—_ 

ON ELECTRICAL OBSERVATIONS AT KEw. 167 
TasLe LXXVII. 
Mean electrical tension at each observation-epoch in each month, from 
August 1843 to December 1844, both inclusive, with the mean annual 
period of 1844. 

Epochs. |Aug,|Sept.| Oct.| Nov. | Dec.| Jan, | Feb. |Mar,| April, |May,| June. |July,} Aug.|Sept.| Oct.} Nov, | Dec, | Mean, 









———— |§ | ce, | 
diy, | div. | div,| div. | div.} div. diy. | div.| diy, diy. | div. diy, | diy, | div. | div. | div. div, div, 
Sunrise .. |15*7| 26*1]17*4] 105°0 | 407] 127°0 | 93°9 |23°6] 42°0|11°1) 127 | 17*3] 25°8| 19°3] 24:9) 59°3 | 116°5 | 46-1 
9 a.m....|34'2/57°0| 73'9| 188°6 | 77°3] 173°1 | 189°3 | 96°0) 128'4 | 30°8] 24°9 | 38°5] 38°1| 57°4) 43°3] 138°7 | 175°8 | 91°5 
3 p.m....|18°0 26°9]29°5| 86°6 | 64°8) 142°6 | 151°5 | 35°8| 33:8] 12°0} 18°1 | 20°83) 23°8) 35*1) 38-4] 66°1 | 204°8 | 6o'9 

Sunset ..|38°0| 49°2| 44°0) 164°8 | 58°7| 173°1 | 156°5 | 48°7| 39°3 | 32°71] 34°6 | 38°3] 40°1/ 46°3| 56°38) 58°6 | 225°0 | 76-9 





Mean... ..|26°4| 39°9) 41°3} 136°5 | 60°4| 153°4 | 147°5 |51°2| 60°7 |21°5| 22°6 | 28-8) 32°0| 39°7| 40'7| 81°0 | 180°0 68'9 






The numbers expressing the mean electrical tension of each month exhibit 
very clearly a mean annual period, which may be advantageously compared 
with the annual periods already deduced; for this purpose the four annual 
periods derived from various sources are included in the following table. 
TABLE LXXVIII. 
Comparison of the annual periods of the electric tension derived from various 
sources. 

Annual period. Jan. | Feb. |Mar.| Apr.|May.|June. Suly.|Aug. Sep. (Oct. Nov.| Dec. |Mean. 

ac | a | a | | a | i | | | | a 



diy. | div. | div. | div. | div. | div div. | div. | div. | div. | div. | div. | div. 
Sunset, 5 years ...... 171°2 |124°8 |85°6 |68-2 |51°3 | 42-2 [44:0 |39°3 |44°6 [54 8 |87°1 [127-4] 78:4 
3 years, 1845 to 1847./150°7 |166°6 |75-0 |57°2 37-9 29°3 |38°8 |29°4 |33°0 [50° 69:6 |109'5 | 66:9 
Sunrise, 5 years ...... 118°3 | 7771 |51:0 |39°4 |27°5 | 18°6 |25-1 |20°3 |22°4 |27°5 |59-3 | 71°6| 46:8 
The year 1844......... 153:4 |147°5 [51:2 |60°7 215 22°6 |28°8 (32:0 |39°7 40-7 81:0 |180:0| 71:8 
Upon comparing the annual period deduced from the four daily readings, 
in the year 1844, with those recorded in Table LIV., we find the same irre- 
gularity of movement which characterized each of those deduced from the 
twelve daily readings in 1845, 1846 and 1847. The contrast in this respect 
with the smoothness and regularity in the general flowing of the curves, 
derived from five years’ observations, appears to indicate that this is the 
shortest term in which the effects of accidental influences may be efficiently 
eliminated, so as to exhibit the annual progression of the electric tension, 
either in immediate connexion with, or following at some definite interval, 
the annual progression of the humidity of the atmosphere. We have already 
alluded to the protuberance on the upward branch of the sunrise curve, as 
resulting from a higher tension than ordinary in the month of November 
1843 (see p. 162). The fifth column (Nov.) in Table LX XVII. exhibits the 
extraordinary character of this month, and shows that the electric tension 
was developed with increased force at each of the observation-epochs: this 
is very apparent from the comparison of this month with the remaining No~« 
vembers, and from it we may infer, that upon five years’ observations, the 
tension of November being of the ordinary character, the annual curve is 
likely to present a smooth and gently flowing contour. In the table before 
us the features of the summit of the annual curve are well-marked: we have 
already alluded to the acuminated and symmetrical character of the summit 
of the sunset curve (see p. 160). This is amply borne out by the annual curve 


