In any retrospect of scientific progress there are always special points, ‘golden milestones,’ along the road by which we travel, which mark unusual stages in our journey. Zittel, in his “History of Geology and Palæontology,” fixes the ‘heroic period’ from 1790 to 1820, when the great masters of our science, Werner, Pallas, Saussure, Huttoti, Playfair, William Smith, Leopold von Buch, Alexander von Humboldt, Alex. Brongniart, and Cuvier arose and laid the foundations of Geology.