The oceans are constantly in motion; flowing, streaming, engulfing things in one place, only to disgorge them in another. When Georg Neumayer sent his bottle messages adrift in the nineteenth century, he was by no means just doing it as a pastime. The German scientist and hydrographer was collecting information on the ocean currents. The first of his numerous bottles was launched from a ship off Cape Horn in 1864; it was later found on the south coast of Australia and returned to Neumayer. With the information he gathered, Neumayer was able to publish an Atlas of the Atlantic Ocean in 1892 with data on currents, water temperature, depths, and other oceanographic and meteorological conditions. When his sailing directions were published as reprints in the 1990s, they were still the best information available. Knowledge about the motions of the waters is still important today—small vortices and whirlpools, as depicted here by marbling with shaving cream, can be dangerous to swimmers and vessels, while big currents and gyres such as those in the North Atlantic Drift are important factors for the entire climate system.
Sources: Machoczek, Detlev: Georg Balthasar von Neumayer, “Marine Sciences in Service of Sea Trade. Proceedings of the Royal Society of Victoria 123, (2011).