

ON ELECTRICAL OBSERVATIONS AT KEW. 133 
The following table exhibits the distribution of the 4846 summer obser- 
vations among the twelve daily readings :— 
TABLE XXIV. 
Number of positive readings below 60 div. at each observation-hour in the 
three summers of 1845, 1846 and 1847. 
ne a Dieguito ie Pe ee RE IE oy ae ae aris SEM SE raed Papen les phen e ety 
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 pam.|8 p.m |10 p.m./Sums. 
1845.)}135] 135 | 144 | 160 | 148 | 148 | 126 | 139 | 136 | 128 | 116 | 103 | 1618 
1846.) 140} 149 | 153 | 158 | 138 | 139 | 137 | 129 | 129 | 121 | 102 | 119 | 1614 
1847. 125] 148 | 160 | 154 | 134 | 138 | 133 | 131 } 131 | 127 | 112 | 121 | 1614 








Sums.| 400} 432 | 457 | 472 | 420 | 425 | 396 | 399 | 396 | 376 | 330 | 343 | 4846 
This table exhibits a more equable distribution of observations over the 
twenty-four hours than that which has reference to the entire year; the 
greatest number occurs at 6 A.m., and the smallest at 8 p.m. 
TABLE XXV. 
Mean electrical tension below 60 div. at each observation-hour in the three 
summers of 1845, 1846 and 1847, with the mean diurnal period of summer. 
Year. |Mid.|2 a.m.|4 a.m.|6 a.m.|3 a.m.{10 a.m.|Noon.|2 p.m.|4 p.m.]6 p.m.|3 p.m.{10 p.m.|Mean. 

| 












div. | div. | div. | div. div. div. div. div. div. div. | div. div. div. 
1845.) 19.6) 16°0 | 15°8 | 19°9 | 24°5 | 27:3 | 26°6 | 29°3 | 28-4 | 29:8 131-7 | 31°7 | 24:7 
1846,| 21°0|17°4 | 18°7 | 24-4 | 29:0 | 30°1 | 27°5 | 27-0 | 28-2 | 31-2 | 31:2 | 33°3 | 26-2 
1847.) 23:5] 20°0 | 18:9 | 26°9 | 32°3 | 35°6 | 34:0 | 32°2 | 33:8 | 35-4 | 37-4 | 39°6 |30°3 


TABLE XXVI. 
Excess or defect of the mean electrical tension below 60 div. at each obser- 
vation-hour, as compared with the mean of each summer in the years 1845, 
1846 and 1847, and the mean of the three summers. 
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 div div. | div div. div. | div. | div. | div. | div. div div 
—-}-{/-|—-;-/}+/}/+/+/]/4+/4+] 4+] 4+ 
51) 8:7) 89) 4:8) 02) 26 |. 19] 46] 3:7] 51) 7:0 70 | 24:7 
—-}-}-/-—-;/+;) +) +] 4+] 4+]}]4+] 4+] 4+ 
| 52] 8B) 75] 1B] 2:8 3°9 13 | 08] 2:0) 50) 5:0 71 | 26-2 
—-|-—|-|- +/+}/+]}]+]/+]+]+ 
6°8}10°3 | 11-4 | 3-4] 2°0 3 37 | 1:9) 35 |. 5:1 | 71 93 | 303 
—|-|-|- ft pk pt pe + Pt 
ean.| 5°8; 9°3 | 9:3 | 3°4 | 1:4 3°8 233 | 24] 3:0] 5:01] 6:4 79 | 27-1 
al Tn these tables we find the forenoon maximum developed in a greater de- 
~ gree than in those having reference to the entire year—a result to be expected 
_ if the notion be correct that both low and high tensions are influenced by the 
presence of aqueous vapour in the atmosphere. The number of observations 
on which these tables are based forms a very considerable portion of the whole 
of the summer observations—rather above seven-eighths. The entire num- 
ber is 5514, from which deduct those below 60 div., and we have left 668, or 
nearly an eighth part of the whole, so that the probability of the forenoon 
and evening maxima resulting from the presence of aqueous vapour is 
