ON ELECTRICAL OBSERVATIONS AT KEW. 113 
Report on the Discussion of the Electrical Observations at Kew. 
By Wiuuiam RavcuirF Brrr. 
Tux clectrical observations made at the Observatory of the British Associa- 
tion at Kew from August 1, 1843, to August 8, 1848, are divisible into two 
portions, one occupying a period of seventeen months, viz. from August 1843 
to December 1844 both inclusive, during which the readings were taken at 
sunrise, 9 A.M., 3 P.M. and sunset; the other, a period of three years and 
seven months, viz. from January 1844 to July 1848, also inclusive, during 
which the readings were taken at each even hour of Greenwich mean time 
as well as at sunrise and sunset. The last portion, which is by far the most 
complete, furnishes, from the observations of three complete years, the materials 
for deducing the diurnal and annual periods of the electrical tension. This 
has accordingly claimed our first attention and forms the first section of 
Part I., which is exclusively devoted to the examination of Positive Electricity. 
The observations at sunrise and sunset, extending over the entire period 
of the five years, from the variability of the epoch of observation, require a 
separate discussion ; they accordingly form the subject of the second section ; 
and the third section is occupied with a discussion of the observations during 
_ the first seventeen months. 
Scattered over the entire period of the five years we have several readings 
of negative electricity, and as they are evidently accompanied by meteorolo- 
gical phenomena of a peculiar and unmistakeable character which strongly 
indicate them to be the results of disturbances, rather than their forming any 
portion of a regular progression of the electric signs, they have also been 
separately discussed. Their discussion forms Part IL. of this Report. 
Part I.—POSITIVE ELECTRICITY. 
Section 1—Discussion of Positive Readings during the Years 1845, 1846 
and 1847. 
During the years 1845, 1846 and 1847, 10,526 observations were recorded 
in the Journal, including the indications of the night-registering apparatus. 
Of these— 
10,176 were positive ; 
324 ,, negative, and 
26 ,, not employed in the discussion ; 
10,526 
In the following table are recorded the twenty-six unemployed readings 
which were positive; they were in almost every case either preceded or suc- 
ceeded by negative readings, from which it was concluded that they resulted 
more from a disturbance in the usual electrical condition of the atmosphere, 
than that they formed a part of its regular diurnal march: from these cir- 
cumstances, connected with the high tensions mostly exhibited, it was appre- 
hended the results would have been materially affected by employing them 
in the investigation. 
In the following discussion, readings occasionally higher than some of those 
em below have been employed, but they have evidently formed either 
49, I 
