242 ABSTRACTS OF THE MAKERSTOUN OBSERVATIONS, 18438. 
VARIATIONS OF THE VERTICAL COMPONENT OF MAGNETIC FORCE, WITH REFERENCE TO THE 
Moon’s DECLINATION. 
The second portion of Table XVI., in groups, gives the following means :— 
af days to : aay, Moon farthest North, 0:000107 13 et to 15 Haka Moon farthest South, 0:000077 
Berane 0:000099 16. 19 0:000027 
: dsocbe 3 ne 0:000066 20e eice 22 ee 0:000016 
d) cote UP Bo 0:000043 DB i insets PRN ae 0:000034 
These means indicate a well marked minimum at the passage of the equator northwards ; a well marked 
maximum at the period of greatest north declination; a diminution of the component from thence till after the 
passage of the equator southwards ; and a secondary maximum at the greatest south declination. Though the 
latter is not well shewn in these groups, the means on the whole shew, maxima of the vertical component at the 
periods of greatest north and south declination, and minima when the declination is zero. 
VARIATIONS OF THE VERTICAL CoMPONENT OF MAGNETIC FORCE, WITH REFERENCE TO THE Moon’s 
DISTANCE FROM THE EARTH. 
Means of Groups. 
6 days after Apogee to 6 days before Perigee, 0:000116 | 6 days after Perigee to 6 days before Apogee, 0:000060 
5 days to 2 days before Perigee, . .  0:000110 | 5 days to 2 days before Apogee, - «  0:000054 
1 day before to 1 day after Perigee, . 0:000084 | 1 day before to 1 day after Apogee, . 0°000036 
2 days to 5 days after Perigee, . .  0°000098 | 2 days to 5 days after Apogee, -  .  0:000084 
TABLE XVII.—Means of the Balance Magnetometer Readings corrected for Temperature at the 
Observation Hours for each Month in 1848. 
Month. . 20%, 2h, 0h, 2h, 4b, 6h, 8h, | 10%, 
Mic. Div. Mie. Div. Mic. Div. Mic. Div. Mie. Diy. Mic. Div. Mic. Diy. Mic. Div. Mic. Div. 
January 756-0 762-6 . 768-3 769-2 767-7 774-4 777-0 
February 740-0 745-5 ; 744-2 745-4 753-2 761-9 763-9 
March 707-5 713-8 “g 708-6 707-1 715-8 730-0 735-5 
April 662-2 668-9 ; 669-7 670-4 688-3 721-6 709-2 
May 659-8 667-0 . 650-5 649-4 665-2 674:7 679-6 
June 662-2 671-4 : 655-6 651-4 664-6 677-3 675-8 
July 638-9 647-6 “ 643-7 648-6 659-4 664-5 667-8 
628-2 638-5 624-8 634-5 643-6 656-4 653-3 
euEuE {| 2 803-4 790-2 | 790-5 | 799-7 | 807-6 | 806-0 
September 805-9 823-5 . 817-8 824-4 831-5 836-0 824.7 
October 801-1 812-0 21- 819-4 | 821-5 830-9 829-9 821-3 
f 804-2 808-4 ‘ : 821-2 827-0 829.5 821-3 818-9 
November ; : 
841-1 843-1 , : 841-3 849-3 856-9 856-0 859-3 
December 824-2 826-1 D : 833.4 839-9 848-1 849-1 853-4 
Table XVII. is intended chiefly as a key for comparing the tabular observations. The cross lines in the 
Table indicate that a break has occurred in the series; the means so separated are not comparable with each 
other. The periods at which the needle was removed have been already mentioned.—See remarks to Table 
XV, 
