m. C. V. WALKEE ON MAONETIC CALMS AND EAETH-CUEEENTS. 
219 
collected in times of great magnetic disturbance, and those collected during the ordi- 
nary calm periods. 
4th. That the prevailing directions of earth-currents, or the currents of most frequent 
occurrence, are approximately N.E. and S.W. respectively. 
5th. That there is no marked difference in frequency, duration, or value, between the 
N.E. and the S.W. currents. 
6th. That (at least during calm periods) there are definite currents of less frequency 
from some place in the S.E. and N.W. quadrants respectively. 
7th. That the direction of the current in one part of a plane on the earth’s surface 
(at least as far as the S.E. district of England is concerned) coincides with the direction 
in another part of the plane ; and if the dfrection changes in one part, it changes in all 
parts of the plane. 
8th. That the relation in value between currents in a given part of the plane and 
currents in another given part is not constant, but is influenced by local meteorological 
conditions, and varies from time to time. 
9th. That the value of the current of a given length, moving in a given line of direction, 
is not necessarily the same as that of a current of the same length on the same line of 
direction produced, and that their relative value depends on the physical character of 
the earth interposed between the respective points of observation, and is tolerably con- 
stant. 
10th. That the currents which have formed the bases of these investigations are 
derived currents from true and proper earth-currents, and neither in whole nor in any 
appreciable part have been collected from the atmosphere, nor are due either in whole 
or in any appreciable part to polarization imparted to earth-plates by the previous 
passage of earth-currents or of powerful telegraphic currents; nor are they due to any 
electromotive force in the earth-plates themselves. 
11th. That the earth-cmnents in question (at least the powerful currents present at 
all times of great magnetic disturbance) exercise a direct action upon magnetometers, 
just as artificial currents confined to a wire exercise a direct action upon a magnet. 
