Elizabeth Cary Agassiz, Louis Agassiz: his life and correspondence, third edition

While Agassiz's various zoological works were thus pressed with unceasing activity, the glaciers and their attendant phenomena, which had so captivated his imagination, were ever present to his thought. In August of the year 1838, a year after he had announced at the meeting of the Helvetic Society his comprehensive theory respecting the action of ice over the whole northern hemisphere, he made two important excursions in the Alps. The first was to the valley of Hassli, the second to the glaciers of Mont Blanc. In both he was accompanied by his scientific collaborator, M. Desor, whose intrepidity and ardor hardly fell short of his own; by Mr. Dinkel as artist, and by one or two students and friends. These excursions were a kind of prelude to his more prolonged sojourns on the Alps, and to the series of observations carried