Sheet Discussing Tides and Water Movement from Codex Leicester by Leonardo da Vinci

(Original Caption) : Sheet 6B: Folio 6v is devoted to the study of "flow and ebb" of water and how sediment, including shells and fossils, circulates in the body of the earth. The facing page continues this discussion and raises the issue of the varying distances of seas and mountains from the center of the earth. 6v SYNOPSIS: The ebb and flow of water in both seas and rivers is one of Leonardo's guiding themes in the Codex Leicester. He discusses variations in the tides based on time differences around the globe: "All seas have their flow and ebb in the same period, but they seem to vary because the days do not begin at the same time throughout the universe. . . . When it is midday in our hemisphere, it is midnight in the opposite hemisphere." He also considers a number of physical variables that act upon water, including the action of the wind. He is here interested in developing (Photo by Seth Joel/Corbis/VCG via Getty Images)