VI 



CONTENTS. 



NO. 



PAGE 



Horizontal Component of Magnetic Force — 



Horizontal Component in Absolute Measure, 48 xxx 



Secular Change from Observations of Absolute Measure, 49 xxx 



Mean Values of the Variations of the Horizontal Component 51 xxxi 



Comparison of the Secular Change from Observations of Absolute Measure 



with that from Observations of the Bililar Magnetometer, 53 xxxii 



Effect of Disturbance on the Mean Value, 54 xxxii 



Secular change employed in Deducing the Annual Variations, 55 xxxii 



Annual Variations — 



Mean Horizontal Component, 56 xxxii 



Foot-note on the Annual Period Deduced from the Observations at Toronto 



and Munich, xxxii 



Eifect of Disturbance on the Monthly Means, 57 xxxiii 



Mean Horizontal Component from Undisturbed Days, 58 xxxiii 



Differences of the Daily Means from the Monthly Means, 59 xxxiv 



Diurnal Ranges, 60 xxxv 



Ranges of the Monthly Mean Diurnal Variation, from all the Observations 



and from Selected Days, 61 xxxv 



Mean Difference of an Observation from the Monthly Mean, 63 xxxv 



Probable Error of an Observation of the Horizontal Component, 64 xxxau 



Number of Observations greater than the Monthly Mean, 65 xxxvi 



Monthly Variations — 



Mean Horizontal Component, 66 xxxvi 



Diurnal Ranges, 67 xxxvii 



Mean Difference of an Observation from the Monthly Mean, 68 xxxvi i 



Diurnal Variations — 



Results from all the Observations, for each Month, 69 xxxviii 



Results from all the Observations, for Groups of Months, 70 xxxix 



Results from Undisturbed Observations, for Groups of Months, 71 xl 



Effect of Disturbance on the Hourly Means, 72 xl 



Frequency of Positive and Negative Departures from the Hourly Mean 



Positions, 74 xlii 



Mean Difference of an Observation from the Hourly Mean Position for 



each Hour, • 76 xlii 



Probable Error of an Observation from the Monthly Mean, 78 xliv 



Variations with reference to the Moon's Hour-Angle, 79 xliv 



Vertical Component of Magnetic Force — 



Vertical Component in Absolute Measure, 81 xlv 



Adjustment of Balance Magnetometer in different Years, 82 xlv 



Yearly Means of the Variations of the Vertical Component with the Secu- 

 lar Change, 83 xlvi 



J, Effect of Disturbance on the Yearly Mean, 85 xlvi 



