Or 
VERTICAL COMPONENT OF MAGNETIC FORCE. xlv 
80. The result for the winter lunations of 1844 agrees with this, in shewing a maximum immediately after 
the inferior transit ; but differs from it in having the minimum about the hour of the second maximum for the 
other periods ; this difference, it is conceived, is chiefly the effect of disturbances, as has been found when the 
larger disturbances were eliminated. (See the volume for 1844, p. 365.) 
VERTICAL COMPONENT OF MAGNETIC FORCE. 
81. Observations for the absolute value of the vertical component were made in 1846 in the manner 
described in the Introduction to the Observations for 1844, p. liti. (foot-note), but they have not been reduced ; 
indeed, it is doubtful whether the dimensions of the magnets employed, and the errors of the instrument were 
likely to admit a sufficiently accurate result. We may deduce the absolute value of the vertical component 
from the observations for the horizontal component and magnetic dip; assuming the latter =71° 15’ for the 
year 1845, we find the mean value of the former from the observations with the large deflecting bar (last 
column of Table 21) for the year 1845 =3-3837 ;—whence the absolute value of the vertical component of 
magnetic force for 1845 =9:9680, The following results are deduced wholly from the observations of the 
balance magnetometer : the variations are given in parts of the whole vertical component assumed equal to unity. 
TABLE 38.—Monthly Means of the Variations of the Vertical Component of Magnetic Force at 
Makerstoun. 
Month. 1842. 1844. 1845. 1847. 1848. 
January 012155 | -009905 | -007838 | -005904)| -003917| -002523 |[-001880]| -001157 
February -011988 | -009708 | 007458 | -005616)| -003737 | -002636) .001800| -001004 
March -011495 | -009325 | .007341 | -005475| -003663 | -002659| -001684| -000747 
April -011446 |) -008992 | -007384| -005361| -003526| -002668| -001379| -000537 
May -011323 | -008804 | -007062| -005192) -003603| -002599)| -001085| -000472 
June -011167 | -008878| -006847 | -005034| -003936| -002488 | -000936| -000467 
July ‘010883 | -008732| -006552| -004740| -003839| -002415| -001561] -000314 
August -010797 | -008562 | -006341 | -004643 | -003678| -002184| -001197| -000079 
September -010672) -008158 | -006267 | -004534)| -003584]| -002141| -000705| -000129 
October -010471 | -008138}| .006129 | -004310| -003206| -002299| -001354] -000127 
November -010355 | -008109 | -006155 | 004307 | -002899| -002344| -001361 | -000109 
December -010129 | -007992| -006003 | -004315| -002643 | -002168| -001346| -000017 
82. Table 38 contains the monthly means of the balance magnetometer readings, as deduced from the regular 
daily observations ; these in 1848 and 1849 were only two daily. From 1842 to 1847 the balance needle 
oceupied a position at right angles to the magnetic meridian ; in 1848 and 1849 its position was in the mag- 
netic meridian. The monthly means diminish with a few exceptions from month to month throughout the 
whole period. ‘The yearly means of the variations and secular changes are given in Table 39. 
TABLE 39.—Yearly Means of the Variations of the Vertical Component of Magnetic Force, 
with the Secular Change. 
Mean of Secular Change. 
Variations 
f Vertical i 
Golipottent. Year to Year. | Mean of Hach | During Hach 
Four Years, Year. 
0-011073 0:002327 
-008774 0:002299 2108 
-006781 1993 1966 
-004953 1828 1733 
003519 1434 0-001888 1151 
-002427 1092 1587 1077 
001357 1070 1356 0867 
000430 0927 1131 1125 
