Telegrams from educators and scholars mark the third anniversary of the Johns Hopkins Science Review. Dr. Abel Wolman summarizes the history of methods of acquiring pure water and the science of sanitary engineering. Chlorine was discovered to be a reliable and practical chemical to use to kill water-borne bacteria. Dr. Wolman also shows a film of microscopic organisms and silt in water and discusses the decline of typhoid fever. Dr. Wolman and his colleagues use both animated films and models of a water filtration plant and a sewage treatment plant to explain the water purification processes.