MY predecessor in office remarked, in the opening of his address, that two courses are open to the retiring president of this As ociation in preparing the annual presidential discourse,—he may either take up some topic relating to his own specialty, or he may deal with various or general matters relating to science and its progress. A geologist, however, is not necessarily tied up to one or the other alternative. His subject covers the whole history of the earth in time. At the beginning it allies itself with astronomy and physics and celestial chemistry. At the end it runs into human history, and is mixed up with archæology and anthropology. Throughout its whole course it has to deal with questions of meteorology, geography, and biology. In short, there is no department of physical or biological science with which geology is not allied, or at least on which the geologist may not presume to trespass. When, therefore, I announce as my subject on the present occasion some of the unsolved problems of this universal science, you need not be surprised if I should be somewhat discursive.
"Acadian Geology," third edition, supplement, p. 68.
"Footprints and Impressions on Carboniferous Rocks," Amer. Journ, Sc., 1873.
"Apropos des Algues Fosslles," Paris, 1883.
Science, July 1, 1883