130 REPORT—1849. 
sions. This seems at once to indicate the variability of any point that may 
be fixed on for the purpose of separating the two. Uniformity of curve 
clearly points out uniformity of action, and in endeavouring to obtain a 
knowledge of the action of the electricity of serene weather on the conductor 
and electrometers, it is to be presumed that it is to a great extent uniform 
and regular, and that consequently the curves will exhibit such uniformity . 
and regularity among themselves. This then, in the absence of some direct 
means of measuring either the electricity of serene weather or of aqueous 
vapour, must be our principal guide in endeavouring to separate them ; and 
although on some occasions greater uniformity may be obtained by either 
including or excluding particular tensions, yet upon the whole great uncer- 
tainty must prevail, if we attempt to vary the point of separation without 
more conclusive data than the mere uniformity of curve. 
Diurnal period below 60 div., Year—The 10,176 observations at all ten- 
sions are thus divided :— 
Below 60 div. ...... 7,529 
Above 60 div. ...... 2,647 
10,176 
Those below 60 div. are thus distributed among the twelve daily readings. 
TABLE XX. 
Number of positive readings below 60 div. at each observation-hour in the 
three years 1845, 1846 and 1847. 
Year. | Mid. |2 a.m./4 a.m.|6 a.m.8 a.m.{10 a.m.|Noon.|2 p.m.|4 p.m./6 p.m./8 p.m./10 p.m./Sums. 





1845.| 222 | 236 | 243 | 172 | 249 | 224 | 202 | 222 | 215 | 197 | 172] 168 | 2522 
1846.| 234 | 257 | 267 | 170 | 235 | 214 | 212 | 195 | 201 | 171 | 148) 181 | 2485 
1847.| 199 | 255 | 286 | 160 | 229 | 222 | 213 | 210 | 209 | 193 | 161 | 185 | 2522 
— | | —— — —_|— | $$ — |} | | | 


Sums.| 655 | 748 | 796 | 502 | 713 | 660 | 627 | 627 | 625 | 561 | 481 | 534 | 7529 

From a consideration of the above quantities, we find that the greatest 
number of low tensions occurred at the hours 2, 4 and 8 A.M.; 6 A.M. ap- 
pears to be excepted ; but we must bear in mind that the number 502 refers 
principally to the summer half-year; with this exception, the smallest number 
of low tensions occurred at 6, 8 and 10 p.m. It isto be remarked that these 
periods coincide, more or less, with the principal epochs of minimum and 
maximum, the whole of the observations being taken into account. 
TABLE XXI. 
Mean electrical tension below 60 div. at each observation-hour in the three 
years 1845, 1846 and 1847, with the mean diurnal period as deduced from 
the whole. 
See ee a 
Year. |Mid.|2 a.m./4 a.m.|6 a.m./8 a.m.|10 a.m.!Noon.|2 p.m.|4 p.m.|6 p.m./8 p.m.'10 p-m.|Mean. 


















div. | div. diy. | div. div. div. div. | div. div. | diy. diy. diy. diy. 
1845.|19°8|17°8 |17°5 |19°4 | 26°6 | 28°7 | 29°7 [31-4 | 30°5 | 30°5 |31°6 | 30°8 | 25-9 
1846.|24°3 | 21-2 | 21°0 }25°0 | 30:5 | 32-4 |31°3 | 30°5 | 32-0 |34°3 | 35°0 | 36°0 | 28:8 
1847.123°7 | 21-1 | 20°9 | 27-1 | 32:1 | 36°0 | 35°5 | 33-9 | 35-0 | 37:5 |38°0 | 39-2 | 31:1 


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