A German naturalist and explorer, Humboldt traveled extensively and made observations and discoveries too numerous to count. Among other things, he discovered the connection between the Amazon and Orinoco river systems, surmised that lack of oxygen causes altitude sickness, studied the ocean current off the western coast of South America that was known for a time as the Humboldt Current, and added to an understanding of the development of the Earth’s crust. To what did he devote his final years? Discuss