CONTENTS. 
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Annual Variations — 
Mean Vertical Component,-. 86 
Mean Change of the Vertical Component from Month to Month, 88 
Effect of Disturbances on the Monthly Means, 89 
Difference of the Daily Means from the Monthly Means, 90 
Diurnal Ranges, 91 
Ranges of the Monthly Mean Diurnal Variations from all the Observations, 
and from Selected Days, 92 
General Law of the Ranges of the Undisturbed Mean Dim-nal Variation, 93 
Mean Difference of an Observation from the Monthly Mean, 94 
Number of Observations greater than the Monthly Mean, 95 
Monthly Variations — 
Mean Vertical Component, 96 
Diurnal Ranges, 97 
Mean Difference of an Observation from the Monthly Mean, 98 
Diurnal Vamations — 
Results from all the Observations, for each Month 99 
Results from all the Obsei-vations, for Groups of Months, 100 
Results from Undisturbed Observations, for Groups of Months, 101 
Effect of Disturbance on the Hourly Means, 102 
Frequency of Positive and Negative Departures from the Hourly Mean 
Position, 104 
Mean Difference of an Observation from the Monthly Mean Position for 
each Hour, 105 
Mean Difference from Undisturbed Mean Positions for each Hour, 108 
Variations with reference to the Moon's Hour- Angle, Ill 
Magnetic Dip — 
Places of Observation for Different Epochs and General Remarks, 113 
Observations in 1849 on Original Dip-Pillar, •. 114 
Observations to determine Local Error, 115 
Secular Change, 116 
Result of Observations with Inclinometer in different Azimuths, 117 
Observations with the Inclinometer of the Royal Society of Edinburgh, ••• 118 
Variations of Magnetic Dip, ded/uced from the tivo Component Magnetometers — 
Similarity between Results for Magnetic Dip and for Horizontal Com- 
ponent, - 119 
Secular Change, 120 
Effect of Disturbance on the Yearly Mean, 121 
Annuaf Period, from all the Observations, • 122 
Annual Period, from Undisturbed Observations, 123 
Annual Variation of Ranges of Monthly Mean Diurnal Variation, 124 
Variations of Magnetic Dip with the Moon's Age, ••• 125 
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