Horizontal Component of Magnetic Foece. 



355 



of June and July as the most perfect representative of the diurnal curve at Makerstoun for the sun north of 

 the equator, and compare this curve with that similarly obtained for the months of December and January 

 when the sun is farthest south, we obtain the following variations corresponding to the differences of the hourly 

 means for the two curves : — 



12 h l h a.m. 2 h 3 h 4 h 5h 6 h 7 h 8 h 9 h 10h llh 1 ' l h P.M. 2 h 3h 4 h 5 h 6 h 7 h 8 h 9 h 10 h ll h 

 3'-43 4'-12 4'-22 5'-00 5'-69 7'-12 7'-89 7'-77 6'-85 5'-56 4'-47 2'-29 l'*32 0'-40 O'-OO O'-ie 1''44 2'-09 2'-39 2'-21 2'-09 2'-39 2'-54 3'-09 



It follows, therefore, that by the addition of the above quantities, representing the motion of the magnetic 

 needle for the southern hemisphere, which has its maximum of westerly declination about 6 h a.m., and its mini- 

 mum about 2 n p.m., to the quantities representing the diurnal motion for midsummer at Makerstoun, we obtain 

 variations which represent the midwinter motion for the same place. The same result is obtained in the com- 

 parison of the midsummer curve with that for November and February, and even for October and March, 

 though with less accuracy as regards the epoch of minimum for the differences. 



It will be interesting to determine, from other observations, the latitude for which the midwinter curve 

 ceases to have the characteristic of a northern curve. 



Horizontal Component of Magnetic Force. 



TABLE XXII. — Mean Values of the Variations of the Horizontal Component of Magnetic Force, the 

 whole Horizontal Component being Unity, for each Civil Week-Day, Week, and Month of 1844. 



Civil. 

 Day. 



Jan. 



Feb. 



March. 



April. 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 





0-00 



0-00 



0-00 



0-00 



0-00 



0-00 



0-00 



0-00 



0-00 



o-oo 



0-00 



0-00 



1 



2499 



3002 



2850 



1933 



2842 



4579 



4224 



5142 



[4110] 



2943 



5002 



[5257] 



2 



2187 



2264 



2849 



2170 



3437 



[4291] 



4635 



3391 



3931 



4172 



4607 



5429 



3 



2719 



2374 



[2395] 



2338 



3104 



4175 



4732 



3608 



4109 



4147 



[4791] 



5338 



4 



2969 



[2347] 



2428 



2237 



2842 



4392 



4668 



[4095] 



4424 



4299 



4635 



5400 



5 



2755 



2080 



1970 



3195 



[3326] 



4280 



4430 



4228 



4322 



4319 



4749 



5097 



6 



2376 



2134 



1700 



2533 



3798 



4355 



4313 



4095 



4246 



[4411] 



4983 



5228 



7 



[2519] 



2227 



2083 



[2904] 



3431 



4336 



[4495] 



4109 



4974 



4627 



4903 



5404 



8 



2474 



2401 



1898 



2780 



3345 



4018 



5209 



4603 



[4547] 



4292 



4976 



[5439] 



9 



2171 



2671 



2493 



3237 



3170 



[4301] 



4054 



5267 



4438 



4782 



5114 



5624 



10 



2363 



2559 



[2401] 



3443 



3550 



4446 



4298 



3920 



4511 



4840 



[4822] 



5548 



11 



2485 



[2767] 



2521 



3151 



3412 



4140 



4494 



[4505] 



4792 



4900 



4816 



5734 



12 



2454 



2743 



2471 



3367 



[3515] 



4511 



4778 



4267 



4663 



4742 



4431 



5708 



13 



2709 



3004 



2936 



3363 



3682 



4890 



4882 



4362 



4792 



[4871] 



4687 



5575 



14 



[2692] 



3224 



3200 



[3277] 



3660 



4430 



[4748] 



4613 



4809 



5106 



4970 



5268 



15 



2748 



3172 



3210 



3321 



3615 



4371 



5064 



4585 



[4595] 



4761 



5239 



[5305] 



16 



2853 



2856 



3004 



3063 



3580 



[4479] 



4649 



4630 



4553 



4872 



4619 



4714 



17 



2905 



3496 



[3065] 



3396 



3490 



4388 



4619 



4572 



4319 



4676 



[4612] 



5078 



18 



2849 



[3183] 



3077 



2549 



4012 



4533 



4224 



[4696] 



4434 



5016 



4309 



5484 



19 



2803 



3212 



2797 



2733 



[3998] 



4260 



4297 



4634 



4602 



5187 



3970 



4963 



20 



2660 



3228 



3097 



2730 



4417 



4502 



4749 



4910 



4383 



[4234] 



4564 



4868 



21 



[2866] 



3135 



3121 



[3167] 



4494 



4539 



[4487] 



4847 



3826 



2514 



4637 



4589 



22 



2761 



3013 



3164 



3510 



3998 



4222 



4603 



4795 



[4367] 



4026 



4050 



[5064] 



23 



3265 



3028 



3108 



3752 



3419 



[4333] 



4600 



4591 



4386 



3979 



3437 



5201 



24 



2859 



3476 



[3263] 



3727 



3885 



4176 



4446 



3919 



4743 



4252 



[4551] 



5358 



25 



2660 



[3129] 



3304 



3650 



3990 



4119 



4949 



[4362] 



4257 



3573 



4780 



5405 



26 



2733 



3294 



3412 



2614 



[3858] 



4441 



4252 



4438 



3861 



3536 



5008 



5453 



27 



2764 



3140 



3473 



2488 



3919 



4403 



4648 



4095 



3609 



[4052] 



5394 



5562 



28 



[2672] 



2822 



3090 



[2951] 



4017 



5097 



[4634] 



4337 



4011 



3997 



5068 



5055 



29 



2465 



2580 



2030 



3161 



3920 



5025 



4312 



4586 



[3763] 



4357 



5138 



[4829] 



30 



\ 2825 





-0091 



2953 



3906 



[4686] 



4407 



3921 



3984 



4598 



5173 



3923 



31 



| 2583 





[1911] 





4414 





5233 



3692 





4777 





4502 



Mean 



I 2663 



I 



2845 



2661 



2976 



3679 



4425 



4584 



4376 



4360 



4344 



4740 



5212 



