SOLAR-DIURNAL YARIATION OF THE DIP AND TOTAL FORCE. 



To make the combination of the horizontal and vertical force components com- 

 plete, there remains the discussion of the regular solar-diurnal variation and its 

 annual inequality, of the resulting dip and total force. 



Table III, of Part V, contains the solar-diurnal variation, expressed in parts of the 

 force, of the horizontal component, freed from the larger disturbances ; Table III, 

 of Part VIII, contains similar information with regard to the vertical component. 

 The numbers of these tables, however, cannot be combined directly, owing to the 

 eleven year inequality which requires that the two sets of components should cover 

 precisely the same interval of time. In the present case the table of the horizontal 

 force extends from July, 1840, to July, 1845, a five year series; whereas the table 

 of the vertical force extends over four years only ; a new table of monthly normals 

 of the horizontal component was therefore prepared, in which the first year's obser- 

 vations were omitted. This was done by the same method as had been followed in 

 the preparation of the former annual values of Part V. The following table differs 

 from that of Table I, of Part V, only in the number of observations employed, and 

 extends from July, 1841, to July, 1845. 



Table I. — Recapitulation of the Houkly Normals op the Horizontal Force (expressed in f 

 Scale Divisions) for each Month op the Year, and for Summer, Winter, and the whole | 

 Tear, between July, 1841, and July, 1845. | 



1841-45 



0" 



1 



2 



3 



4 



5 



6 7 



8 



9 



10 



lin 



-t-21J- 



July 



August 



September 



October . 



November 



December 



January . 



February . 



Marcli 



April 



May 



Juue 



791 

 813 

 829 

 850 

 853 

 883 

 905 

 915 

 919 

 945 

 947 

 972 



790 

 813 

 827 

 846 

 852 

 879 

 902 

 914 

 917 

 944 

 946 

 972 



789 

 813 

 830 

 847 

 850 

 878 

 902 

 913 

 915 

 944 

 944 

 972 



788 

 812 

 829 

 845 

 849 

 877 

 901 

 912 

 915 

 942 

 942 

 972 



787 

 811 

 826 

 844 

 848 

 874 

 899 

 910 

 915 

 940 

 942 

 96S 



786 

 809 

 824 

 844 

 846 

 873 

 899 

 908 

 913 

 938 

 940 

 966 



785 

 808 

 821 

 844 

 845 

 871 

 899 

 906 

 912 

 938 

 938 

 962 



788 

 815 

 830 

 848 

 849 

 872 

 898 

 908 

 915 

 940 

 944 

 968 



796 

 825 

 842 

 854 

 853 

 874 

 900 

 910 

 920 

 948 

 954 

 973 



803 

 835 

 850 

 860 

 859 

 878 

 908 

 914 

 927 

 958 

 961 

 980 



806 

 837 

 853 

 865 

 862 

 885 

 914 

 920 

 931 

 965 

 960 

 983 



804 

 830 

 852 

 864 

 865 

 892 

 918 

 922 

 936 

 966 

 956 

 980 





Year 



Summer . 

 Winter . 



885.2 

 882.8 

 887.5 



883.5 

 882.0 

 885.0 



883.1 

 882.0 

 884.2 



882.0 

 880.8 

 883.2 



880.4 878.8 

 879.2 877.2 

 881.7 880.5 



877.4 

 875.3 

 879.5 



881.2 

 880.8 

 881.7 



887.4 

 889.7 

 885.2 



894.4 

 897.8 

 891.0 



898.4 

 900.7 

 896.2 



898.8 

 898.0 

 899.5 



( 15 ) 



