364 



Results of Makeestoun Observations, 1844. 



TABLE XXXI. — Mean Variations of the Horizontal Component of Magnetic Force, with reference 

 to the Moon's Hour- Angle for each Lunation, for the Six Summer and Six Winter Lunations, 

 and for the Twelve Lunations of 1844. 



Table XXXI. has been formed in the same manner as Table XI. The numbers in the first column are 

 Sfths of the moon's hour-angles from the meridian. 



Diurnal Variation of the Horizontal Component with reference to the Moon's Hour-Angle. — In this case, 

 as in that for the magnetic declination, the means for the lunations in winter give a somewhat different law 

 from those for the lunations in summer. The following are the means at nearly two-hourly intervals for the 

 .•summer and whiter groui)S, and for the whole twelve lunations : — 



IS' 50" ly 45" W 40» 211' 35"' 

 131 215 197 104 

 156 073 000 070 



070 070 025 012 



In the winter group, for which the moon is in opposition north of the equator — 



The maximum occurs about 2 hours after the moon's inferior transit. 

 The minimum 2 hours superior transit. 



If there are secondary maxima or minima, they are not well marked in the means for 1844. 

 In the summer group, for which the moon is in opposition south of the equator, the variation is distinctly 

 double ; 



The principal maximum occurs about 2 hours after the moon's inferior transit. 



The principal minimum 4^ before superior transit. 



A secondary maxiuium 2 after 



A secondary niinimum 8 after 



