396 MAGNETIC STORMS. 



by the declaration that "the theory of the transitory changes is in 

 itself one of the most interesting and important points to which the 

 attention of magnetic inquirers can be turned, as they are, no doubt, 

 intimately connected with the general causes of terrestrial magnetism, 

 and will probably lead us to a much more perfect knowledge of these 

 causes than we now possess." 



The instructions contained in the Eoyal Society's report for the ad- 

 justment and manipulation of the several instruments provided for 

 these purposes, were clear, simple, and precise. In looking back upon 

 them after the completion of the services for which they were designed, 

 it is impossible to speak of the instructions otherwise than with un- 

 qualified praise. But the guidance afforded by the instructions term- 

 inated with the completion of the observations. To have attempted 

 to prescribe the methods by which conclusions, the nature of which 

 could not be anticipated, should be sought out from observations 

 not yet made, would have been obviously premature. Yet without 

 some discussions of the results, the mere publication of unreduced ob- 

 servations is comparatively valueless. It has been well remarked by 

 eminent authority, whose opinions expressed in the Royal Society's 

 report have been frequently referred to in the course of this paper, 

 that "a man may as well keep a register of his dreams as of the 

 weather, or any other set of daily phenomena, if the spirit of grouping, 

 combining, and eliciting results be absent." It was indispensable that 

 the attempt should be made to gather in at least the first fruits of an 

 undertaking on which a considerable amount of public money and of 

 individual labor had been expended; and the duty of making the 

 attempt might naturally be considered to rest on the person who had 

 been intrusted with the superintendence of the Government observa- 

 tories. The methods and processes adopted for reducing, combining, 

 eliminating, and otherwise eliciting results, were necessarily of a novel 

 description ; they were, in fact, an endeavor to find a way by untrodden 

 paths to simple and general phenomenal laws, where no definite 

 knowledge of the origin or mode of causation of the phenomena previ- 

 ously existed. Happily, it is not necessary to trespass on the time or 

 attention of the society by a description of the methods and processes 

 which have been employed to elucidate some of the leading features of 

 the magnetic storms, as these are fully described in the discussions 

 prefixed to the ten large volumes in which the observations at the 

 colonial observatories have been printed. It will be only necessary 

 to advert, and that very briefly, to some of the principal conclusions 

 which may be supposed to throw most light on the theory of these 

 phenomena. 



The results of the extension of the term-day comparisons to the 

 American continent, and to the southern hemisphere and the tropics, 

 may first be disposed of, in a very few words. The contemporaneous 

 character of the disturbances which had been shown by the German 

 term observations to extend over the larger portion of the European 

 continent, manifested itself also in the comparisons of the term-days 

 in 1840, 1841, and 1842, at Prague and Breslau, in Europe, and To- 

 ronto and Philadelphia, in America, published in 1845 ; and the same 



