EXTREME POSITIONS. 257 
TABLE XXXI.—Means of the Quantities in the three preceding Tables for periods of Three Months, 
and for the Year 1843, with the Mean Positive and Negative Excesses of the Excursions of the 
Magnets. 
West Declination. Bifilar Magnetometer. Balance Magnetometer. Ranges. 
Period. | 
Above | Below Declina-|_ Hor. Ver. 
Excess. Mean. | Mean. tion. Comp. Comp. 
Observations. 
iv. | Se. Div. || Mic. Div. Mic. Div. X=1 Y=.1 
Spring 2. 21-67 |— 9-13 “ ‘0 |-11-6|| 253-7 | 68-5 0-00669 | 0-00319 
Summer 5 17-08 |—11-17 o ‘9 |— 1-3 || 126-5 | 117-5 : 0-01057 | 0-00230 
Autumn 11-84 7 . “7 |+ 5:3] 86-1 | 87-7 : 0-00623 | 0.00183 
Winter . 6-69 . : 2-1] 70-7 | 37-0 |+ 0-00329 | 0:00118 
The Year 14-32 5 D . 2-4//134-2 | 77-6 |+ 56: 000669 | 0.00212 
Spring 7:39 : 4:7|| 10-1 | 62-9 0-00376 | 0.00089 
Summer 9-12 j : D 1:5 5:7 | 37-5 . 0-00323 | 0.00048 
Autumn 9-77 , 9-4 98-1 . 0-00356 | 0.00122 
Term-Day. 
Winter 4.43 + 9-1 . 14-5 : 0-00163 | 000028 
The Year . 7-55 : 5 : 3-9 . 53-2 : 0-00304 | 0-00072 
Spring o 13-50 |— 7-19 “ 25-4 |— 1-7 E 52-4 : 0-00529 | 0.00143 
‘Summer 16-22 |—11-13 . 60-9 |—37-2 97-4 0-00728 | 0-00158 
Autumn 7-60 |+ 0-41 : 15-3 |+ 5-9 p 48-8 0-00436 | 0-00089 
Winter 11-00 |- 6-47 . 18-8 |-—11-2 8-5 |4+ 32. 0-00273 | 0.00060 
The Year 12-41 |— 5-88 : 29-5 s 9-3 D D 0-00507 | 0-00121 
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The foregoing Table has been formed from the three preceding it by taking the means of the excesses or 
defects, and ranges, for periods of three months. 
The extremes, given in Tables XXVIII. and XXIX., are evidently imperfect, as the observations include 
only a limited portion of the 24 hours; the conclusions to be drawn from the previous Table must, therefore, 
be very restricted. 
From all the observations, the excursions of the declination-needle towards the east are shewn to exceed 
those towards the west; they all agree also in making this excess greatest in Summer. 
The results of the horizontal component differ in the three kinds of observations ; on the whole, the devia- 
tions from the mean seem to be more negative than positive. 
For the vertical component, it has already been shewn that no result for ranges can be trusted that does 
not include observations between midnight and sunrise. The term-day observations which include the 24 hours 
give the excess negative; and although the number of days from which this result is obtained are few, yet it is 
true for 9 out of the 12 term-days, and for the remaining 3 the positive excess is very trifling. 
MAG. AND MET. oss. 1843. . 3T 
