“ At Freiberg he was charged with the preparation of a geological map of Saxony, which he carried out with the aid of Bernhard von Cotta in 1846. He was a man of encyclopaedic knowledge, lucid and fluent as a teacher. Early in life (1821–1822) he travelled in Norway, and his observations on that country, and his subsequent publications on crystallography, mineralogy and geology established his reputation. ”