ON ELECTRICAL OBSERVATIONS AT KEw. 143 
4 a Previous to examining the summer 
1 1 . . . . 
PP ty ie 0 he curves of high tension, it will be de- 
sirable to direct our attention to those 
of the winter ; two circumstances con- 
tribute to this mode of proceeding. 
In discussing the curves of low ten- 
sion, we found the greatest approach 
to a single progression occurring in 
the winter, and this would suggest 
that in the same season we ought to 
find the most decided development of 
the two maxima in the curves of high 
tension, which give to the aggregate 
curves the feature of a double pro- 
gression, The great majority of read- 
ings during the summer being below 
60 div., those above will be consider- 
ably less in number than the high 
readings in the winter, and it is con- 
sequently to be expected that the 
movements of the high tensions (sim- 
ply considered as such) will be much 
more irregular in the summer than in 
the winter: in a word, if we can at 
all find any unequivocal indications 
of regularity of movement among the 
high tensions, weare much more likely 
to find them in the winter than in the 
‘summer. 
Diurnal period above 60 div., Win- 
ter.—The entire number of high read- 
ings, 2647, is thus divided :-— 
1845. Mean. 
1846,— Mean, 
1847. Mean. 
3 years. Mean. 
Winter’ Zoos ccc ceeses 1979 
Summer ............ 668 
2647 
The following table exhibits the 
distribution of the winter observations 
over the twelve observation-hours : — 
Mean diurnal curve of the electrical tension above 60 diy. for the years 1845, 1846 and 1847, with the mean curve of the three years. 
4 A.M. 10 a.m. 10 P.M. 2 A.M. 
E 4 
a =) 
Taste XLI. 
Number of positive readings above 60 div. at each observation-hour in the 
three winters of 1845, 1846 and 1847. 
” 
a 
he 







——_—-— 
66 84 64] 68} 74] 83] 88 96 | 625 
81 93 “1| 77| 76} 93} 92] 107 | 696 
80 91 66 | 67| 70} 83] 94] 104 | 658 
| | | | | 
PUESs|ovneus| nevces | ensue 11 | 227 | 268 | 201 | 212 | 220 | 259 | 274 | 307 |1979 





7 Y “It will be seen from these numbers that the distribution of readings some- 
what assimilates to that of the entire year, being more numerous about the 

