500 EDITOR'S NOTES. 



which they have thus yielded are most valuable when 

 taken in conjunction with the conclusions from the 

 Hobarton observations; which if they had stood alone 

 might have been deemed indicative of local peculiarity, 

 rather than as affording a distinct hemispherical type. 

 In the present state of our knowledge, or rather in our 

 present deficiency of knowledge, no physical explanation 

 of such a systematic difference of the turning hours in the 

 two hemispheres readily presents itself; and we must 

 therefore consider it as particularly desirable that 

 further investigation should be made of the correspond- 

 ing phenomena in other parts of the middle latitudes 

 of the southern magnetic hemisphere. 



Besides the deflections which occur during the hours 

 of the day there are others, though of much minor 

 extent, which occur during the hours of the night. 

 There is reason to believe that these are in great mea- 

 sure if not altogether produced by the occasional dis- 

 turbances; which, as stated in the preceding note, are 

 now known to be governed in their mean effects by 

 periodical laws, amongst which is one which has for its 

 period a solar day, and has different hours of maximum 

 and minimum from those which have been described as 

 belonging to the regular diurnal variation. But these 

 effects, as well as peculiarities which have been occa- 

 sionally found in the diurnal variation observed in the 

 higher latitudes of the northern hemisphere, and which 

 there is reason to believe are also traceable to the effects 

 of the occasional disturbances in the regions where those 

 effects are the most largely developed, will be more 

 advantageously treated of in a subsequent section. 



