248 Abstracts of the Makerstoun Observations, 1843. 1 
force (the secular changes being eliminated), the following quantities have been obtained, which shew the varia- 
tions of the magnetic dip for the different months of the year : — 
JaD. Feb. March. April. May. June. July- Aug. Sept. Oct. Nov. Dec. 
0'-145 0'-374 0'-605 C-518 0'-000 0'-106 0'-470 0'-636 0'-377 C-578 O'-360 0'-269 
These quantities indicate maxima of magnetic clip about the periods of the equinoxes, and minima about the 
periods of the solstices. 
TABLE XXII.— Diurnal Variations of Magnetic Dip, deduced from Tables XI. and XVIII. 
Period. 
18\ 
20*. 
23 h . 
0b. 
2 h . 
4*. 
6". 
8*. 
10*. 
Range. 
January 
0-158 
i 
0-235 
0-714 
/ 
1 
0-697 
0-208 
/ 
0-000 
, 
0-321 
0-460 
0-406 
0 
714 
February 
0-331 
0-043 
0-618 
0-468 
0-129 
0-000 
0-368 
0-290 
0-328 
0 
618 
March 
0-503 
0-633 
1-262 
1-238 
0-386 
0-000 
0-114 
0-403 
0-380 
1 
262 
April 
0-900 
1-086 
2-116 
1-922 
0-801 
0176 
0-000 
0-519 
0-870 
2 
116 
May 
1-505 
1-980 
2-598 
2-187 
0-880 
0-526 
0-000 
0-074 
0-973 
2 
598 
June 
1-451 
2-026 
2-789 
2-317 
1-181 
0-636 
0-391 
0-000 
0-443 
2 
789 
July 
1-640 
1-949 
2-932 
2-655 
1-532 
0-248 
0 000 
0-250 
0-824 
2 
932 
August 
1-414 
1-947 
2-683 
2073 
0-789 
0-154 
0 000 
0-182 
0-202 
2 
683 
September 
0-486 
1-188 
2-109 
1-508 
0-651 
0-000 
0-358 
0-127 
0-124 
2 
109 
October 
0-248 
0-712 
1-704 
1-507 
0-418 
0-102 
0-045 
0-000 
0-048 
1 
704 
November 
0-073 
0-195 
0-759 
0-811 
0-627 
0-153 
0-091 
0-000 
0-263 
0-367 
0 
759 
December 
0-000 
0011 
0-507 
0-556 
0-577 
0-556 
0-394 
0-594 
0-672 
0-740 
0 
740 
Spring 
0-520 
0-528 
1-274 
1-150 
0-379 
0-000 
0-103 
0-345 
0-467 
1 
274 
Summer 
1-424 
1-876 
2-664 
2-277 
1-089 
0-361 
0-021 
0-000 
0-637 
2 
664 
Autumn 
0-630 
1-197 
2-080 
1-611 
0-534 
0-000 
0-049 
0-018 
0-040 
2 
080 
Winter 
0-000 
0-070 
0-583 
0-557 
0-228 
0-085 
0-228 
0-388 
0-427 
0 
583 
Winter Solstice 
0-019 
0-000 
0-528 
0-471 
0-140 
0-000 
0-200 
0-300 
0-339 
0 
528 
Equinoxes 
0-465 
0-835 
4-728 
1-474 
0-494 
0-000 
0-060 
0-193 
0-286 
1 
728 
Summer Solstice 
1-405 
1-878 
2-653 
2-210 
0-998 
0-293 
0-000 
0-029 
0-513 
2 
653 
The Year 
0-543 
0-818 
1-550 
1-298 
0-457 
0-011 
0-000 
0-087 
0-293 
1 
550 
Diurnal Variations of Magnetic Dip. 
Spring in the foregoing table consists of the months of February, March, and April. The means for the 
quarters may be taken as types of the months from which they are obtained. 
I n winter the diurnal curve is double ; it is probably double also in spring ; these means only shew portions 
of a single curve in summer and autumn. 
In the mean for the year, — 
The maximum of dip occurs about 9 h 30 m a.m., Makerstoun mean time. 
The minimum 5 h 0 m P.M., 
In the mean for winter, — 
The maximum occurs about 10 h 10 m a.m., Makerstoun mean tinu 
The minimum occurs before 5 h a.m., 
A secondary minimum occurs about 3 h 10 m p.m., 
A secondary maximum occurs after 9 h p.m., 
Nearly the same periods occur for spring, the minimum at 3 h 10'" p.m. being the principal minimum ; the 
minimum occurs as late as 6 h p.m. in summer. 
In order, if possible, to obtain the periods of maxima or minima not shewn in the 9 daily observations, 
the following table has been formed. 
