200 
FIFTH REPORT— 1835. 
Table XII.—Showing the Hours of Morning and Evening when 
the Mean Temperature of Spring, Summer, Autumn, and Win¬ 
ter occurs in each season, as deduced by Table YII. 
Mean of 
1833 and 1S34. 
Spring. 
Summer. 
Autumn. 
Winter. 
h 
ra 
h 
m 
h 
m 
h m 
A.M. 
8 
1 
7 
33 
8 
26 
9 18 
P.M. 
7 
1 
7 
21 
6 
25 
6 30 
Table XIII.—Showing the Hours of the Morning and Even¬ 
ing when the Mean Temperature of Summer and Winter oc¬ 
curs in each season, as deduced by Table YIII. 
Mean of 
1834 and 1834. 
Summer. 
Winter. 
h 
m 
h m 
A.M. 
7 
48 
8 50 
P.M. 
7 
9 
6 37 
Relation of the Mean Temperature of each Hour , and each 
similar pair of Hours, to the Mean Annual Temperature , 
or Mean Temperature of the whole Twenty-four Hours , as 
deduced by Table YI. 
It appears from the Hourly Registers at Plymouth and at 
Leith, that any number of daily observations of the thermome¬ 
ter seldom give a correct mean result without corresponding 
observations at night. The deviation with three observations in 
the day, is nearly three times as great as that arising from only 
two observations taken at any similar pair of hours. We gain, 
therefore, very little by multiplying daily thermometric obser¬ 
vations without reference to some general principle of guidance. 
Hence the importance of determining, by experiment in differ¬ 
ent places, the relation between the mean temperature of the 
twenty-four hours and that of any single hour, or any similar 
pair of hours. In the following table will be found the mean 
temperature of each hour for the years 1833 and 1834, with the 
deviations of each from the mean of the whole year, or of the 
twenty-four hours, as deduced by Tables II. and IV., as also that 
of the mean temperature and deviations of each hour for the 
two years together, as deduced by Table VI. 
