CONTENTS. 



NO. 



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 Diurnal 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 Variations — 



Results from all the Observations, for each Month 99 



Results from all the Observations, 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 Undistvirbed Mean Positions for each Hour, 108 



Variations Avith 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 diflFerent Azimuths, 117 



Observations with the Inclinometer of the Royal Society of Edinburgh, ••• 118 



Variations of Magnetic Dip, deduced from the two 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 



Annual Period, from all the Observations, • 122 



Annual Period, from Undisturbed Observations, 123 



Annual Vaviation of Ranges of Monthly Mean Diurnal Variation, 124 



Variations of Magnetic Dip with the Moon's Age, 125 



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