THE PRESSURE UPON THE POLES OF THE ELECTRIC ARC. 
117 
Table V. (Buknham).— Direct Curreiit. Variation of Total Pressure with Current 
and Arc-length. After Correction for Earth’s Field and Electromag]letic Effects. 
Total pressure upon anode in dynes. 
Total pressure \ipon cathode in dynes. 
Current in 
i 
ampere.? 
3 
4 
5 
6 
7 
2 
3 
4 1 
1 
_ 1 
5 
10 
Arc-length. 
mm. 
‘ 0-09 
-0'02 
0-34 
0-60 
0-71 
-0-13 
0-30 
0-72 
0-90 
1 • 13 
• 1 
1 
1 • .3 
0-70 
-0-13 
0-08 
• 
0-90 
1-7 
0-17 
0-34 
O'.59 
0-66 
0-74 
-0-25 
-0-14 
0-34 
0 • 60 
• 
9; • 9 
0-34 
0-70 
-0-35 
• 
0-83 
; 
2'6 
0-26 
-0-19 
0-24 
0-49 
3-0 
* 
0-15 
0-73 
3 ■ .5 
-0-02 
0-32 
0-57 
0-74 
- 0 • 45 
0-13 
0- 10 
0 • 36 
1-55 
3-8 
0-68 
-0-24 
0-63 
.U2 
0-59 
0-65 
• 
-0-40 
0 
0-30 
0-55 
6-0 
o-ii 
016 
0 • 56 
• 
0 • 26 
6-9 
• 
-0'53 
-0-44 
-0'14 
• 
0-43 
8-6 
0-27 
0-53 
0-68 
0'.74 
- 0 • 45 
0 • 20 
• ' 
9-0 
0'45 
10-3 
Oil 
1 
1 
1 
Table VI. 
(Bltbnham). —Direct Current. Variation of Total Pressure with the 
Current for two given Arc-lengtlis. 
Total pressure upon anode 
in dynes. 
Total 
pressure upon cathode in 
dynes. 
1 
' Current in 
amperes 
1 
2-0 
2-8 
3-5 
5-0 
7-0 
8-5 
2-4 
2-8 
4-0 
5-0 
6-0 
7-0 
pi 
8-5 
9-0 
Arc-length. 
1 mm. 
' 1-7 
i 
0-11 
0-22 
0-13 
0-45 
1-28 
1-15 
1 • 56 
1-40 
O'lO 
0-37 
0-25 
0-70 
0-75 
1-40 
1-82 
1-33 
1-60 
Direct Current. Series C. 
Observer: Mr. A. H. Davis. 
The arrangement shown in fig. 9 was adopted ; the moment of inertia of the arm 
was reduced by moving the balance weight very close to the centre of the swinging 
arm, and a vane dipping into water was added to damp tlie oscillations. The double¬ 
arc method was adopted because it eliminated the electromagnetic effects upon the 
movable parts of the circuit due to the earth’s field and to the rest of the circuit ; 
VOL. CCXX.-A. 
s 
