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. Aug. Sept. Oct. Nov. Dec. 
0°145 0°374 0605 07518 0°000 0°106 0°470 0°636 0°377 0578 0°360 0269 
These quantities indicate mawima 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. 
January 
February 
March 
April 
May 
June 
July 
August 
September 
October 
November 
December 
Spring 
Summer 
Autumn 
Winter 
Winter Solstice 
Equinoxes 
Summer Solstice 
The Year 
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. 
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 «-ossecesseeeceseeees HH OM 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., ste eee cere 
A secondary minimum oceurs about 34 10™ p.m, ---+ 
A secondary maximum occurs after 9 P.M., +++ +++ eer see eee eee eee ees 
Nearly the same periods occur for spring, the minimum at 3" 10™ p.m. being the principal minimum ; the 
minimum occurs as late as 62 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. 
