THE 



PROCEEDINGS 



OF 



ROYAL IRISH ACADEMY. 



MONDAY, NOVEMBER 11, 1861. 



Very B,ev. Dean Graves, D.D., President, in the Chair. 



The Eev, Httmphiiet Lloyd, D.D., read the following paper : — 



On Earth Currents, and their connexion with the Phenomena or 

 Terrestrial Magnetism. 



(Plate I.) 



In the year 1848, Mr. Barlow communicated to the Eoyal Society a 

 Paper On the Spontaneous Electrical Currents observed in the Wires 

 of the Electric Telegraph," in which he established the important fact 

 that a wire, whose extremities are connected with the earth at two 

 distant points, is unceasingly traversed by electric currents, the in- 

 tensity of which varies with the azimuth of the line joining the points 

 of contact with the ground. The direction of these currents was proved 

 to be the same at both extremities of the same wire, and was shown to 

 depend on the relative positions of the earth-connexions, while it was 

 wholly independent of the course followed by the wire itself. The cur- 

 rents cease altogether when either of the contacts with the earth is in- 

 terrupted. Erom these facts Mr. Barlow concluded, that the currents 

 are terrestrial, of which a portion is conveyed along the wire, and 

 rendered visible by the multiplying action of the coil of the galvano- 

 meter." 



Mr. Barlow further observed, that apart from the sudden and occa- 

 sional changes, the general direction of the needle of the galvanometer 

 appeared to exhibit some regularity. He was thus led to institute a 

 series of observations for fourteen days and nights, on two wires simul- 

 taneously, one from Derby to Rugby, and the other from Derby to Bir- 

 mingham, the positions of the needles in both circuits being recorded 



R. I. a. PROC. VOL. VIII. D 



