OP THE DIP AND TOTAL FORCE. 



17 



To render the preceding table uniform with the similar one of the vertical com- 

 ponent, the values at the odd hours will, hereafter, be dropped, their weight is less 

 than one-half of that of the even hours ; the small difference in the times (0.9 m ) will 

 be disregarded, and the values of the dip and total force, immediately deduced from 

 the horizontal and vertical components, will refer to an epoch 21. l m after the full 

 hour. 



For greater completeness, Table III, of Part VIII, is here inserted. 



Solar-Diurnal Variation of the Inclination. The combination of the component 

 values of - and _ to form the corresponding values of the dip is effected by the 



_ 

 Y 



formula 



A0 = sin cos 



AO will be expressed in minutes. 6= 71 59'. A 4- sign indicates an augmenta- 

 tion of the north dip ; a sign the converse. 



3 December, 1864. 



