170 a2 REPORT—1849, 
tities are consequently reversed. It is worthy of remark that, while both the 
Decembers present single progressions, the points of maxima occur at different 
periods of the day. The very close approximation of the values of the means 
of the seventeen months, with opposite signs at sunrise and 9 a.m. and at 
3 p.m. and sunset, is very interesting, and strongly indicates a symmetrical 
disposition of the epochs of mean‘ tension, as deduced from these four daily 
readings with regard to them. We have, in fact, a tension at 9 a.m. as much 
above the mean as that at sunrise is below it, and the same thing occurs at 
3 p.M. and sunset, the value being rather more than one-third of the move- 
ments in the morning. The great accordance which exists in this respect 
with the results already arrived at is interesting, and tends greatly to confirm 
the deductions that the movements are much greater in the morning and 
forenoon, that the depression in the afternoon is of a minor character, and 
that the principal maximum occurs in the evening; for although the mean 
tension at sunset is dower than that at 9 a.m. (see Table LXXVII.), yet the 
occurrence of two winters in the seventeen months tends to place the epoch 
of sunset nearer the afternoon minimum than it is upon the year. It should 
be borne in mind, that as the epochs of sunrise and sunset are variable, those 
of mean tension must be symmetrically disposed with regard to the mean 
epochs of sunrise and sunset, and 9 A.M. and 3 P.M. 
High tensions.—Of the 1346 observations in the year 1844 that contri- 
bute to the results deduced for that year, 180 belong to the class of high 
tensions. The two following tables exhibit the distribution and limits of 
value of these readings. 
Taste LXXXI. 
Number of positive readings (high, or above 60 div.) at each observation- 
epoch in each month of the year 1844, 








Month. Sunrise.| 9 a.m. | 3 p.m. | Sunset. | Sums. 
January .... 8 6 8 ci 29 
February ..| 11 9 5 6 31 
March .... 4 3 sic 1 8 
REO so | 2 5 5 I mee ee 
Madye2.9.!. ‘ 1 ‘ 1 2 
June .... 
July oe 
August .. 
September .. 2 2 505 one 4 
October .... 2 1 1 1 5 
November ..| 11 13 1 6 37 
December ..| 12 13 14 14 sey 

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