142 REPORT—1849, 
‘periods, each being marked by a greater number of readings than the inter- 
mediate period between them. Of these, the last, viz. that occurring at 6, 8 
and 10 p.M., presents the greatest number of observations, and it is to be no- 
ticed, that both periods coincide with the epochs of the forenoon and even- 
ing maxima, as developed in the aggregate curves. This of itself indicates 
that the greatest number of high readings occur at those epochs, and that 
the maxima result more from a systematic occurrence of the high than the 
low readings. ‘There is a difference between the greatest number, 473, at 
10 p.m., and the smallest (excluding 4 and 6 A.M.), 221, at noon of 252. 
TABLE XXXIX. 
Mean electrical tension above 60 div. at each observation-hour in the three 
years 1845, 1846 and 1847, with the mean diurnal period as deduced from 
the whole. : 
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. 






LE ae 85-0 |116°7 167-7 | 205°6 |173°7 |144°3 |130-2 |146°0 |187°9 | 205°8 |173°2 
MOOR; cores] snaree 72°5 |123°9 |122°2 | 153-2 |176°3 |147°6 {137-2 1163-9 |162°1 | 146°2 |149°7 
LG a ae 70°8 |110°0 |164°7 | 219°6 |244°9 |249-°2 |215°5 |222°8 |204°4 | 191°6 |205°6 
Aiea intel Vs casy 76°6 |116:2 |150°5 | 192-2 |197°8 |178°6 |159°6 |175°8 |184°3 | 181°5 |175°9 
TABLE XL. 
Excess or defect of the mean electrical tension above 60 div. at each ob- 
servation-hour, as compared with the mean of the year for the three years 
1845, 1846 and 1847, and the mean diurnal period. 





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. diy, div. | div. | diy. | div, | div. 
—|/-—|-| + )+]-]-|-] +4] + 
E840.) oeoas| popes 88°2/56°5 | 5:5 | 32-4 | 0-5 | 28-9 | 43-0-] 27-2 | 14-7 | 32°6 [173-2 
—-|-|-]|+]+]-]-]+] 4 
nice LR Ma Ses 77:2|25°8 |27°5 | 3°5 | 26°6 | 21 |12°5 | 14-2 | 12-4 
—~}|/—|-—j| +] +] +} 4+] +] - 
UB 4G Hes daliaxseop 134°8 | 95:6 |40°9 | 14:0 |39°3 | 43°6 | 9°9 |17:2 | 1:2 




—~|/-}|-]| +]/4+/4+]-/]- 
Mean.]}......!...s-. | 99°3|}59°7 |25°4 | 16:3 | 21°9 | 2:7 |163 | O-1 

Although the movements, as exhibited in the above tables, are decidedly 
irregular, yet the indications of a double progression are by no means deficient ; 
they appear very prominently in the period for the year 1845. In this year 
the rise is very regular until 10 a.m., after which a fall, quite as regular, takes 
place between 10 A.M. and 4 p.M., and then the tension increases quite as re- — 
gularly until 10 p.m. In 1846 and 1847 these movements are not so distinet, 
especially in the latter year, in which a great tendency to a single maximum 
about 2 P.M. occurs; there is however a subordinate maximum at 6 p.M. In 
1846 the two maxima are developed, the forenoon being the principal. The 
mean curve of the three years exhibits a period of tolerable regularity, in 
which the two maxima are well-marked, that of the forenoon being the highest; 
the epochs are noon and 8 P.M. 
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