MAGNETIC STORMS. 395 



the initial of M. Gauss, concludes with the remark that "it will he a 

 triumph of science, if at some future time we should succeed in reduc- 

 ing into order the manifold intricacies of the combinations, in separat- 

 ing from each other the several forces of which they are the compound 

 results, and in assigning the source and measure of each." 



Such was the state of the inquiry when it was entered upon by the 

 Royal Society. The report of the Committee of Physics, drawn up 

 (inter alia) for the guidance of the Magnetic Observatories established 

 by her Majesty's government for a limited period in four of the British 

 colonies, bears date in 1840. The objects proposed by this report were 

 a very considerable enlargement upon those of the German Association, 

 as well as an extension of the research to more distant parts of the 

 globe. The German observations had been limited, for the most part, 

 to one only of three elements required in a complete investigation. 

 When the German Association commenced its operations, the declina- 

 tion was the sole element for which an apparatus had been devised 

 capable of recording its variations with the necessary precision. To 

 meet the deficiency in respect to the horizontal component of the mag- 

 netic force, M. Gauss constructed, in 1837, his bifilar magnetometer, 

 which was employed at Gottingen, and at some few of the German 

 stations, concurrently with the declinometer, in the term observations 

 of the concluding years of the association. But an apparatus for the 

 corresponding observations of the vertical portion of the force was, as 

 yet, wholly wanting ; without such an apparatus as a companion to 

 the bifilar, no determination could be made of the perturbations or 

 momentary changes of the magnetic dip and force; and, without a 

 knowledge of these, no satisfactory conclusion in regard to the real 

 nature, amount, and direction of the perturbing forces could be ex- 

 pected. The ingenuity of Dr. Lloyd supplied the desideratum by 

 devising the vertical-force magnetometer, which, with adequate care, 

 has been found scarcely, if at all, inferior to the bifilar in the perform- 

 ance of its work. The scheme of the British observatories was thus 

 enabled to comprehend all the data required for the investigation of 

 the casual disturbances, whether that investigation was pursued as 

 before by concerted simultaneous observations at different stations, or, 

 as suggested in the report, by the determination of the laics, relations, 

 and dependencies of the disturbances at individual stations, obtained 

 independently and ivithout concert with other observers or other stations. 

 Thus, in reference to these particular phenomena, the British system 

 was both an enlargement and an extension of the objects of the Ger- 

 man Association ; but it also embraced within its scope the determina- 

 tions with a precision, not previously attempted, of the absolute values 

 of the three elements, and of the periodical and progressive changes to 

 which they are subject; premising, however, and insisting with a 

 sagacity which has been fully justified by subsequent experience, on 

 the necessity of eliminating, in the first instance, the effects of the 

 casual and transitory variations, as- an indispensible preliminary to a 

 correct knowledge and analysis of the progressive and periodical 

 changes. A further prominency was given to investigations into a 

 particular class of phenomena, which form the subject of this paper, 



