A portrait of Alexander von Humboldt in his study

A scene of Alexander von Humboldt (1769-1859) at work in his study, taken from a watercolour by fellow Prussian Eduard Hildebrandt (1818-68), executed when the famed explorer was nearly eighty. The facsimile hand writing states that it is a true representation of his study while he was writing his treatise 'Kosmos' (a term he reintroduced from ancient Greek).
The explorer and painter had become friends, and Humboldt had been able to introduce Hildebrandt to some important clients: Hildebrandt's first trip to America was to paint Rio de Janeiro for Friedrich Wilhelm IV of Prussia. This led to a world tour, 1860 - 1862, which included stops in the Middle East, India, Singapore, Thailand, Macao, Hong Kong, China, The Philippines, Japan and the United States. A folio of his works from his round-the-world voyage were published as chromolithographs in 1864 in Berlin under the title of 'Reise Um Die Erde' (Journey around the Earth).