Disturbances of Magnetic Declination in the Kew Observatory. 321 



attempted to prescribe the methods by which conclusions, the nature 

 of which could not be anticipated, should be sought out from observa- 

 tions not yet made, would have been obviously premature. Yet 

 without some discussion of the results, the mere publication of un- 

 reduced observations is comparatively valueless. It bas been well 

 remarked by an eminent authority, whose opinions expressed in the 

 Royal Society's lleport 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 labour had been expended ; and the 

 duty of making the attempt might naturally be considered to rest on 

 the person who had been entrusted with the superintendence of the 

 Government Observatories. The methods and processes adopted for 

 reducing, combining, eliminating, and otherwise eliciting results were 

 necessarily of a novel description ; they were in fact an endeavour 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 previously 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 en 

 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 contem- 

 poraneous 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 andBreslau in Europe, 

 and Toronto and Philadelphia in America, published in 1845; and 

 the same conclusion was obtained by comparing with each other the 

 term-days at the Colonial Observatories, situated in parts of the globe 

 most distant from one another. The days of disturbance still appeared 

 to be of casual occurrence, but were now recognized as affections com- 

 mon to the whole c/lobe, showing themselves simultaneously at stations 

 most widely removed from each other. When distant stations were 

 compared, as for example stations in Europe with those in America, 

 and either or both with Tasmania, discrepancies in the amount of par- 

 ticular perturbations, similar to those which had been found in com- 

 paring the European stations with each other, presented themselves, 

 but larger and more frequent, and extending occasionally even to the 

 reversal of the direction of the simultaneous disturbance. Instances 

 were not unfrequent of the same clement, or of different elements, 

 being disturbed at the same observation- instant in Europe and 



