In the course of a decade's work on the mountains of East Africa, I met some of the most wonderful people on Earth. It is impossible to record all those who have helped me in this study in one way or other. Glacier research in East Africa has some history. Nearly half a century ago, Carl Troll completed the first detailed mapping of Lewis Glacier. I had the good fortune of exchanging ideas with him at his home in Bonn in 1974, shortly before his death. Paul C. Spink, Ulceby, North lincolnshire, England, shared with me his photographs and observations on Kilimanjaro and Mount Kenya in the 1940s. When I joined the University of Nairobi in 1973, several members of the 1957-58 IGY Mc)Unt Kenya: Expedition were still there. I received generous advice and help from Igor Loupekine, John Loxton, but especially from Robert A. Caukwell and Frank Charnley. Their continuous coopera- tion was a great encouragement over the years. Heinz Loeffler, University of Vienna, informed me about the depth of Lewis Tarn. Helmut Heuberger, University of Munich, provided me data on his measurements of glacier terminus positions. Peter Gollmer of Geosurveys and Alan Root, Nairobi, gave me aerial photographs of Kibo f om the early 1970s. I acknowledge support from various other colleagues at the University of Nairobi: Raouf Rostom of the Department of Surveying and Photogrammetry; Neville Skinner of the Department of Physics; G. C. Asnani, John Ng'anga, J. K.