I' T II E M A (I N i:T [C FORC E. 



I.. 



variation for each month in the year. In like manner \vi obtain the diurnal varia- 

 tion of the horizontal force — free of the larger disturbances — for the summer and 

 winter half, and for the whole year. Table 111. \\i!! exhibit these difference: 

 after their conversion from scale divisions into parts of the horizontal force (one 

 scale division equalling 0.0000365 parts of the horizontal force). The tabular 

 numbers are expressed in units of the sixth place of decimals. A plus sign indi 

 cates a greater force, a minus sign a less force than the mean value. Casting the 

 eye oxer the vertical columns, we obtain also a view of the anjnual inequality of the 

 diurnal variation, which will be examined further on. 



