POTENTIAL AND EARTH CURRENTS. 187 



The line being disconnected from the batteries, and 

 connected with the earth at both ends, the current was 

 obtained from the earth alone, independent of any artifi- 

 cial source: and its strength and direction, as indicated by 

 the galvanometer, were noted, and also the temperature. 



It was found, that the general direction of the cur- 

 rent was from a region of high to one of low temper- 

 ature, though frequent reversals of current were 

 observed. And as the east, from longer exposure to 

 the sun's heat, would have a higher temperature than 

 $he west, at the time of the morning observation, the 

 prevailing current, at this hour, was found to be from 

 east to west. As these conditions of temperature 

 would be reversed in the evening, the observations at 

 that hour showed a corresponding reversal, and a ' 

 prevailing west to east current. While the observa- 

 tions near midnight, when another reversal of temper- 

 ature is at hand, showed that the current then was 

 fluctuating and uncertain. 



The deflection of the galvanometer needle varied 

 from to 57; the morning average being 11.4, the 

 evening average 14.3, the average near midnight 7.3, 

 and the general average 11. The difference of tem- 

 perature, between the points of observation, varied 

 from to 37; the morning average being 14.5, the 

 evening average 9.5, the average near midnight 10.3, 

 and the general average 11.4. 



When the earth connection was severed, at either 

 station, the current was reduced to a minimum ; cor- 

 responding to the probable leakage along the line ; 

 proving that it was an earth current, and not an 

 atmospheric current. 



If a similar east and west line were extended rouna 



