514 EDITOR'S NOTES. 



the records at Toronto and Hobarton, that the noc- 

 turnal retrogression is a persistent feature in both 

 hemispheres, and it was at the same time recognised 

 that the hours at which this interruption of the other- 

 wise apparently regular progression took place, were 

 those which were most affected by the disturbances; 

 and that (in both hemispheres), the interruption was 

 precisely such as might be occasioned by them, and 

 might consequently be made to disappear if their 

 influence could be wholly eliminated. The following 

 extract from the first volume of the "Toronto Obser- 

 vations," published in 1845, will show that such was the 

 view taken even at that early period. " The influence 

 of the disturbances must now be regarded as a regular 

 component part of the diurnal variation itself (mean 

 quantities being considered). They now, therefore, 

 pass from the domain of that portion of the observed 

 phenomena to which we give the name of accidental or 

 irregular, (from our present ignorance of the laws which 

 regulate them), to be classed with the other portion in 

 which we recognise laws of order and succession, though 

 as yet we may not be able to assign either causes or 

 precise numerical values. On the one hand we cannot 

 with propriety overlook their influence on the diurnal 

 variation, because though they are of only occasional 

 occurrence, they yet form a permanent and regular 

 part of its mean value ; diminishing (in mean values) 

 the easterly direction of the north end of the mag- 

 net in the forenoon, and increasing it in the evening. 

 On the other hand, it becomes an object of much 

 interest to learn what portion of the diurnal variation is 

 thus due to what is apparently an effect of a distinct 



