xvi 
Introduction to the Makerstotjn Observations, 1843. 
The zero used for the observations 1841 and 1842=255-2 (Introduction, 1841-2, 
Table 4), was used till Jan. 13. 1843, after which the previous determination was 
taken, as it was conceived that some change might have occurred at that date in a 
slight adjustment of the appendages of the magnet, made for the purpose of balanc- 
ing it. 
2. Observations with the Short Scale. 
Table 4. — Short Scale Reading at the Magnetic Axis of the Declination Magnet. 
Date. 
Position of 
Magnet. 
Declino- 
meter 
Reading. 
... 
U miliar 
Reading. 
TJnifilar, minus 
250 Sc. Div., 
reduced to the 
Declinometer 
— u. 
Declinometi 
Direct 
minus u, 
!r Reading. 
Inverted 
plus u. 
Mean of 
two direct 
or 
inverted. 
Reading 
for 
Magnetic 
Axis. 
d. 
h. 
Sc. Div. 
Sc. Div. 
Sc. Div. 
Sc. Div. 
Sc. Div. 
Sc. Div. 
Sc. Div. 
July 31 
3 
Direct 
148-91 
257 15 
+ 6-42 
142-49 
148-53 
Inverted 
147-16 
258-27 
7-42 
154-58 
Aug. 
2 
0 
Direct 
149-24 
260-15 
9-11 
140-13 
Inverted 
146-37 
259-70 
8-70 
15407 
139-10 
146-58 
Direct 
144-51 
257-18 
6-45 
138-06 
Aug. 
2 
3 
Inverted 
148-90 
259-41 
8-45 
157-35 
Direct 
145-75 
260-10 
9-06 
136-69 
147-02 
Aug. 
3 
0 
Direct 
146-06 
259-60 
8-61 
137-45 
Inverted 
150-71 
255-50 
4-94 
155-65 
137-62 
146-63 
Direct 
142-04 
254-74 
4-25 
137-79 
Aug. 
3 
4 
Direct 
142-66 
254-28 
3-84 
138-82 
Inverted 
149-50 
255-46 
4-90 
154-40 
139-27 
146-83 
Direct 
145-78 
256-74 
6-05 
139-73 
Aug. 
3 
7 
Direct 
157-15 
267-80 
15-97 
141-18 
Inverted 
136-95 
268-38 
16-49 
153-44 
141-24 
147-34 
Direct 
157-38 
267-92 
16-07 
141-31 
153-01 
147-16 
Inverted 
137-51 
266-81 
15-08 
152-59 
141-00 
146-S0 
Direct 
155-88 
266-93 
15-19 
140-69 
The mean reading of the short scale for the magnetic axis = 147'H. 
Corrections to be applied to the Scale Readings at the Magnetic Axis of the Declina- 
tion Magnets, in order to obtain the zeros of the scales. 
11. Correction for the effects of the bifilar and balance magnets on the read- 
ings of the declination magnet. 
The effect of the bifilar magnet (by Table 5. of the Introduction to the Obser- 
vations for 1841 and 1842, north end west) = - 0-64 long scale divisions. 
Sept, I. 1843, and Jan. 25. 1844. The balance magnet was removed for the 
purpose of determining its temperature co-efficient. Its effect (north end east) was 
found = + 0-7! > and + 0*80 long scale divisions, on the respective occasions. 
