided by the Current 
is not the True Resistance of the Arc. 
Fig. 6 shows that the curve connecting the values of A 7 D 3 given in the sixth 
column of Table I., with those of the current given in the first column, is a straight 
line having the equation 
A 3 /D 3 = 0-136 A + 2 - 86 . 
Fig. 6. Curve connecting the power expended in the are mist with the current. Solid carbons, 
11 millims. and 9 millims. in diameter. Length of arc, 2 millims. 
Hence, for a normal arc of given length, the power expended in the carbon mist is 
