Page:Popular Science Monthly Volume 52.djvu/270

256 contributed valuable papers, one of them embodying the conclusion that the coal fields under the Secondary rocks of the south and southeast of England might extend from Somersetshire to the neighborhood of Folkestone, which has been confirmed by borings at Dover.

Dr. Prestwich retired from business in 1872, and in 1874 became professor of geology at Oxford. He continued his researches with his accustomed activity, and enriched the literature of geology from year to year with numerous valuable and original contributions, in the form of papers and addresses to learned societies, in connection with which his name constantly appears, and of books which are indispensable to the thorough student of the science.

Dr. Prestwich's annual address as president of the Geological Society in 1872 gives an admirable, statement of the purposes of geological research with reference to the advent of man, and further on of its practical applications to the questions of water supply and coal. Among the theoretical problems that were then occupying the attention of geologists of all nations, the speaker said, were the phenomena connected with the prevalence of great and exceptional cold immediately preceding our time, the first dim appearance of man, his association with a race of great extinct mammalia belonging to a cold climate, the persistent zoölogical characteristics of man as contrasted with the variable animal types presented in geological time, the search for connecting links, and the measure of man's antiquity. Allied to these were the great questions relating to the forms of the continents—the elevation of the land, the origin of valleys and plains, and all that prepared the globe for the advent of man. Further, geology dealt with the requirements of civilized man, "showing him the best way of providing for many of his wants, and guiding him in the search for much that is necessary for his welfare. The questions of water supply, of building materials, of metalliferous veins, of iron and coal supply, and of surface soils all come under this head and constitute a scarcely less important although a more special branch of our science than the paleontological questions connected with the life of past periods, or than the great theoretical problems relating to physical and cosmical phenomena." Proceeding to consider the geological questions connected with water supply, the author suggested that the site of a spring or the presence of a stream determined probably the first settlements of savage man; and his civilized descendants, until the last few years, equally depended upon like conditions. These conditions were connected with the rainfall and with the distribution of the permeable and impermeable strata forming the surface of the country. Under ordinary circumstances few large towns had arisen except where a localized water supply was easily accessible, where