492 ' 
MESSRS. W. DE LA RUE AND H. W. MULLER ON THE 
and the needle allowed to come to rest at R in each series. These were very con- 
1 T 
corclant, and c came out ——=0*3425 by the formula c=— —, where 1 : r is the ratio 
a y 2i l ~j~ v 
of the length of one swing to the next, the swings being found to decrease very 
accurately in geometric progression. By waiting till the needle comes to rest, c may 
of course be determined directly, by means of the ratio in which any swing is divided 
by the observed resting point. Thus in fig. 16, AB : RB ; : 1 : c. These two methods 
of determining c agreed perfectly. 
The following results were obtained by making the observations on the plan just 
described. 
Tube 149 CO 3 (12 aluminium rings). 
8540 cells. The full potential determined as in diagram fig. 16 was 251 divisions. 
Earth 
Fig. 16. 
T 
nnajuna 
T' 
ElecLTvmetcr 
The positive pole of the battery was connected to No. 1 ring ; the negative pole 
and No. 12 ring to earth, and each third ring in succession from 1 to 12 was connected 
with the electrometer. 
Pressure 
Pressure 
Pressure 
Pressure 
Pressure 
6‘7 millimetres. 
4'2 millimetres. 
2‘5 millimetres. 
1*4 millimetre. 
0*9 millimetre. 
Ring. 
Potential. 
Potential. 
Potential. 
Potential. 
Potential. 
Divs. 
Cells. 
Ratio. 
Divs. 
Cells. 
Ratio. 
Divs. 
Cells. 
Ratio. 
Divs. 
Cells. 
Ratio. 
Divs. 
Cells. 
Ratio. 
1 
136 
4267 
3-78 
97 
3301 
3-03 
76 
2586 
3-04 
68 
2314 
2-83 
53 
1803 
2-21 
4 
101 
3437 
2-80 
85 
2892 
2-66 
58 
1973 
2-32 
48 
1633 
2-00 
37 
1259 
1-54 
7 
68 
2314 
1-89 
56 
1905 
1-75 
45 
1531 
1-80 
37 
1259 
1-54 
31 
1054 
1-29 
10 
36 
1225 
1-00 
32 
1088 
LOO 
25 
851 
LOO 
24 
817 
LOO 
24 
817 
1-00 
Pressure 
0‘54 millimetre. 
Pressure 
0'37 millimetre. 
Pressure 
0 14 millimetre. 
Pressure 
0'07 millimetre. 
Distance between 
12th and the 
Ring. 
Potential.* 
Potential. 
Potential. 
Potential. 
following rings. 
Divs. 
Cells. 
Ratio. 
Divs. 
Cells. 
Ratio. 
Divs. 
Cells. 
Ratio. 
Divs. 
Cells. 
Ratio. 
Inches. 
Centims. 
Ratio. 
1 
49 
1667 
175 
49 
1667 
1-40 
56 
1905 
112 
103 
3504 
0-99 
22-25 
57-1 
5-24 
4 
37 
1259 
1-32 
44 
1497 
1-26 
51 
1818 
L02 
98 
3334 
0-94 
16-20 
4L1 
3-81 
7 
35 
1191 
1-25 
40 
1361 
1-14 
51 
1818 
1-02 
101 
3437 
0-97 
10-20 
25-9 
2-40 
10 
28 
953 
1-00 
35 
1191 
LOO 
50 
1701 
1-00 
104 
3538 
1-00 
4-25 
10-8 
LOO 
* Pressure of minimum resistance 0"54 millimetre. 
