116 REPORT—1849. 
Tasce I. 
Unemployed positive readings. 



Div. Div. 
Volta No. 1. Date. Volta No. 1. 
1845. Feb. 23, 8 a.m. | 2000 1846. June 25, 2 p.m. | 4500 
1845. May 20, 8 p.m. | 3000 1846. Aug. 1, 4 p.m. | 5500 
1845. May 26, noon. 4.500 1846. Aug. 1, 6 p.m. | 5500 
1845. June 4,2 p.m. | 3500 || 1846. Aug. 3, noon. | 1500 
1845. July 11, 2 p.m. | 2000 || 1846. Aug. 5, Gam. | 3000 
1845. Aug. 7, 2p.m.| 1000 | 1847. Mar. 10, 4 p.m. | 2500 
1845. Aug. 7, 4 p.m. | 2000 1847. Apr. 29, 4 p.m. | 2500 
1846. Feb. 27, noon. | 2000 1847. Apr. 29, 6 p.m. | 1000 
1846. Mar. 26, 6 p.m. | 4500 1847. Apr. 30, 2 p.m. | 2500 
1846. Apr. 25, 2p.m.| 3000 || 1847. May 3, 2p.m.| 3000 
1846. Apr. 26, 6 am. | 2000 1847. July 17, 6 am. | 2000 
1846. May 6, 2p.m.| 4500 1847. July 17, 8am. | 3500 
1846. May 20, 2 p.m. 5000 1847. Dec. 30, noon. 2000 




Diurnat PErRIoD. 
Diurnal period. Year.—In examining the results obtained from a dis- 
cussion of the positive observations, it will be desirable to confine our atten- 
tion first to the diurnal period of the electrical tension, or to those variations 
exhibited by the electrometers which have a day for the period in which they 
are completed, and which evidently depend on, or are connected with, the 
rotation of the earth on its axis. 
The 10,176 observations upon which the mean diurnal period of the three 
years is based, are thus distributed among the twelve daily readings. 
Tasxe II. 
Number of positive readings at each observation-hour in the three years 
1845, 1846 and 1847. 
be OE Oia! a Soe a Oe ee ee eee 
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 | 246 | 190 | 341] 327 | 275 | 297 | 302 | 304 | 302 | 332.) 3374 
1846.| 234] 257 | 269 | 190 | 353] 338 | 288 | 278 | 287 | 281 | 286] 338 | 3399 
1847.| 199] 255 | 289 | 186 | 353] 348 | 285 | 283 | 289 | 289 | 290] 337 
3403 


It will be remarked, that the greatest number of positive observations 
were recorded at 8 a.m., and the least number at 6 A.M. The numbers from 
noon to 8 p.m. do not vary materially in amount; but at 10 p.m. the number 
again increases. By consulting the following table of the distribution of 
negative observations, it will be seen that the greatest number occurred be- 
tween 8 A.m. and 8 p.m. exclusive; this will to some little extent account for 
the difference; but the principal cause is, that on Sundays the observations 
were suspended between 10 a.m. and 10 p.m. exclusive. The small number 
of observations at 6 A.m. arises from the fact, that during the winter months, 
the personal observations were not commenced until 8 A.M., or more pro- 
perly speaking until sunrise. ’ 

