Diurnal Variations for the Magnetic Dip. 



Ixi 



into dip, reductions which have not been performed, the laws for the dip however are quite the same as those 

 for the horizontal component, to which we refer. See also No. 141. 



Diurnal Variation of the Magnetic Dip. — The following Table is deduced from Tables 31 and 48. 



Table 57. — Diurnal Variations of Magnetic Dip for each Month, as deduced from the Eegular Daily 

 Observations made during the Four Years 1843 to 1846. 



Mak. 



























Mean 

 Time. 



Jan. 



Feb. 



March. 



April. 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



b. m. 



12 12 



0-658 ' 



0-294 



0-214 



1-061 



1-743 



1332 



1-509 



0-964 



0-755 



0-407 



0-466 



0-878 



13 12 



0-724 



0-449 



0-773 



1-131 



1-782 



1-506 



1-670 



1-278 



0-592 



0-352 



0-426 



0-744 



14 12 



1-096 



0-578 



0-861 



1-767 



1-899 



1-647 



1-804 



1-433 



0-930 



0-371 



0-462 



0-708 



15 12 



0-452 



0-525 



0-478 



1-404 



1-989 



1-774 



1-914 



1-470 



0-743 



0-070 



0-277 



0-588 



16 12 



0-214 



0-409 



0-567 



1-303 



2-170 



1-918 



2-129 



1-550 



0-750 



0000 



0-156 



0-298 



17 12 



0000 



0-127 



0-538 



1-113 



2-200 



2-120 



2-320 



1-908 



0-635 



0-157 



0-099 



0-104 



18 12 



0-032 



0-040 



0-317 



1-282 



2-373 



2-515 



2-518 



2131 



0-986 



0-440 



0-000 



0-000 



19 12 



0-080 



0-030 



0-696 



1-631 



2-840 



2-883 



2-925 



2-776 



1-756 



0-789 



0-234 



0-152 



20 12 



0-366 



0-164 



1-344 



2-479 



3-455 



3-413 



3-485 



3-548 



2-312 



1-557 



0-669 



0-373 



21 12 



0-534 



0-610 



1-759 



3-133 



3-744 



3-706 



3-963 



3-880 



2-884 



2-200 



1-273 



0-687 



22 12 



0-836 



0-720 



2-060 



3-264 



3-817 



3-655 



4-042 



3-699 



2-924 



2-388 



1-457 



0-983 



23 12 



0-767 



0-689 



1-824 



.3-112 



3-353 



3-039 



3-459 



3-040 



2-348 



2-092 



1-369 



1-008 



12 



0-662 



0.473 



1-369 



2-430 



2-633 



2-230 



2-676 



2-311 



1-610 



1-653 



0-937 



0-929 



1 12 



0-302 



0-217 



0-693 



1-640 



1-762 



1-554 



2022 



1-371 



0-829 



0-920 



0-693 



0-713 



2 12 



0-239 



0-000 



0-336 



1-052 



1-260 



0-974 



1-197 



1-041 



0-467 



0-710 



0-527 



0-558 



3 12 



0-278 



0-009 



0-070 



0-632 



0-935 



0-689 



0-599 



0-544 



0-210 



0-399 



0-496 



0-539 



4 12 



0-227 



0-159 



0-000 



0-368 



0-189 



0-472 



0-372 



0-409 



0-000 



0-445 



0-652 



0-477 



5 12 



0-312 



0-242 



0-134 



0007 



0-000 



0-191 



0-114 



0-000 



0-133 



0-387 



0-208 



0-512 



6 12 



i 0-444 



0-238 



0.292 



0-000 



0-107 



0-000 



0-000 



0-126 



0168 



0-274 



0-303 



0-283 



7 12 



0-505 



0-129 



0-135 



0-410 



0-138 



0-008 



0-296 



0-206 



0-156 



0-339 



0-504 



0-493 



8 12 



0-379 



0-128 



0-144 



0-601 



0-739 



0-372 



0-630 



0-450 



0-491 



0-296 



0-440 



0-735 



9 12 



' 0-439 



0-193 



0-221 



0-807 



1-251 



0-698 



1-051 



0-676 



0-399 



0-304 



0-608 



0-837 



10 12 



0-514 



0-564 



0-249 



0-614 



1-447 



0-850 



1-303 



0-675 



0-518 



0-331 



0-512 



0-857 



11 12 



0-493 



0-407 



0-034 



0-825 



1-693 



1-184 



1-357 



0-850 



0-446 



0-418 



0-566 



0-766 



128. The following are the approximate epochs of maxima and minima in apparent time as deduced from 

 Table 57, distinguishing the epoch of the principal maximum by -f and of the principal minimum by — , 



Jan. 



Feb. 



March. April. May. June. July. Aug. 



Sept. 



Oct. 



Nov. 



Dec. 





h. m. 



h. m. 



h. m. 



h. m. 



h. m. 



h. in. 



h. m. 



h. m. 



h. m. 



h. m. 



h. m. 



h. m. 



-Max. 



22 20 



+ 22 5 



+ 22 5 



+ 22 12 



22 5 



21 30 



21 45 



21 20 



+ 21 55 



+ 22 15 



+ 22 40 



+ 22 55 



Min. 



3 10 



- 2 30 



- 3 50 



- 5 45 



5 45 



6 40 



5 55 



5 25 



- 4 35 



8 15 



5 55 



5 55 



Max. 



+ 14 



12 45 



14 



14 30 





... 



... 



... 



14 35 



12 25 



10 30 



11 15 



Min. 



-17 40 



-18 40 



17 50 



17 



.. . 









17 5 



-16 25 



-18 15 



-18 15 



These epochs are very nearly the same as those obtained for the horizontal component No. 69. The 



diurnal variation of magnetic dip at Makerstoun has only one maximum and minimum in the four months 



May to August, and it has two maxima and two minima in the remaining eight months. The morning 



minimum near 6^ a.m., is the principal minimum in the four months October to January, in February the two 



minima are equal ; in the other months the principal or only minimum, occurs near 6*" p.m. ; the principal 



maximmn of dip occurs in each month with the exception of January near 10** a.m. It is only in the four 



I winter months November to February that the 2** a.m. maximum is well marked. The variations of the epochs 



' of maxima and minima will be found with most accuracy from Table 58, which contains the diurnal variations 



I for groups of months. 



