70 



As soon as this circuit is closed the galvanometer 

 shows a deviation, the cause of which is twofold: the one 

 is that the metallic plates in touching the soil produce an 

 electroraotive force (EMF), the other is the EMF of the 

 electricäl earth-current. The former is nearly constant, the 

 latter generally very variable. Airy as well as Lamont had 

 in view only the variations of the earth-currents and at the 

 beginning these were even the most important. 



The results of these researches were considerable. 



The first that neither the magnetic state of the earth 

 nor the periodic variations could be explained through the 

 earth-currents. 



The second was that the magnetic disturbances or 

 storms are in a very intimate relation to the variations in 

 the earth-currents, yet the latter are both more numerous 

 and occur a short time before the former or the magnetic 

 perturbations. This short interval is not quite determined 

 but ought to be of about 5 minutes. Ary says „that one 

 cannot, in regarding the curves, which represent the 

 simultaneous observations of the both phenomena, avoid the 

 conclusion that the magnetic perturbations have their cause 

 in the galvanic earth-currents". 



The question of the earth-currents was in about this 

 state, when we had occasion to add a little to our know- 

 ledge of them. 



During a short expedition to finnish Lapland 1871 

 we had for the first time occasion to make researches of 

 the earth-currents in the polar-regions. The investigations 

 were executed at two places: in Kittilä (lat. 67° 40', long. 

 34° 53',2) from the middle of October to the beginning of 

 November and in Enare (lat. 68° 55', long. 27° 10',3) near 

 the church, from 15—25 November. The method was the 

 same as Lamonts, but with plates ot platina. The observa- 

 tions are published, in the Vol. III of the „Exploration etc." 

 above mentioned, together with the observations on the 

 earth-currents. The results were briefly the following: In 

 Kittilä the galvanometer with astatique needles showed de- 



