587 



Article XIX. 



An extract from Remarks on the Term-Observations /or 1839, 

 of the German Magnetic Association. ^^Wilhelm Weber. 



(With a Plate.) 



[From the ResuUate aus den Beobachtungen des magnetischen Vereins im 

 Jahre 1839.] 



J N concluding this notice, I wish to call attention to the ob- 

 sen'ations made in the high northern latitudes in 1838 and 

 1839, for which we are indebted to the zeal and perseverance of 

 the French savans, MM. Lottin, Bravais and Martin, and of 

 the Swedish naval officers. Lieutenants Siljestrom and Silje- 

 hook, who joined the French expedition to Spitzbergen and 

 Finmarken : we may derive instruction from these observa- 

 tions in regard to the arrangement of future researches of the 

 same nature in those regions. In looking at the Plate, XXVI., 

 it is obvious at the first glance, that the beautiful accordance 

 in the variations of the magnetic elements, which had been hi- 

 therto invariably observed, from Catania, Rome, Milan, &c., to 

 Upsala in the north, ceases when we proceed still further north ; 

 so that in comparing the curves of Upsala and Alten (in Fin- 

 marken, lat. 69° 58') they would scarcely be recognized as be- 

 longing to the same term. There is no doubt as to the correct- 

 ness of the observations, as the voyagers undertook the addi- 

 tional trouble of occasionally observing Gambey's needle simul- 

 taneously with the magnetometer, and the movements of both 

 Mere found to be in accord. If therefore these observations suffi- 

 ciently assure us of the great difference between the magnetic 

 changes in those more northern districts and in Upsala, the im- 

 portant conclusion follows, that future term-observations in these 

 very high latitudes will only be rendered truly valuable by the 

 establishment of intervening stations, which may show the gra- 

 dual passage of the one system of changes into the other ; or by 

 having a group of several stations around Alten and its vicinity, 

 which will afford a sufficient interest by their mutual comparison 

 independently of others, as it is to be expected that great differ- 

 ences should there manifest themselves at small distances. Such 

 observations would be available for inquiries, for which those 



