1 



Geneeal Results of the Makerstoun Observations. 



In the mean of both years, each month, with the exception of November and December, has more observations 

 greater than the monthly mean than it has less, the excess being from 5 to 13 in 100 ; in November the num- 

 bers of positive and negative departures are equal, and in December the greatest difference occurs between the 

 positive and negative departures, the latter being greater than the former by 16 in 100. 



Monthly Variations for the Vertical Component. 



Table 45. — Mean Variations of the Vertical Component of Magnetic Force free from Regular 

 Secular Change, with reference to the Moon's Age and Declination. 















After 













Moon's 

 Age. 



1843. 



1844. 



1845. 



1846. 



Mean. 



Moon 

 farthest 



1843. 



1844. 



1845. 



1846. 



Mean. 













North. 











0-00 



d. d. 



0-00 



0-00 



0-00 



0-00 



0-00 



d. d. 



0-00 



0-00 



0-00 



0-00 



14—16 



-0016 



-0062 



-0010 



+ 0020 



-0017 



27— 1 



+ 0053 



+ 0038 



-0005 



-0005 



+ 0020 



17—20 



+ 0012 



-0002 



+ 0012 



+ 0066 



+ 0022 



2— 5 



+ 0044 



-0008 



-0064 



+ 0010 



-0004 



21—24 



+ 0013 



+ 0044 



+ 0005 



+ 0046 



+ 0027 



6— 8 



+ 0008 



-0004 



+ 0006 



-0047 



-0009 



25—28 



+ 0031 



+ 0013 



-0027 



-0031 



- 0003 



9 — 12 



-0018 



-0026 



+ 0001 



+ 0003 



-0010 



29— 1 



-0027 



+ 0008 



-0022 



-0004 



-0011 



13—15 



+ 0020 



+ 0012 



+ 0011 



+ 0005 



+ 0012 



2— 5 



-0010 



+ 0010 



+ 0052 



-0057 



-0001 



16—19 



-0036 



+ 0004 



+ 0050 



-0048 



-0007 



6— 9 



+ 0027 



+ 0031 



+ 0006 



-0023 



+ 0010 



20—22 



-0048 



-0015 



+ 0025 



+ 0034 



,-0001 



10—13 



-0028 



-0042 



-0019 



-0016 



-0026 



23—26 



-0028 



0000 



-0023 



+ 0048 



-0001 



Variations of the Daily Mean Vertical Component, with reference to the Moon's Age and Declination. — 

 Table 45 has been formed from the Tables in pi'evious volumes, and in this volume, pages 18 and 35 ; the 

 means for 3 or 4 days are given, positive when greater than the mean for the year, and negative when less. 



96. The conclusions from the means of 4 years in Table 45, are, — 



Ls;", That the vertical component is a maximum at the quadratures, and a minimum at conjunction and 

 at opposition ; the principal maximum occurs about 7 days after opposition, and the secondary maximum about 

 7 days after conjunction ; the difference of the values of the two maxima is due chiefly to the year 1846, 

 the only year which does not exhibit two maxima and two minima. 



2d, That the vertical component is a maximum when the moon is farthest north, and also when it is 

 farthest south, and between these epochs it is a minimum ; the minima occurring when the moon is rather 

 south of the equator. This result is shewn, though with some irregulai'ity, in the numbers for each year. It 

 should be remembered, in glancing over these Tables, that the number which indicates a maximum may have 

 the negative sign, and that which indicates a minimum may have the positive sig-a ; thus, in 1845 the prin- 

 cipal maximum occui's about 4 days after the moon's greatest south declination, the secondary maximum occurs 

 when the moon is farthest north, and the minima occur when the moon is about 3 days north of the equator. 



Variation of the Diurnal Range of the Vertical Component, with reference to the Moon's Age and Declina- 

 tion. — The means of groups of days given in Table 46, have been deduced from the Tables in former volumes, 

 and in this volume, pages 19 and 36. 



Table 46. — Diurnal Range of the Vertical Component of Magnetic Force, with reference to the 









Moon's 



Age and Declination. 























After 













Moons 

 Age. 



1843. 



1844. 



1845. 



1846. 



Mean. 



Moon 



farthest 



North. 



1843. 



1844. 



1845. 



1846. 



Mean. 



d. d. 



0-00 



0-00 



0-00 



0-00 



0-00 



d. d. 



0-00 



0-00 



0-00 



0-00 



0-00 



14—16 



0423 



1238 



0617 



0943 



0805 



27— 1 



0535 



0578 



0587 



0829 



0632 



17—20 



0406 



1149 



0737 



1141 



0858 



2— 5 



0596 



0930 



0976 



0637 



0785 



21—24 



0316 



0544 



0700 



0870 



0607 



6— 8 



0465 



0850 



0776 



0738 



0707 



25—28 



0502 



0446 



0658 



0568 



0543 



9—12 



0384 



0657 



0681 



1113 



0709 



29— 1 



0374 



0540 



0610 



0731 



0564 



13—15 



0503 



0626 



0482 



0637 



1 0562 



2— 5 



0395 



0463 



0627 



0640 



0531 



16—19 



0382 



0773 



0767 



0518 



1 0610 



6— 9 



0678 



0688 



0710 



0875 



0738 



20—22 



0349 



0872 



0475 



1068 



0691 



10—13 



0505 



1221 



0618 



0761 



0776 



23—26 



0426 



0946 



0478 



0952 



0700 



