The mean azimuth of this current appears to bo connected with the 

 magnetic meridian of the place, to which it is nearly perpendicular. 

 This will appear from the following Table of the mean azimuths of the 

 disturbance- currents at the northern stations, measured from the astro- 

 nomical and from the magnetical meridians, respectively : — 



Places. 



Az. (Astron.) 



Az. (Magn.) 





45° 



72^ 



Makerstoun, . . . 



51 



76 



Munich, 



62-5 



69 





81-5 



83 



Athabasca, .... 



110 



81 



The mean azimuth (magnetic) for the five stations is E. 14° The 

 mean azimuth of the two stations in the Southern hemisphere is E. 1 1° S., 

 deviating nearly as much to the south, as that of the northern stations 

 deviates in the opposite direction. It thus appears that while the prin- 

 cipal current is eastward in both hemispheres, there is also a meridional 

 current tending northward in the l^orthern hemisphere, and southward 

 in the Southern. Its intensity is between one-fourth and one-fifth of 

 that of the other component. 



These results are wholly at variance with the hypothesis imagined by 

 M. dela Kive in explanation of the phenomena of magnetic disturbances, 

 according to which the disturbance-current flows from north to south 

 onl}^'^' 



The diurnal changes of the intensity of the disturbance-currents pre- 

 sent features equally marked. In order to perceive them clearly, it may 

 be convenient to examine separately the meridional currents, and those at 

 right angles to the magnetic meridian. 



The meridional currents are developed chiefly at the European sta- 

 tions, and at Toronto, in Canada : at Athabasca, and at the southern 

 stations, they are comparatively small. The northerly maximum occurs 

 at Toronto at 9 p. m., at Munich at 10 p. m., and at Dublin at 11 p.m. 

 Its epoch at Makerstoun is between 9 p. m. and 11 p. m. The southerly 

 maximum occurs at 8 a. m., very nearly, at the four stations. Thus the 

 epochs are nearly at the same hours of local time, notwithstanding the 

 differences of longitude. 



A similar result appears from an examination of the currents at right 

 angles to the magnetic meridian. Thus, in the northern hemisphere, the 

 easterly maximum occurs between 2 a. m. and 4 a. m., and the westerly 

 maximum (or easterly minimum) between 3 p. m. and 5 p. m. The two 

 epochs are precisely the same at Makerstoun and at Toronto, places which 

 differ more than five hours in longitude. 



* The discrepancy of M. de la Rive's hypothesis with the phenomena of the Earth- 

 currents, as observed in the British Islands, has been already pointed out by Mr. Walker. 

 It is even more marked at other parts of the globe. 



