A joint meeting of the Sections of Volcanology and Geophysical Chemistry of the American Geophysical Union was held at the Carnegie Institution of Washington on April 18, 1923, and was devoted to a symposium and discussion on the temperatures of hot springs and the sources of their heat and water supply. Ten papers were presented.The temperatures of hot springs range all the way from those found in warm springs in the mountains of Virginia, some of which are only slightly above the annual mean temperature, up through boiling springs and mud pots such as are found in our western volcanic regions, to fumarole temperatures of about 650°C, the highest temperature found in the Valley of Ten Thousand Smokes, Alaska, reported on by E. G. Zies in his paper on “Hot Springs and Fumaroles of the Katmai Region.”