When did Louis Agassiz begin studying Swiss glaciers?

Louis Agassiz began his intensive field studies of Swiss glaciers following his 1837 address to the Helvetian Society, which proposed the theory of a past ice age. By 1840, he published his findings in Études sur les glaciers ("Studies of Glaciers"), which demonstrated the historical extent of Alpine glaciers. Additionally, during the early 19th century, Louis Agassiz conducted research on the movement of these glaciers, observing that their velocity was fastest in the central regions.12