Dr. Ellsworth Huntington, who died recently at the age of seventy-one, was well known for his views on the dominant effect of climate on human affairs. As a student of geography under Prof. W. M. Davis, he spent the years from 1900 to 1906 in the exploration of Asia Minor and Central Asia, his first paper being an account of the Upper Euphrates published in 1902. In Central Asia he was struck by the evidence that large populations formerly inhabited regions now arid and deserted, and from these and other historical studies, including the changes of level of the Caspian Sea, he developed the theory that during the past few thousand years there have been great oscillations of climate. These researches were published in “The Pulse of Asia” in 1907 and aroused much controversy among geographers. In the following years he extended his studies of climatic change to Palestine and North America, and he was one of the pioneers in the measurement of tree-rings as climatic indicators. These researches led him to the view that the ideal climate for human vigour is one of moderate but rapidly fluctuating temperatures, which is best, developed in the storm-belts of temperate latitudes; and in “Civilization and Climate” (1915) he compared estimates of the level of existing civilizations in different countries, obtained in various ways, with their level of climatic energy, finding remarkably close agreement. In the same book he extended his studies of the effect of climatic changes on the history of ancient civilizations, including a new version of the decline and fall of the Roman Empire.