ELECTRICAL CURRENTS OF THE EARTH. 



223 



It is proper to add that at the two stations of Aosta and Courinayeur, 

 two electrodes of copper were also in operation, consisting of two plates 

 of that metal, with a surface of about a third of a square metre, and 

 buried at a dei^th of about one metre. These plates were employed as 

 electrodes after having- been buried for two days. On the day of the 3d 

 of November, with these electrodes of copper, and at intervals of some 

 hours, there was a nearly lixed deviation in the same direction with 

 those of the electrodes of zinc, and indicating, from 12 o'clock to 1-J.48, 

 successively (>5o, 70°, 09^, and from i>.40 to sr^O, G9^ and GS^. All the 

 deviations above reported indicated «n ascending current in the metallic 

 portion of the circuit. 



I shall only cite, in addition to the above, the experiments made on 

 the line between Ivrea and Aosta, having a length of about IGO kilo- 

 metres, (1)9 miles,) and a difference of level between the extremities ecpial 

 to 3G4 metres, (1,194 feet.) These experiments were conducted precisely 

 like those just described at length, between Aosta and Courmuyeur, 

 and were executed during the days of the 5th and Gth of November. 

 The atmospheric electricity, always positive, was at Aosta considerably 

 more intense than in the experiments made at Courmayeur. 



The current which circulated in this line was constantly an ascending- 

 one in the metallic part of the circuit, and for many hours the deviation 

 oscillated betw^een 40° and 50°. On the second day the air waw per- 

 fectly serene, the sun lustrous, and the signs of atmospheric electricity 

 constantly progressive. The needle remained deflected for several 

 hours, and apparently fixed between G0° and Gl^ by an ascending cur- 

 rent in the metallic line. Here also the plates of copper, sunk in the 



