394 MAGNETIC STORMS. 



tions were set to Grottingen mean time, (Gottingen being the birth- 

 place of the association,) and the observations were thus rendered 

 strictly simultaneous throughout. The high respect entertained for 

 the eminent persons with whom the scheme of the association origin- 

 ated, obtained for it a very extensive cooperation, not limited to Ger- 

 many alone, but extending over a great part of the European conti- 

 nent. The observations of the "Term-days," as they were called, 

 were maintained until 1841, and were transmitted to Gottingen for 

 coordination and comparison. 



The principal results of this great and admirably conducted coop- 

 erative undertaking were published in works well known to magneti- 

 cians. They may be summed up as follows: The phenomena which 

 were the subjects of investigation were shown to be of casual and not 

 regular occurrence; to prevail contemporaneously everywhere within 

 the limits comprehended by the observations ; and to exhibit a corres-~ 

 pondence surprising! . not only in the larger, but even in almost 



all the smaller oscillations; so that, in the words of the reporters, 

 MM. Gauss and Weber, "nothing, in fact, remained which could 

 justly be ascribed to local causes." 



Equally decided were the conclusions drawn against the previously 

 imagined connection between the magnetic disturbances and derange- 

 ments of the atmosphere, or particular states of the weather. No 

 perceptible influence whatsoever on the needle appeared to be produced 

 either by wind-storms or thunder-storms, even when close at hand. 

 _ The correspondence in the simultaneous movements of the declina- 

 tion magnet, so strikingly manifested over an area of such wide extent 

 was, however, more remarkable in respect to the direction of a pertur- 

 bation than to its amount. The disturbances at different stations, and 

 even, as was expressly stated, at all the stations, coincided, even in 

 smaller instances, in time and in direction, but with dissimilar pro- 

 portions of magnitude. Thus it was found generally that by far the 

 greater number of the anomalous indications were smaller at the 

 southern stations and larger at the northern; the difference being- 

 greater than would be due to the difference in the antagonistic retain- 

 ing force, (i. e., the horizontal force of the earth's magnetism, which 

 is greater at the southern than at the northern stations.) The gener- 

 ality of this occurrence led to the unavoidable inference that in Euroj>e 

 the energy of the disturbing force must be regarded weaker as we 

 follow its action towards the south. 



A close and minute comparison of the simultaneous movements at 

 stations in near proximity to each other led to the further conclusion, 

 also stated to be unavoidable, that "various forces must be admitted 

 to be contemporaneously in action, being probably quite independent 

 of each other, and having very different sources ; the effects of these 

 various forces being intermixed in very dissimilar proportions at 

 various places of observation, according to the directions and distances 

 of these from the sources whence the perturbations proceed." (Besul- 

 tate aus den Beob. des Mag. Vereins; 1836, pp. 99, 100.) The difficulty 

 of disentangling the complications which thus occur at every individual 

 station was fully foreseen and recognized ; and the report, which bears 



