OF THE TOTAL FORCE. 



31 



The amount and range are expressed in parts of the force. The time of the 

 principal maximum and minimum is computed to the nearest one or two minutes. 

 The diurnal range is greatest during summer, and least during winter. The small 

 secondary inflexion obtains only during the winter months ; its range is only about 

 the seventieth part of the larger annual range. 



Table XI contains the principal morning and afternoon epoch of the normal 

 value of the total force. 



The morning epoch is taken from the diagrams ; the afternoon epoch is computed. 



Annual Inequality of tJie Dip and Total Force. The differences of the monthly 

 normals, expressed in parts of the horizontal force, have been taken from Table XII 

 of Part V. The mean of the October and December Values, however, has been sub- 

 stituted for the November value, which produced a correction of +0.00004 to each 

 monthly value to balance the annual sum. The approximate values of the annual 

 inequality of the vertical force are extracted from Part VIII, after converting the 

 scale divisions into parts of the vertical force. 



Table XII contains the values of the annual inequality for the horizontal and 

 vertical components, and, by combination, that of the dip and total force. 



14 



