108 Messrs. Le Rossignol and Gimingham on 
and for a difference of potential of 1 volt between the quad- 
rants, the spot of light travelled through 120 mms. 
The apparatus was almost identical with that described by 
Prof. Rutherford; one pair of quadrants was permanently 
earthed while the other pair was connected to the central 
rod R of the emanation cylinder C, and so arranged that the 
quadrants could be earthed at will by means of the key K 
recommended by Rutherford. The rod was insulated from 
the external cylinder bya plug of shellac, into which a guard- , 
ring connected to “ earth” was inserted. After considerable | 
trouble the apparatus was brought into such a condition that 
no sensible leak could be detected in five minutes, and con- 
sequently no correction was necessary for it in the present | 
experiments. | 
The charge was proved to be proportional to the deflexion | 
throughout the scale by placing some uranium oxide (giving 
a constant current) inside the cylinder and reading the 
deflexion at intervals of five seconds. On plotting these 
values against the time, a straight line was obtained. 
A battery of test-tube accumulators was used to create a 
difference of potential of 300 volts between the central rod 
and the emanation cylinder. 
‘s 
| 
1 
Time, Scale- | Time Scale- Time Scale- || Time Scale- 
in secs. readings.) in secs.| readings. | in secs.] readings. |in secs.! readings. 
cms. | cms. ems. = ¥| cms, 
0 0 || 100 1385 |) 200.) 17-77. ||: 800 18-96 
| 5 | 115 | 105] 142 || 205) 17°89 -|| 305 19-0 
ENO: aro 0 ag 145°. | 210 | ©1799" | 310 |* "Teal 
| 15 $22 | 5 | 148 | 215 | 1809 | 315 | 1917 
20 4:92.11 120 |. 15-07.)|| 220)|.. 1814 =| 320 19-2 
| 25 | 52 || 125 | 153» | 295 | 1822 | 325 | 1999 
| 380 604 130 15°56: | |280 18:3 330 | 19:26 
35 68 || 135 | 158 |] 235 | 1835 || 335 | 19°08 
40 764 | 140 | 1602 | 240 | 1841 | 340 | 1930 
| 45 85 || 145 | 1618 || 245 185 345 19:32 
) SOslaesOs | 1s pies |) Sac 1e-bs” | 350 19°33 
55 | 978 || 155 166, || Saba" 186. || 855 19:37 
60 | 1037 | 160 | 1678 || 260 | 1865 || 360 | 19:87 
65 | 110 | 165 |} 1688 | 265 | 1860 | 365 19:39 
70) 15) | 170 | v0 | 270) 1868 || 370 19-4 
75 1202 175) 1717 (|) 275) 187 «| 375 ieee 
; 80.4125 9) 180.1 17:3. || 280 | 18-76 -.|| 380: eee 
85 | 12:88 | 185 | 17-44 || 285) 1884 | 385 | 195 
90 (1327 | 190 1756 200} 1891 390 | 19°54 
95 | 1864 | 195 17°68 | 295 | 189 | 306 19°58 
| | | | | 400 | 19°6 
| 
Kach experiment was carried out as follows:—A definite 
quantity of emanation was blown into the cylinder as quickly 
