238EI.ECTBICHT OF IHE ATMOSPHEKE AND AURORA BOKEALIS. 



which is of great importance. Although, in my theory, tlie terrestrial 

 currents which result from the electric discharges, the cause of polar 

 light, ought to be directed from the north to the south, some are ob- 

 served, either in the telegraph-wires or in their action upon the needle 

 of the compass, which have a contrary direction, that is from the south 

 to the north. The former, it is true, are much the more numerous and 

 the more intense ; but still the latter are apparent from time to time. 

 M. Lemstrom attributes them to the currents of induction, and the elec- 

 tro-motive force which accompanies always the production of an electric 

 spark, as M. Edluud discovered. He considers in fact, and with reason, 

 the electric discharges which constitute polar light, as a series of an in- 

 finite number of sparks, and in this fact found a satisfactory explanation 

 of the existence of currents in an opposite direction from that of the 

 principal current, which is from north to south. 



The perusal of M. Lemstrom's article, while confirming me in the theo- 

 retical views I have advanced in regard to polar auroras, has shown me 

 that there still remain many points to be explained of this interesting 

 subject, especially in what concerns the propagation of electricity in 

 air more or less damp, and reduced to a very low temperature and the 

 influence of a very strong magnetism upon the electric discharges taking 

 place under these conditions. I intend to pursue the subject with dili- 

 gence. 



