II. Experimental research on the electromotive force from difference of potential during diffusion in tidal streams

An examination of the composition of the waters throughout the length of a tidal stream during diffusion of salt and fresh water consequent on tidal action, reveals a very considerable difference in the proportion of saline constituents between the water at the surface and that at the bottom, during certain times of tide this difference amounting sometimes to near 100 per cent., and it may frequently be either much greater or less according to tidal fluctuations. This fact constitutes the basis of the investigation which the author undertook, to obtain some approximate quantitative measurement of the resultant electromotive force, &c., arising from such difference of potential. It is known that a current is set up when a bar or plate of the same metal is immersed in two dissimilar solutions in contact, one capable of acting readily upon the metal, the other having little or no action on it, the whole forming a circuit.