In 1860, he made a second visit to Europe, and made a tour of geological study in the southern United States. In the next year, he traveled through Ireland, Scotland, the Netherlands, Belgium, and a part of Germany, and spent a semester in Göttingen in the study of geology and mineralogy, under Waltershausen. He then visited and studied the volcanic regions of Italy, ascended Mount Vesuvius, explored the regions of the solfatara, climbed Mount Etna, examined the glaciers of Switzerland and the configuration of the Alpine regions; and, in France, inspected the natural curiosities of the Puy-de-Dôme.