331 
1912-13.] Atmospheric Electric Potential Results. 
The third and fourth harmonics are of comparatively small importance, 
and it is difficult to say whether they represent real periodic changes in 
the potential gradient or whether they would get less important if a 
larger amount of material were available for discussion. Chree * discusses 
Table IV (6). 
Station. 
Period. 
Year. 
Winter. 
Summer. 
“1* 
“2* 
°i- 
a 2‘ 
“i- 
a 2 . 
Kew .... 
1898-1904 
166 
188 
206 
180 
87 
186 
Paris (B.C.) . 
1894-1898 
223 
206 
95 
197 
Paris (E.T.) . 
1896-1898 
216 
171 
Karas j ok 
1093-1904 
177 
158 
189 
155 
141 
144 
Potsdam 
1904 
194 
185 
343 
185 
Kremsmiinster 
1902-1910 
221 
188 
212 
172 
231 
196 
Edinburgh 
1912 
233 
183 
222 
161 
268 
193 
the question of the importance that should be attached to the 8- and 6- 
hour terms. He points out that “ with the exception of the values of a 4 
in winter — -when the amplitude at Kew was so small that considerable 
uncertainty must exist — the Kew and Bureau Central, Paris, values of 
a 3 and a 4 are sufficiently close to raise a strong presumption that the 
Table V. 
Year. 
Winter. 
Summer. 
«i- 
“ 2- 
«3- 
a 4 . 
“i* 
a 2’ 
a 3 . 
« 4 . 
a i- 
0C2* 
«3- 
°4* 
Kew . 
165 
186 
38 
291 
206 
180 
23 
239 
87 
186 
116 
304 
Edinburgh 
233 
183 
80 
302 
222 
161 
43 
60 
268 
193 
95 
292 
8- and 6-hour terms represent a true atmospheric electricity effect. The 
comparative agreement between the phase angles from the earlier and 
later series of observations at the Bureau Central and the Eiffel Tower 
favour the same conclusion.” The values for q 3 and a 4 obtained at 
Edinburgh seem to lead to a similar conclusion, as will be seen from 
Table V., which gives the values of cq to a 4 for winter, summer, and the 
* Phil. Trans., 206, p. 299, 1906. 
