THE MAGNETIC FIELD PRODUCED BY EARTH CURRENTS FLOWING IN AN ESTUARY OR SEA CHANNEL

Records made in the Clyde estuary of fluctuations of the Earth's magnetic field, and of simultaneous fluctuations in the horizontal potential gradients in the water, give a clear indication that the fluctuationsin vertical intensity are largely due to a varying flow of electric current in the sea. Variations in the Earth current in the English Channel appear to produce appreciable fluctuations in vertical intensity at the magnetic observatory at Abinger.