XXVill GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. 
lst, The average westerly excursion from the mean position for the hour is greatest in the winter and 
spring quarters about 1" or 2) p.mw.; and about 8" a.m, in the summer and autumn quarters, although the 
values vary little in the summer quarter from 4" a.m. to 1 p.m,, and in the autumn quarter a secondary 
maximum occurs at 3" p.m. 
2d, The average easterly excursion is least about 8 a.m. in each quarter, with the exception of summer, 
in which it is equally small at 5 p.a.: the average easterly excursion from the hourly mean of ail the obser- 
vations (Table 18) has the minimum decidedly marked at 6% p.m. 
3d, The minimum westerly excursion oceurs about 95 p.m. in all the quarters. 
4th, The maximum easterly excursion occurs earliest in winter, about 6" p.m., and latest in summer, 
namely after midnight; while in the equinoctial quarters it occurs betwixt these epochs, the values varying 
little from 65 p.m. till midnight. 
5th, The mean excursion, without reference to direction, has its greatest value earliest in winter, about 
6" p.m. ; about 9 and 10" p.m, in the equinoctial quarters; and in summer there are two maxima of nearly 
equal value, immediately after midnight and at 115 a.m., with a secondary minimum about 6" a.m. 
6th, The mean excursion has its least value about 5® to 6" 4 m. in winter and spring; a secondary mini- 
mum, as noted above, occurs about the same hour in summer, and 4" in autumn; but the actual minimum 
occurs, distinctly marked, between 6" and 10 p.m. in summer, and, less distinctly marked, about 5® p.m. in 
autumn. 
45. It appears from these results, that the diurnal law of mean disturbance is not constant throughout the 
year, as has been supposed; in fact the law for summer is nearly the reverse of that for winter, while that for 
autumn is nearly intermediate between the two, a secondary maximum occurring in the latter at 9° a.m. In 
the winter and spring quarters there is a tendency to a secondary minimum about 4» or 5® p.m. 
TABLE 19.—Mean Disturbances of Magnetic Declination, or Differences from the Monthly Means, at 
the corresponding Hours in 1844 and 1845, as deduced from the selected series in each Year. 
Mean Westerly Disturbance. Mean Easterly Disturbance. | Mean Disturbances. 
Nov. | Feb. | May. =| Nov. | Feb. | May. g. H Feb. | May. | Aug. 
Dee. | Mar. | June. 4 . | Dec. | Mar. i al . | Mar. | June. | Sept. 
| Jan. | April.| July. : Jan. | April. A April.| July. | Oct. 
’ , 
1:47] 1-02) 1-56) 1-2 2.26 | 
1-47} 1-17] 1- . 2-45 
1-56| 1-09} 1. : 1-84 
1-43| 1-50] 2. . 1.92 
1-77| 1-92] 1. ; 1-38 
1:56| 1-82] 2. é 
1-39] 1-74 
1:55] 1-72 
1-83 
1-83 
2-22| 1-66 
1-63 
1-52 
1-47 
1-55 
1-46 
1-46 
1-41 
1-48 
1-65 
1-64 
1-71 
1-54 
1-62 
1:50 
1-49 
1:34 
1-04 
0-98 
1-12 
1-17 
1-06 
1-03 
1-33 
ao ae 
f2demweats 
BOODANIDON BWW 
I. 
]- 
1- 
lah 
1 
| 1 
1 
| 2 
| 2. 
2. 
1- 
]- 
1.07 | 
i4| 1-05 || 0-86 
Se SmonedhYheykaadwsnwtwbaanen 
WRONUTIUDAWSOUNOHIDBRABDRGAANE 
46, Diurnal Variation of the probable error of an Observation of Magnetic Declination.—It appears from 
the previous conclusions, that the best hour to make an observation of magnetic declination in winter and 
spring, is about 6" a.s.; in the summer quarter, from 5" p.m. to 10" p.m.; and in autumn from 4" to 5" p.m. 
