248 



Abstracts of the Makerstoun Observations, 1843. 



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 : — 



Jan. Feb. March. April. May. June. July- ■^'^S- Sept. Oct. Nov. Dec. 



0'-146 0'-374 O'-605 0'-518 O'-OOO 0'-106 0'-470 0'-636 0'-377 0'-578 0'-360 0'-269 



These quantities indicate maxima of magnetic dip 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. 



181'. 



20''. 



221-. 



23''. 



0>>. 



2h_ 



■li\ 



e''. 



8i>. 



lox. 



Range. 



Januar}^ 



0-158 



/ 

 0-235 



/ 



0-714 



/ 



0-697 



0-208 



/ 

 0-000 



0-321 



0-460 



0-406 



1 

 0-714 



February 



0-331 



0-043 



0-618 









468 







129 



0-000 



0-368 



0-290 



0-328 



0-618 



March 



0-503 



0-633 



1-262 





1 



238 







386 



0-000 



0-114 



0-403 



0-380 



1-262 



April 



0-900 



1-086 



2-116 





1 



922 







801 



0176 



0-000 



0-519 



0-870 



2-116 



May 



1-505 



1-980 



2-598 





2 



187 







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 



0000 



0-250 



0-824 



2-932 



August 



1-414 



1-947 



2-683 





2 



073 







789 



0-154 



0000 



0-182 



0-202 



2-683 



September 



0-486 



1-188 



2-109 





1 



508 







651 



0-000 



0-358 



0-127 



0-124 



2-109 



October 



0-248 



0-712 



1-704 





1 



507 







418 



0-102 



0-045 



0000 



0-048 



1-704 



November 



0-073 



0-195 



0-759 



0-811 







627 







153 



0-091 



0-000 



0-263 



0-367 



0-759 



December 



0-000 



0-011 



0-507 



0-556 







577 







556 



0-394 



0-594 



0-672 



0-740 



0-740 



Spring 



0-520 



0-528 



1-274 





1 



150 







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 







534 



0-000 



0-049 



0-018 



0-040 



2-080 



Winter 



0000 



0-070 



0-583 









557 







228 



0-085 



0-228 



0-388 



0-427 



0-583 



Winter Solstice 



0-019 



0-000 



0-528 









471 







140 



0-000 



0-200 



0-300 



0-339 



0-528 



Equinoxes 



0-465 



0-835 



1-728 





1 



474 







494 



0-000 



0-060 



0-193 



0-286 



1-728 



Summer Solstice 



1-405 



1-878 



2-653 





2 



210 







998 



0-293 



b-000 



0-029 



0-513 



2-653 



The Year 



0-543 



0-818 



1-550 





1 



298 







457 



0-011 



0-000 



0-087 



0-293 



1-550 



Diurnal Variations of Magnetic Dip. 



Spring in the foi'egoing 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. 



In 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*^ 30™ a.m., Makerstoun mean time. 

 The minimum 5'^ 0™ p.m., 



In the mean for winter, — 



The maximum occurs about 10*^ 10™ a.m., Makerstoun mean time. 



The minimum occurs before 5*^ a.m., • ••- 



A secondary minimum occurs about ^ 10™ p.m., 



A secondary maximum occurs after 9"^ p.m., 



Nearly the same periods occur for spring, the minimum at 3'' 10™ p.m. being the principal minimum ; the 

 minimum occurs as late as 6'^ p.m. in summer. 



In order, if possible, to obtain the periods of maxima or minima not shewn in t|ie 9 daily observations, 

 tlie following table has been formed. 



f 



