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form by a similar analysis elsewhere ; and so far experience has 

 been in accord with expectation. But, as the forms of these two 

 pair of curves are not only respectively similar, but as they also 

 correspond in the hours at which their chief characteristic features 

 occur, we might also have formed an inference which would have 

 proved erroneous, viz. that the hours as well as the forms would be 

 the same at other stations. Now this is so far from being in 

 accordance with the facts which we already possess, that whilst the 

 forms present generally a marked resemblance, the hours at different 

 stations exhibit every variety. To exemplify this I have given in a 

 third figure the curve of the westerly disturbance- diurnal variation 

 at St. Helena, of which the form is manifestly the same as that of 

 the two curves in fig. 2, whilst the hours of its most marked features 

 exhibit a difference of nearly 1 2 hours of local time from those in 

 fig. 2. 



It may not be unsuitable on the present occasion to take a brief 

 retrospective view of the progress of our knowledge respecting these 

 remarkable phenomena, videlicet, the casual magnetic disturbances, 

 or magnetic storms. Antecedently to the formation of the German 

 Magnetic Association and the publication of its first Annual Report 

 in 1837, our information concerning them went no further than that 

 there occurred at times, apparently not of regular recurrence, extra- 

 ordinary agitations or perturbations of the magnetic needle, which 

 had been noticed in several instances to have taken place contempo- 

 raneously in parts of the European continent distant from each other ; 

 and to have been accompanied by remarkable displays of Aurora, 

 seen either at the locality itself where the needle was disturbed, or 

 observed contemporaneously elsewhere. The opinion which appears 

 to have generally prevailed at this time, was that the Aurora and 

 the magnetic disturbances were kindred phenomena, originating pro- 

 bably in atmospherical derangements, or connected at least in some 

 way with disturbances of the atmospherical equilibrium. They 

 were classed accordingly as " Meteorological Phenomena," and were 

 supposed to have a local, though it might be in some instances a 

 wide, extension and prevalence. 



The special purpose of the German Magnetic Association was to 

 subject the "irregular magnetic disturbances" (as they were then 



