PHYSICS: R. A. MILLIKAN 
235 
determination is exactly the same as the value published in 1913. The 
uncertainty in this value should now be no more than 1 part in 1000 
for it now contains but two factors which are uncertain by as much as 
1 part in 2000, namely the coefficient of viscosity of air and the dis- 
tance of fall of the drops (cross hair distance). The result of this final 
work on e may then be stated thus: 
e = 4.774 X lO-^^ ± 0.005. 
The values of the most important radiation constants may be found 
from the value of e as follows : 
TABLE 
NO. 
1 
pa 
g2/3 ^ 
g2/3 ^ 
NO. 
1 
pa 
e^^ X 108 
e^/' X 108 
1 
57.45 
63.21 
61.03 
14 
206.4 
68.90 
61.11 
2 
57.5 
63.204 
61.03 
15 
200.7 
68.97 
61.39 
3 
63.0 
63.54 
61.16 
16 
227.8 
69.88 
61.27 
4 
86.7 
64.27 
60.97 
17 
262.4 
70.85 
60.94 
5 
90.6 
64.63 
61.21 
18 
281.4 
71.60 
60.98 
6 
101.3 
65.02 
61.19 
19 
321.4 
73.34 
61.20 
7 
102.4 
65.07 
61.20 
20 
345.4 
74.27 
61.22 
8 
106.3 
65.13 
61.11 
21 
359.1 
74.54 
60.97 
9 
109.7 
65.19 
61.05 
22 
371.5 
75.00 
60.97 
10 
107.3 
65.21 
61.16 
23 
380.6 
75.62 
61.24 
11 
150.6 
66.70 
61.01 
24 
388.5 
75.92 
61.24 
12 
160.1 
67.12 
61.07 
25 
438.3 
77.74 
61.18 
13 
155.6 
67.14 
61.26 
Mean— 61.126. 
Bohr's theory s gives the constant of the B aimer series in hydrogen as 
I have directly determined h photoelectrically^ with an error of no 
more than 0.5%, the value from my sodium curve coming out 6.56 X 
10~2^. Webster 's^"^ value found by the method discovered by Duane 
and Hunt^^ is 6.53 X 10~27. From the mean of these two recent de- 
terminations of /?, the foregoing value of e, and e/m = 1.767 X 10^, the 
Rydberg constant is found by (1) to be 3.294 X 10^^ Its experimental 
value known with the great precision attained in all wave length meas- 
urements is 3.290 X 10^^. This agreement constitutes most extraordi- 
nary justification of Bohr's equation and warrants the use of this spec- 
troscopic data, combined with the foregoing data on e for a most exact 
evaluation of h. The value thus obtained is 
h = 6.547 X 10" d= 0.011. 
