25 ABSTRACTS OF THE MAKERSTOUN OBSERVATIONS, 1843. 
TABLE XXX.—Differences of the Extreme Readings of the Three Magnetometers from the Monthly 
Means, for the Hours at which the Extreme Readings occurred during the Term-Day Obser- 
tions in 1843, together with the Ranges of the Three Magnetic Elements during each Term-Day. 
Westerly Declination. Bifilar Magnetometer. Balance Magnetometer. Ranges. 
Reading 
greater than 
Mean. 
Reading 
greater than 
Mean. 
Greater than Less than 
Reading less 
Mean, Mean. 
Reading less ||Declina-|Hor. Comp.|Ver. Comp 
than Mean. 
than Mean. tion. | of Force. | of Force. 
1843. h. | Se. Div. . | Mie. Div. \* Mie. Diy. X=1 Y=1. 
Jan. 18, 19 05 : . — 65 + 71 — 15-0 : 0-00194 | 0-00031 
Feb. 24, 25 . : : —41-3 +30-9 — 101-6 : -00501 | -00124 
Mar. 22, 23 : : : + 8-1 86:3 . 00363 | -00114 
Apr. 19, 20 : . . . - 86 ; p 00263 | -00028 
May 26, 27 D . 20- : 7-0 . -00489 | -00096 
June 21, 22 |} --- wae ree: : 0-5 . -00231 | -00031 
July 19, 20 . : : : . . E -00249 | -00017 
Aug. 25, 26 : : : . : . : -00388 | -00063 
Sept. 20, 21 : : . : . : 4 -00396 | -00176 
Oct. 18, 19 3 : . . : : 4 -00283 | -00127 
Nov. 24, 25 . : ol D i . . -00170 | -00032 
Dec. 20, 21 : : . 5 4 : . -00124 | -00021 
When the hours at which the extreme positions occur are between 10" Gott, and 18" Gott., approximate 
means have been taken, in order to deduce the differences between the extreme position and the mean position. 
The differences of the greatest and least readings in the year from the monthly means for the hours at . 
which the extremes occurred, together with the ranges for the year, are as follow :— 
From the Daily Observations. 
West Declination, greatest, Feb. 244 4», + 15/95; least, Feb. 64 104, —36°75; Range of Declination =59’-29. 
Bifilar Magnetometer Reading, greatest, July 252 44, + 96:2 Sc. div.; least, May 64 10, —79:1 Sc. div.; Range of Hor. comp. =0:01839. 
Balance Magnetometer Reading, greatest, April 54 64, +3440 Mic. div.; least, May 64 104, — 257-2 Mic. div.; Range of Ver. comp. =0:00599- 
From the Extra Observations, and from all the Observations. 
West Declination, greatest, April 5¢ 7", +3543; least, May 6412, - 90°29; Range of Declination =126"91. 
Bifilar Magnetometer Reading, greatest, April 54 54, +151-0 Sc. div.; least, May 64 115, — 417-0 Sc. div.; Range of Hor. comp. =0° 05678, 
Balance Magnetometer Reading, greatest, April 54 6, +517°8 Mic. div.; least, May 64 11", —685°5 Mic. div.; Range of Ver. comp. =0" 01141. 
From the Term-Day Observations. 
West Declination, greatest, Feb. 244 11, +1600; least, Sept. 21475, —1655; Range of Declination =32”98. 
Lifilar Magnetometer Reading, greatest, Oct. 184 164, +21-0 Sc. div.; least, Feb. 244 12, —41°3 Sc. div.; Range of Hor. comp. =0°00789. 
Balance Magnetometer Reading, greatest, Feb. 244 11%, +30:9 Mic. div.; least, Sept. 204 16, —148°5 Mic. div.; Range of Ver. comp. =0:00321. 
