APPLIED TO METEOROLOGICAL OBSERVATIONS. 
137 
Table XI. — Showing the corrections to be applied to the monthly mean value of the 
degree of humidity at the height of four feet above the soil at any hour, to deduce 
the true degree of humidity for the month from the observations at that hour. 
Local 
mean time. 
January. 
February. 
March. 
April. 
May. 
June. 
July. 
August. 
Sept. 
Oct. 
Nov. 
Dec. 
Midnight. 
— 0-013 
— 0-021 
-0-063 
— 0-095 
0-087 
— 0-105 
— 0-091 
-0-096 
0-080 
0-053 
0-018 
0-011 
1 A.M. 
4-0-002 
— 0-021 
— 0-065 
— 0-106 
— 
0-100 
— 0-114 
-0-095 
— 0-104 
— 
0-080 
0-059 
— 
0-009 
— 
0-012 
o 
4-0-004 
— 0-026 
-0-066 
-0-116 
— 
0-108 
— 0-125 
— 0-107 
-0-113 
— 
0-085 
0-066 
— 
0-011 
— 
0-017 
3 
— 0-003 
— 0-033 
-0-067 
— 0-123 
— 
0-113 
— 0-132 
-0-116 
— 0-117 
— 
0-091 
— 
0-070 
— 
0-020 
— 
0-019 
4 
— 0-013 
— 0-036 
-0-068 
— 0-126 
— 
0-114 
-0-138 
-0-120 
— 0-123 
— 
0-097 
_ 
0-075 
— 
0-030 
— 
0-024 
5 
-0-019 
-0-035 
-0-066 
— 0-125 
— 
0-106 
-0-139 
— 0-120 
— 0-123 
— 
0-098 
— 
0-077 
— 
0-030 
— 
0-024 
6 
-0-021 
— 0-034 
— 0-063 
— 0-112 
— 
0-085 
-0-107 
-0-097 
-0-107 
— 
0-097 
— 
0-071 
— 
0-033 
— 
0-026 
7 
— 0-020 
-0-030 
— 0-055 
— 0-080 
— 
0-059 
— 0-065 
— 0-055 
-0-061 
— 
0-080 
— 
0-058 
— 
0-031 
— 
0-025 
8 
— 0-020 
-0-020 
-0-035 
— 0-065 
— 
0-024 
-0-015 
-0-005 
— 0-020 
— 
0-047 
— 
0-037 
— 
0-021 
— 
0-018 
9 
—0-017 
— 0-007 
-0-003 
— 0-034 
+ 
0-018 
+ 0-035 
+ 0-041 
+ 0-030 
0-000 
— 
0-009 
— 
0-008 
— 
0-007 
10 
-0-004 
4-0-009 
+ 0-031 
— 0-015 
+ 
0-051 
+ 0-078 
+ 0-080 
+ 0-070 
+ 
0-042 
+ 
0-025 
+ 
0-008 
+ 
0-008 
11 
4-0-011 
+ 0-028 
+ 0-060 
+ 0-022 
+ 
0-083 
+ 0-100 
+ 0-104 
+ 0-102 
+ 
0-082 
+ 
0-060 
+ 0-027 
+ 
0-022 
Noon. 
4-0-031 
+ 0-045 
+ 0-084 
+ 0-070 
+ 
0-110 
+ 0-123 
+ 0-114 
+ 0-127 
+ 
0-115 
+ 
0-088 
+ 
0-040 
+ 
0-033 
1 P.M. 
4-0-054 
“}~ 0*0o8 
+ 0-100 
+ 0-132 
+ 
0-126 
+ 0-137 
+ 0-119 
+ 0-142 
+ 
0-131 
+ 
0-109 
+ 
0-050 
+ 
0-046 
2 
■40-059 
+ 0-065 
+ 0-106 
+ 0-151 
+ 
0-125 
+ 0-135 
+ 0-123 
+ 0-145 
+ 
0-132 
+ 
0-113 
+ 
0-054 
+ 
0-048 
3 
4-0-048 
+ 0-065 
+ 0-104 
+ 0-147 
+ 
0-118 
+ 0-123 
+ 0-121 
+ 0-138 
+ 
0-126 
+ 
0-108 
+ 
0-047 
+ 0-036 
4 
4-0-036 
+ 0-053 
+ 0-087 
+ 0-128 
+ 
0-108 
+ 0-113 
+ 0-111 
+ 0-120 
+ 
0-103 
+ 
0-089 
+ 
0-032 
+ 
0-024 
5 
4-0 021 
+ 0-032 
+ 0-063 
+ 0-110 
+ 0-091 
+ 0-099 
+ 0-095 
+ 0-100 
+ 
0-071 
+ 
0-055 
+ 
0-018 
+ 
0-013 
6 
4-0-007 
+ 0-009 
+ 0-038 
+ 0-088 
+ 
0-074 
+ 0-078 
+ 0-062 
+ 0-071 
+ 
0-044 
+ 
0-030 
+ 
0-005 
+ 
0-004 
7 
— 0-005 
-0-010 
+ 0-010 
+ 0-059 
+ 
0-052 
+ 0-049 
+ 0-025 
+ 0-036 
+ 
0-009 
+ 
0-007 
— 
0-005 
— 
0-003 
8 
- 0-014 
-0-023 
— 0-010 
+ 0-020 
+ 
0-022 
+ 0-010 
— 0-015 
0-000 
— 
0-015 
— 
0-011 
— 
0-012 
— 
0-005 
9 
— 0-016 
-0-029 
-0-032 
— 0-030 
— 
0-018 
-0-025 
-0-040 
— 0-038 
— 
0-040 
— 
0-025 
— 
0-017 
— 
0-007 
10 
-0-019 
— 0-030 
— 0-048 
— 0-058 
— 
0-050 
— 0-060 
-0-068 
— 0-067 
— 
0-058 
— 
0-039 
— 
0-020 
— 
0-008 
11 
— 0-018 
-0-036 
-0-060 
— 0-080 
— 
0-075 
— 0-085 
-0-080 
— 0-085 
— 
0-071 
— 
0-048 
— 
0-020 
— 
0-009 
The sign + denotes that the number is to be added, and the sign — denotes that the number is to be subtracted. 
When evaporation commences in the morning with the increase of temperature, 
the vapour seems to accumulate on the surface of the soil, till the air in its vicinity 
becomes heated, and the daily ascending current of air commences. It seems likely 
that this stratum of vapour neither attains a great thickness nor spreads upwards till 
the ascending current takes place, and that it ascends and spreads as long as the 
ascending current continues. 
In summer time, between the hour of noon and that of the maximum temperature 
of the air, the temperature of the dew-point remains nearly stationary*, and the de- 
gree of humidity becomes less in value notwithstanding that evaporation is the most 
rapid. It is evident, therefore, that all the water evaporated must at once pass up- 
wards. The strength of the ascending current of air being at a maximum at the 
same time that the stream of vapour is the most rapid, it would seem that the rapidity 
of motion of the latter is dependent on the former. Towards the evening hours, when 
the temperature of the air is decreasing rapidly, the ascending current will decrease 
in force, and ultimately cease altogether, giving place to the descending current of 
night ; then the vapour again accumulates on the surface of the earth, not only from 
evaporation, but also from the vapour flowing down with the descending current, 
the air more and more nearly approaches to a state of saturation, and the degree of 
humidity of the air arrives at its maximum. 
* See remarks following Table VIII. 
MDCCCXLVIII. 
T 
