Horizontal Component of Magnetic Force. 
233 
Variations op the Horizontal Component op Magnetic Force, with reference to the 
Moon's Declination. 
Means of Groups. 
27 days to 1 day, Moon farthest North, 0-000232 13 days to 15 days, Moon farthest South, 0-000218 
2 5 ... 0-000138 16 ...... 19 ... 0-000165 
6 8 ... 0-000134 20 22 ... 0-000213 
9 12 ... 0-000207 23 26 ... 0-000187 
\ 
From these means we may conclude that there are maxima when the moon has its greatest north and south 
declination, and minima when its declination is zero ; the principal minimum occurs when the moon is on the 
equator moving southwards. 
Variations op the Horizontal Component op Magnetic Force, with reference to the 
Moon's Distance from the Earth. 
Means of Groups. 
6 days after Apogee to 6 days before Perigee, 0 000322 
5 days to 2 days before Perigee, . . . 0-000145 
1 day before to 1 day after Perigee, . . 0-000210 
2 days to 5 days after Perigee, . . . 0-000261 
6 days after Perigee to 6 days before Apogee, 0-000191 
5 days to 2 days before Apogee, . . . 0-000205 
1 day before to 1 day after Apogee, . . 0'000235 
2 days to 5 days after Apogee, . . . 0-000240 
TABLE X. — Means of the Bifilar Magnetometer Readings Corrected for Temperature, at the 
Observation Hours for each Month in 1843. 
Month. 
18*. 
201-. 
22 h . 
23 b . 
Oh. 
2 h . 
4 h . 
6>>. 
8>>. 
10>>. 
Sc. Div. 
Sc. Div. 
Sc. Div 
Sc. Div. 
Sc. Div. 
Sc. Div. 
Sc. Div. 
Sc. Div. 
Sc. Div. 
Sc. Div. 
January- 
538-10 
537-95 
533-71 
534-11 
538-80 
540-62 
538-19 
537-11 
537-41 
February 
535-84 
539-04 
533-72 
534-93 
538-23 
540-14 
537-43 
538-34 
537-39 
March 
534-90 
534-22 
528-48 
528-07 
535-96 
540-36 
540-54 
538-30 
537-34 
April 
534-53 
533-37 
524-37 
525-56 
536-19 
543-66 
548-25 
542-26 
536-90 
May 
496-79 
492-82 
486-56 
489-30 
501-94 
506-84 
512-85 
512-56 
501-77 
June 
500-47 
495-70 
488-00 
491-42 
502-11 
508-64 
512-19 
515-87 
510-96 
July 
497-55 
495-32 
486 07 
488-08 
499-48 
512-98 
515-88 
513-74 
506-85 
August 
498-64 
494-37 
487-41 
491-91 
505-11 
512-13 
514-71 
512-69 
511-20 
September 
505-50 
500-25 
491-77 
496-61 
505-57 
512-57 
509-50 
510-72 
509-48 
October 
508-03 
504-51 
495-66 
497-44 
508-25 
512-18 
512-64 
512-31 
511-17 
510-60 
509-00 
503-19 
501-43 
503-77 
512-41 
515-16 
516-06 
513-70 
509-29 
November | 
513-69 
513-08 
508-73 
508-45 
51006 
513-66 
514-04 
514-41 
512-09 
512-10 
December 
518-08 
518-14 
514-01 
513-52 
513-64 
514-38 
516-53 
514-82 
514-48 
512-97 
Table X. is intended chiefly as a key for comparing the tabular observations. The cross lines indicate 
breaks in the series from new adjustments, which will be found alluded to after Table VIII. 
MAG. AND MET. OBS. 1843. 
