XVi INTRODUCTION TO THE MAKERSTOUN 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. 
Unifilar, minus 
Declino- | Upigiar 250 Se. Div., 
meter reduced to the 
Reading. Declinometer Direct Inverted 
MINUS Us plus u. 
Declinometer Reading. | Mean of | Reading 
two direct 
or 
inverted. 
Position of 
Magnet. 
Reading. 
d. h. . Div. Se. Div. Se. Diy. Se. Diy. 
July 31 3} Direct : 142-49 |- 
Inverted : 154-58 
Direct : 140-13 
Inverted : 154-07 
Direct . 138-06 
Inverted : 157-35 
Direct : 136-69 
Direct : 137-45 
Inverted 
Direct . 137-79 
Direct . 138-82 
Inverted “ 
Direct . 139-73 
Direct - 141-18 
Inverted : : 
Direct : 141-31 
Inverted : 
Direct : 140-69 
The mean reading of the short scale for the magnetic axis = 147-11. 
Corrections to be applied to the Scale Readings at the Magnetic Awis 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. 4. 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°79 and + 0°80 long scale divisions, on the respective occasions. 
