138 REPORT—1849. | 
This subdued character of the two maxima, as well as the comparatively 
slight depression of the included minimum, is well seen in the above table ; 
and when combined with the characters of the individual curves of each 
winter which have been noticed above, together with the approach of the 
epochs of maxima in the mean curve to each other, viz. from 10 A.M. to noon, 
and from 10 P.M. to 6 P.M., a strong probability is suggested, that were we 
able effectually to separate the high from the low tensions, not at an arbitrary 
point, but in such a manner that the high tensions of summer (in all proba- 
bility lower than those of winter) should find entry in their respective de- 
partment, the result would be, that the low tensions would exhibit a single 
progression in harmony with the temperature. 
In the following table the diurnal periods for the winter, as deduced from 
the aggregate and low tensions, are placed in contrast. 
TaBLe XXXIII. 
Comparison of the excess or defect from the mean of the diurnal periods 
of winter, as deduced from the aggregate observations and from those be- 
low 60 div. 


Value. |Mid./2 a.m./4 a.m./6 a.m.|8 a.m.|10 ata | Nobu: 2p.m./4 ptt 6 p.m.|8 p.m./10 p.m.} Mean. 

—_— 








div. | div, | div. | div, | div. div. div. | div. | div. | div. | div. div. div. 
—}-|/—-|-|-] 4+ )/+)4+]-|]4+] 4+] + 
Aggregate ..|77°6 | 78°9| 79°4| 55°6) 9:0 27:9 | 13°7| 3°99 | 06 | 27:3) 55°2| 43:4 | 102°] 
—-/-}/-/|-]/-] +.) +) 4+}) 4+] 4] 4) 4+ 
Below60div.| 6°9| 8:2} 8-7) 67| 0:2 36 | 5:7} 4:9 | 52 66| 63] 48 31-4 
Tables XXXIV., XXXV., XXXVI. exhibit the mean electrical tension at 
each observation-hour for each month in the three years 1845, 1846 and 
1847, with the monthly seasonal and yearly means. The characters of the 
monthly movements are exhibited to the eye in the sheets of curves illus- 
trating this report. See Plates VI. VII. and VIII. 
Table XXXVII. exhibits the mean monthly electrical tension at each 
’ observation-hour deduced from the observations of three months, also the 
mean summer, winter, and yearly tension deduced from the observations of 
three summers, winters, and years. ‘The last line in the table, to which the 
word “‘ Means” is prefixed, exhibits the mean tension in each month as de- 
duced from all the separate monthly observations, ¢.e. the mean tension of 
January, 31°5 div. is the result of all the January observations in the three 
years. ‘The same thing holds good of the seasonal and yearly mean tensions. 
The curves projected from these numbers will be found on Plate IX. 
Previous to proceeding with the discussion of the high tensions, it will be 
advantageous to pause, for the purpose of recapitulating the principal points 
that have hitherto come under our notice, and of particularly directing our 
attention to those that stand out prominently from among the others. 
1. We have seen that the discussion of the entire series of the positive 
observations for the three years furnishes us with series of curves, exhibiting 
in a most decided manner a double progression. ‘The points of maxima and 
minima are well-marked, and in most cases they present a tolerable fixity of 
epoch. 
Y. The presence of fog mostly occurring on those occasions when high 
electrical tensions have been observed, combined with the opinion that the 
electricity of serene weather is mostly characterized by /ow tensions, has 
