144 
MR. J. F. MILLER ON THE RELATION BETWEEN THE 
culated, arranged and printed, at his own cost, an elaborate series of tables, showing, 
at a glance, the relation of the temperature of evaporation to that of the dew-point at 
every degree of the air temperature, from 10° to 90°; also the elastic force of vapour, 
weight of vapour in a cubic foot, the remaining quantity required for complete satu- 
ration, the relative degree of humidity, and the weight in grains of a cubic foot of 
air, under the varying conditions of heat, of humidity and of pressure. 
Notwithstanding a conviction of the accuracy of Mr. Glaisher’s tables, both from 
the well-known character of the chief observer and compiler, and the favourable 
circumstances under which the elements were obtained, yet having found similar 
tables defective, and having used Daniell’s apparatus with satisfaction for many 
years, I felt reluctant to abandon it for the wet- and dry-bulb thermometers, slight as 
is the trouble of observing them, without personal experience of the correctness of 
the tables by which the dew-point was to be eliminated. 
Accordingly, I sent up my Daniell’s hygrometer to Greenwich for comparison 
with the observatory standard thermometer, and, at the same time, Mr. Glaisher 
kindly procured me a pair of delicate thermometers on the same metal frame, selected 
from a number of others, and made by Barrow of Oxenden Street. These thermo- 
meters were considered to have identical readings under similar circumstances, and 
both to agree with the Greenwich standard. The dew-point thermometer was also 
found to be generally correct, the errors mostly amounting to small fractions of a 
degree. 
With these instruments the observations embodied in the annexed Tables were 
made in the years 1847 and 1848, the hours of observing being 11 o’clock in the 
morning, and 3 o’clock in the afternoon. 
Ilygrometrical state of the Atmosphere at Whitehaven, in the year 1847. 
Dry bulb. 
Wet bulb. 
Dew-point. 
Deduced 
Observed. 
1847. 
11 A.M. 
3 P.M. 
Mean. 
11 A.M. 
3 P.M. 
Mean. 
Compt. of dew-point. 
11 A.M. 
3 P.M. 
Mean. 
11 A.m. 
3 P.M. 
Mean. 
11 A.M. 
3 P.M. 
Mean. 
0 
0 
0 
0 
Januaiy 
36-64 
38-61 
37-62 
32-50 
33-82 
33-16 
4-14 
4-79 
4-46 
February 
37-17 
39-64 
38-40 
31-14 
3-2-10 
31-62 
6-03 
7-54 
6-78 
March 
43-13 
46-34 
44-88 
36-03 
36-09 
36-06 
7-10 
10-25 
8-82 
April 
45*68 
47-75 
46-71 
38-55 
39-53 
39-04 
7-13 
8-22 
7-67 
May 
55-70 
57-23 
56-46 
51-46 
52-82 
52-14 
48-40 
49-50 
48-95 
47-96 
49-25 
48-60 
7-74 
7-98 
7-86 
June 
59-85 
61-75 
60-80 
54-96 
55-63 
55-29 
51-50 
51-00 
51-25 
51-43 
50-98 
51-20 
8-42 
10-77 
9-60 
July 
64-98 
67-46 
66-22 
59-96 
61-36 
60-66 
57-00 
57-80 
57-40 
57-11 
57-66 
57-38 
7-87 
9-80 
8-84 
August 
61-53 
62-70 
62-11 
56-87 
57-56 
57-21 
53-90 
53-78 
53-84 
53-95 
53-78 
53-86 
7-58 
8-92 
8-25 
September 
55-03 
56-26 
55-64 
50-96 
51-11 
51-03 
48-20 
47-30 
47-75 
47-82 
46-68 
47-25 
7-21 
9-58 
8-39 
October 
54-09 
53-82 
53-95 
50-88 
50-37 
50-62 
48-20 
46-80 
47-50 
48-02 
47-04 
47-53 
607 
6-78 
6-42 
November 
49-85 
50-50 
50-17 
47-59 
48-26 
47-92 
45-40 
46-00 
45-70 
45-57 
45-87 
45-72 
4-28 
4-63 
4-45 
December 
41-58 
41-28 
41-43 
39-61 
3923 
39-42 
37-00 
36-80 
36-90 
37-18 
36-71 
36-94 
4-40 
4-57 
4-49 
Means 
50-43 
51-94 
51-20 
51-53 
52-04 
51-78 
48-73 
48-62 
48-66 
43-93 
44-12 
44-03 
6-50 
7-82 
7-17 
Mean of observed dew-point 
48-56 
From May ... 
48-56 
