in Magnetism and Electricity. 103 



sion of an electric current from a conductor into the earth is 

 invariably accompanied by the electrolyzation of the liquids in 

 contact with this conductor, and that without such electrolyza- 

 tion transmission of an electric current from an electrode into 

 the earth does not occur. 



179. For this reason I have not thought it necessary to make 

 any experiments upon the electric condition of the earth by in- 

 serting electrodes in the ground at different distances from each 

 other, as, owing to the varying degrees of moisture on different 

 parts of the earth's surface, arising from differences of elevation, 

 of climate, and of geological structure, it would be impossible 

 by such means to arrive at any general law on the subject. 

 Moreover, as the normal inductive action of the earth at any 

 given point is, as we have seen, dependent upon the facility with 

 which the liquids in contact with it can be electrolyzed, it follows 

 that the electrolyzation of any liquid artificially introduced into 

 the earth at that point cannot truly represent the amount of dis- 

 charge which the earth is capable of inducing from a given elec- 

 tromotor (116, 176). We can easily understand, therefore, how 

 Matteucci, by establishing communication between his electrodes 

 and the earth by means of a solution of sulphate of copper or 

 other liquids with which he impregnated the ground, and also 

 by a variable degree of saturation of the soil, might obtain those 

 anomalous variations of the earth's resistance which he attributed 

 to differences in the length of the terrestrial matter extending 

 between the electrodes, but which anomalous variations I have 

 not met with in the course of my investigations. 



180. Hitherto all the phenomena which we have observed to 

 attend the passage of an electric current into the earth have been 

 manifested by the heating of wires and by other effects produced 

 at the electromotor ends of the submerged conductors, while the 

 distant ends of the latter were disconnected. I will now proceed 

 to describe some of the effects produced at the distant ends C, D 

 of the conductors when extended separately in the canal and in 

 the sea. 



181. The two naked copper conductors (104) were extended 

 along the bottom of the canal at a sufficient distance from each 

 other to prevent any lateral discharge from taking place between 

 them. A length of about 3 feet of each of the distant ends C, D 

 of the conductors was allowed to project out of the water for the 

 purpose of introducing iron wires or a tangent galvanometer into 

 the circuit. The other ends, A, B, were joined on to the respective 

 polar terminals of the electromotors. 



182. When the current from a single Daniell's cell, or that 



