DURING the last few years we have lost three of our leading seismologists. G. W. Walker died in 1921, C. G. Knott in 1922, and, late in 1923, Fusakichi Omori, the well-known professor of seismology in the Imperial University of Tokyo and president of the Japanese Imperial Earthquake Investigation Committee. At an early age he was fortunate in coming under the inspiring influence of John Milne and, encouraged by him, took up the study of the aftershocks of earthquakes. For a time he worked on other subjects with Milne, who left Japan in 1895, and with S. Sekiya, the first professor of seismology in the Imperial University. On the death of the latter in 1896, Omori succeeded to his chair, and about the same time became secretary of the Imperial Earthquake Investigation Committee. In this position he attained great influence. He became the natural leader in all Japanese investigations on volcanoes and earthquakes, and kept in close and friendly touch with the heads of other scientific departments. At the time of the great earthquake of September i he was absent from Japan, on a voyage apparently in search of health. He returned to the ruined city and died there on November 8.