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608 of Eastern Virginia;" and "On the Physical Structure of the Appalachian Chain," etc. In the first of these papers Prof. Rogers showed that the formation in question, instead of being of an age anterior to the Carboniferous, as had been maintained by Maclure and R. C. Taylor, was of Mesozoic time. In the second paper he described the position of more than fifty thermal springs in the Appalachian belt, occurring in an area of about 15,000 square miles, deducing the law that these thermal springs issue from anticlinal axes and faults, or from points very near such lines, and, in connection with their chemistry, proving the important fact of the great preponderance of nitrogen in the free and combined gases of these springs. The observations on subterranean temperature recorded in the third paper were the first published confirmation, as regards the United States, of the law of augmenting temperature beneath the surface of the earth, although similar observations had been made by Humboldt in Mexico. The memoir on the physical structure of the Appalachian chain, etc., was the joint work of Profs. W. B. and H. D. Rogers, founded on their explorations of this belt in Pennsylvania and Virginia, and its prolongation toward the southwest and northeast. The novelty and importance of its generalizations were at once recognized in Europe as well as at home, and gave the authors, "the Gebrüder Rogers," a prominent place among contemporary geologists; and, so far as the development of the physical structure of the Appalachians is concerned, this memoir is still regarded as of classical value.

Prof. Rogers was chairman of the Association in 1845, and again two years later, when it was expanded into the "American Association for the Advancement of Science," at the first meeting of which he presided until it was fully organized.

In connection with his brother, Robert E. Rogers, now become his colleague as Professor of Chemistry and Materia Medica in the university, he published a number of important chemical contributions, relating chiefly to new or improved methods in chemical analysis and research, in Silliman's Journal, between 1840 and 1850. Among these were papers "On a New Process for obtaining Pure Chlorine;" "A New Process for obtaining Formic Acid, Aldehyde, etc.;" "On the Oxidation of the Diamond in the Liquid Way;” “On New Instruments and Processes for the Analysis of the Carbonates;" "On the Absorption of Carbonic Acid by Liquids," an extended investigation; and "On the Decomposition of Rocks by Carbonated and Meteoric Waters," a paper of much interest in its geological bearings.

In the volume of the "Transactions of the British Association" for 1849, Prof. Rogers called attention to the existence of true coal-measures below the horizon of the Carboniferous limestone in the Appalachian belt as discovered by him in the Virginia survey, and referred to in his annual reports.