Mr. FRANCIS GALTON asked Mr. Buchanan whether, as a rule, in passing from one ocean-current to another, his instruments gave any indication of the change. It was obvious that two adjacent currents must usually have different amounts of salt in their composition, and he would like to know if, with the very delicate instruments used by the Challenger Expedition, and the great precautions which were taken in making the observations, such differences became sensible. Mr. BUCHANAN replied that there was no doubt that in the currents of the ocean there was very considerable difference in the specific gravity of the water, as well as in the temperature. In the chart suspended before the Meeting the Gulf Stream was very clearly indicated simply by the specific gravity, or rather the edge of it, where the warm and dense water of the Gulf Stream met what was called the " cold wall " of the Labrador current. The Equatorial currents also were very marked, being fresh. The Agulhas current of South Africa showed similar variations in density.
(Discussion on) Distribution of Salt in the Ocean
Proceedings of the Royal Geographical Society