VARIATIONS OF THE MAGNETIC NEEDLE. 



293 



II. In the southern hemisphere, so far, at least, as may be 

 inferred from the phenomena at Hobarton, the rotation of the 

 currents is in the opposite direction to that in the northern. This 

 will be best seen by a comparison of the annexed diagrams (Figs. 

 1 and 2) , which represent the directions of the currents at the several 

 hours at Toronto, and at Hobarton, places which have equal lati- 

 tudes north and south. 



It appears, therefore, that the point to which the earth-current 

 is directed in all cases follows the sun, although at unequal intervals 

 at the different periods of the day. 



III. The hour at which the force of the current is greatest, in 

 the northern hemisphere, ranges between noon and 2 p. M., being 

 earliest in the British Islands, and latest in Western Siberia. Its 

 change with longitude will be understood from the following : 



Western Europe, hour of maximum = 12 h 30 m r. M. 



Central Europe, 

 Eastern Europe, 

 Western Siberia, 

 Central Siberia, 

 Eastern Siberia, 

 Canada, 





 35 







55 

 40 

 15 



The men n tim<' of the maximum is l h 25 m r. M. 



IV. The minimum, of current intensity during the night takes 

 } 'lace at an interval of about twelve hours from the epoch of the 

 maximum; and the directions of the yn-nli f an-l /< tui currents are, 

 in nearly all cases, exactly 



