CHAPTER IV. 



CONCERNING THE INTENSITY OF THE CORPUSCULAR PRECIPITATON 

 IN THE POLAR REGIONS OF THE EARTH. 



75. While discussing the magnetic storms, we have pointed out a number of such storms, 

 affecting the whole earth, which are evidently brought about by electric currents of some kind or other, 

 acting in the region of the auroral zone. The current-system that might explain these storms is often 

 of a very complicated nature, as the magnetic effect round the auroral zone frequently inclines us to 

 believe that there are precipitations of electrically-charged corpuscles over several districts simultaneously 

 all round the auroral zone. 



When the conditions are so complicated, it will be inadvisable to try to obtain a practical result 

 by comparing the magnetic effect of the corpuscles upon the earth with the effect of galvanic currents ; 

 for generally speaking at present a direct calculation of the magnetic effect of the electric corpuscles in 

 different parts of the earth is too difficult of accomplishment. Up to the present, the possible paths 01 

 the electric particles have been found by numerical quadrature; but the actual distribution and density 

 of the rays round the earth have not been found by calculation. The solution of this problem would 01 

 course be of the very greatest importance, if by its means a calculation might be made, from the magne- 

 tic effect upon the earth, of the number of corpuscles emitted by the sun per second. It will be easily 

 understood that the greatest interest will attach to the establishment of the relation between the energy 

 emitted by the sun in the form of corpuscular currents, and the energy sent out in the form of heat and 

 light, more especially for the purpose of deciding whether the amount of the latter energy might possibly 

 have been produced by a disintegration of the sun corresponding to the calculated quantity of corpuscles. 

 At the present standpoint of the theory, however, we must be content with rough calculations and estimates 

 such as those we shall make in the next few articles. 



In certain simple cases, especially during the perturbations that we have called elementary storms, 

 it may, however, be useful to compare the magnetic effect of the corpuscular currents with galvanic 

 currents of so simple a nature that a calculation of the magnetic forces is easy. It may now be regarded 

 as an undoubted fact that in the regions round the auroral zone we sometimes have currents which, at 

 any rate for short distances, have the magnetic effect that a more or less horizontal current above the 

 earth's surface would have, and which is comparatively small in section. 



This is especially shown in the elementary storms that we have considered, where we very often 

 have currents that pass over the earth between Axeleen and Kaafjord. The main intensity of these 

 currents is probably compressed into a comparatively small section, judging from the fact that the 

 vertical components of the perturbing force at the two stations generally have contrary direction, and 

 are of about the same magnitude as the horizontal components. In this case we could compare the 



