ATMOSPHERIC MAGNETISM 
83 
Washington, U.S — Longitude 77° 2' West. Latitude 38° 54' North. Mean declina- 
tion 1 ° 25' West. Mean dip 71 ° 20' North. 
Mean Diurnal variation of the Declination in minutes, and temperature in Fahren- 
heit’s scale, of the months of the years 1840, 1841, 1842, which are specified. 
Increasing numbers denote a movement of the south or upper end towards the East. 
Mean time 
Noon, 
h m 
0 13 
h m 
3 13 
h m 
4 13 
h m 
6 13 
h m 
8 13 
h m 
10 13 
h m 
13 13 
h m 
14 13 
h m 
16 13 
h m 
18 13 
h m 
30 13 
h m 
33 13 
Mean. 
January 1841-43 
4-10 
5-30 
3-96 
3-53 
6-87 
6-68 
1-01 
1-63 
1-66 
1-71 
6-91 
6-39 
3-04 
February 1841-43 
3-55 
5-38 
4-33 
3-89 
1-59 
0-94 
0-84 
1-36 
0-81 
0-83 
0-60 
0-35 
1-76 
March 1841-43 ... 
6-34 
7-51 
6-36 
4-35 
3-88 
3-31 
3-50 
3-00 
1-71 
1-13 
0-00 
1-76 
3-30 
April 1841-43 ... 
6-56 
8-33 
6-43 
4-41 
3-33 
1-97 
3-34 
1-35 
0-73 
0-46 
0-00 
3-18 
3-15 
May 1841-43 
7-72 
8-57 
6-36 
4-45 
3-83 
3-47 
3-35 
3-05 
3-63 
0-33 
0-00 
4-35 
3-99 
June 1841-43...... 
8-55 
9-47 
8-00 
5-33 
4-91 
4-34 
4-05 
4-33 
3-44 
0-63 
0-00 
4-53 
4-79 
July 1840-41 
8-43 
9-87 
8-07 
5-75 
4-57 
3-53 
3-60 
3-40 
3-99 
0-98 
0-00 
3-63 
4-56 
August 1840-41... 
10-94 
10-81 
7-95 
6-00 
4-03 
3-55 
4-48 
4-64 
4-04 
1-35 
000 
5-89 
5-30 
Sept. 1840-41 
8-76 
8-44 
5-43 
4-45 
3-63 
3-31 
3-83 
3-86 
3-44 
0-87 
0-00 
4-33 
3-85 
October 1840-41 
5-65 
5-83 
4-35 
3-47 
1-41 
0-58 
1-41 
1-80 
1-51 
1-35 
0-00 
1-75 
3-34 
Nov. 1840-41 
4-69 
4-79 
3-33 
1-60 
0-51 
0-74 
1-14 
1-41 
0-83 
0-71 
0-00 
1-83 
1*79 
Dec. 1840-41 
3-93 
4-90 
3-39 
1-92 
0-10 
0-36 
0-63 
1-53 
0-93 
3-00 
1-03 
0-87 
1-79 
Temperature, 
Mean time 
Noon, 
h m 
0 13 
h m 
3 13 
h m 
4 12 
h m 
6 12 
h m 
8 13 
h m 
10 13 
h m 
13 13 
h m 
14 13 
h m 
16 12 
h m 
18 12 
h m 
30 13 
h m 
32 12 
January 1841-43 
38-38 
40-83 
40-18 
3§-68 
35-47 
34-34 
33-37 
33-10 
31-71 
30-53 
31-63 
3^-96 
February 1841-43 
40-03 
43-51 
42-28 
38-23 
35-38 
33-86 
33-58 
31-33 
30-51 
30-18 
31-44 
36-72 
March 1841-43 ... 
51-39 
53-61 
53-28 
49-96 
46-30 
44-37 
43-48 
41-36 
40-06 
39-87 
43-28 
48-06 
April 1841-43 ... 
57-68 
59-81 
60-20 
57-21 
53-18 
49-12 
47-91 
46-91 
46-13 
46-49 
49-93 
54-02 
May 1841-43 
66-37 
68-48 
68-69 
65-93 
59-83 
56-70 
55-19 
53-34 
53-43 
55-50 
59-72 
63-23 
June 1841-43 
79-33 
81-85 
82-75 
76-89 
72-39 
68-70 
66-83 
66-04 
65-07 
68-26 
73-63 
77-37 
July 1841 
81-13 
81-53 
84-60 
81-33 
74-93 
71-56 
68-78 
68-09 
66-78 
70-64 
75-19 
78-38 
August 1840-41... 
78-70 
80-73 
80-09 
75-93 
71-48 
68-00 
66-83 
65-12 
64-17 
65-69 
65-73 
76-09 
September 1841 ... 
74-66 
76-50 
76-30 
72-30 
68-59 
64-90 
63-70 
61-90 
61-00 
61-29 
65-73 
71-03 
October 1841 
55-30 
57-00 
56-20 
52-94 
48-40 
46-60 
44-90 
43-70 
43-30 
41-70 
45-00 
51-61 
November 1841 ... 
48-00 
49-30 
48-50 
47-30 
44-30 
43-30 
41-80 
40-70 
39-40 
38-80 
39-50 
44-10 
December 1841 ... 
39-20 
41-30 
40-60 
37-95 
36-36 
34-70 
33-50 
33-16 
33-20 
31-60 
31-69 
36-00 
