
ee a 
1846, 
1847, 
3 years,— 
A. 

ON ELECTRICAL OBSERVATIONS AT KEw. 157 
Mean, 
In the Tables LXII. LXIII. and LX 
5, 1846 and 1847, with the mean curve of the three years. 
Mean annual curves of the electric tension above 60 div. for the years 184 
IV. the annual period is very apparent, 
but it exhibits a much greater irregu- 
larity of movement, both in the indivi- 
dual yearsand inthe mean of the three, 
than the annual periodasdeduced from 
all the observations. This irregularity 
of movement is well seen in the an- 
nexed curves (fig. 16), as well as the 
character which the high readings 
impart to the aggregate curves ; for 
on comparing these with the aggre- 
gate curves on page 152, it will be 
observed that the latter present all 
the essential features of the curves of 
high tension, but so subdued that 
the movements appear more gentle 
and regular. In fact, throughout the 
series (excepting the summer months ) 
the curves of high tension materially 
influence those as deduced from ail 
the observations, and lead to the con- 
clusion, that either throughout the 
year or during the winter, upon the 
supposition of high readings more 
directly measuring the electrical ten- 
sion of aqueous vapour, the presence 
of such vapour materially affects the 
results. The same thing holds good 
with regard to the summer curves; 
for although the curves of high ten- 
sion in the summer are very ano- 
malous, yet the difference between 
the summer and winter curves of low 
tension, and the greater similarity 
between the aggregate and low ten- 
sion summer curves, combined with 
the dissimilarity between the aggre- 
gate and low tension winter curves, 
strongly suggest that the summer low 
tension, as well as the aggregate 
curves, are materially influenced by 
the vapour, from the effects of which, 
as before observed, it is desirable the 
curves exhibiting the diurnal and 
annual march of electricity should be 
freed. 
