Mr. I. C. Russell read a paper on "The geology of the Mount St. Elias region, Alaska." The paper was discussed by Messrs Gilbert (who had resigned the chair to Vice-President Hayden), Dall, Johnson, and Russell. _Incorporated in the memoir forming pp. 53-204, pls. 2-20, of this volume_. {viii} _March 31, 1891. Special meeting_. Meeting held in the Law Lecture Room of Columbian University. Vice-President Ogden in the chair. Attendance, 300. Mr. Sergius Stepniak delivered an address on "The Russian peasantry." _April 3, 1891. 51st meeting_. Meeting held in the Assembly Hall of the Cosmos Club, Vice-President Hayden in the chair. Attendance, 35. A paper on "The Mackenzie river and Colinson," by Vice-President Greely, was read by title in the absence of the author. Ensign J. A. Hoogewerff, U. S. N., presented an account of the "Magnetic work of the United States Naval Observatory." The paper was discussed by Messrs Baker, Abbe, Ogden, Hayden, and Hoogewerff. Mr. F. H. Bigelow presented a paper on "Auroral streamers." Mr. Cleveland Abbe made some remarks on "Theories of magnetic phenomena." _April 11, 1891. Special meeting_. Meeting held in the Lecture Hall of the National Museum. President Hubbard in the chair. Attendance, 750. Major J. W. Powell delivered an address on "The Grand cañon of Colorado river." _April 17, 1891. 52d meeting_. Meeting held in Lincoln Hall. President Hubbard in the chair. Attendance, 1,000. Mr. Geo. W. Melville, Engineer-in-Chief, U. S. N., briefly explained the purposes of arctic exploration. Civil Engineer R. E. Peary, U. S. N., addressed the Society on the subject of his proposed northern Greenland expedition of 1891-92. The lecturer exhibited and explained a number of lantern-slide views illustrating arctic scenery and modes of traveling. On the conclusion of the address a United States flag, provided for the purpose by Miss Ulrica Dahlgren, was presented by the President on behalf of the Society to Lieut. Peary, who responded feelingly. {ix} _April 24, 1891. Special meeting_. Meeting held in the Lecture Room of the National Museum. Attendance, 400. Mr. H. M. Wilson, of the United States Geological Survey, delivered an address on the subject "India: Its geography and people." At the close of the lecture Mr. Wilson exhibited and explained a number of lantern-slides made from views taken by him while traveling in India. _May 1, 1891. 53d meeting_. Meeting held in the Lecture Hall of the National Museum. Vice-President Hayden in the chair. Attendance, 600. Mr. Courtenay De Kalb delivered an address on "The great Amazon: Personal investigations on the Great River and in its upper valley." At the close of the lecture Mr. De Kalb exhibited a number of lantern-slide views, which he described. _May 15, 1891. 54th meeting_. Meeting held in the Assembly Hall of the Cosmos Club. Vice-President Hayden in the chair. Attendance, 25.