This report is the annual accounting by the Quartermaster Corps of its stewardship of applied environmental research within the Department of the Army. This stewardship is exercised by the Quartermaster Corps under its primary cognizance for the field as defined and assigned by the General Staff, U.S. Army (Appendix 1). Applied environmental research is a form of military geography--the study of the environment pointed toward the solution of logistical problems. A searching examination of the environment is necessary for adequate designing, realistic testing, development of sound field doctrine, and successful action of men in the field. The environment must be taken into consideration by scientists and engineers in launching the most modern rocket in Florida or California, as well as by small groups of soldiers conducting guerrilla warfare in dim tropical forests. Success of the launching or of the guerrilla action depends in part upon the degree to which environmental factors have been considered in prior development of materiel and doctrine. The environmental research and development program of the Army is carried out by all technical services and USCONARC, individually and through cooperative effort. Coordination is achieved through meetings of the Army Committee on Environment on which all technical services are represented; the Army Scientific Advisory Panel; and the Army Research Office, Office of the Chief of Staff. In addition, there is frequent exchange of ideas through conferences and correspondence at all levels. Two major aspects of Army Environmental Research and Development can be distinguished: The first is devoted to discovering the nature of the environment; The second is devoted to developing materiel that will function properly under all environmental stresses in protecting soldiers and helping them achieve success in battle. Obviously these two aspects of study are mutually dependent. There is not always a sharp line of demarcation between them, though most of the research in the first category is done by earth scientists (Geographers, Climatologists, Meteorologists, Soil Scientists, Ecologists, etc.), while that of the second is more likely to be done by engineers. All the technical services are committed to development and testing of materiel and its use by soldiers under all environments; Research on the environment per se, on the other hand, is carried out by the Quartermaster Corps under its primary cognizance, though major contributions in certain aspects are made by other technical services. In carrying out their research responsibilities, Army scientists draw upon all available sources of information and must be aware of new and important developments in their fields in this country and throughout the world. Professional journals are a major source of information; in addition, contacts are maintained with other scientists through attendance at scientific meetings, exchange agreements, correspondence, and visits to scientific institutions. For example, during the past year the International Geographical Congress at Stockholm was attended by a number of earth scientists from the Department of Army. Five Army Geographers and Climatologists presented papers at the Congress and was re-elected to serve as Chairman of one Worldwide Scientific Commissions during the next four years. By maintaining their status as an active part of the scientific community, Army scientists are able to build and maintain a staff of competent personnel, secure the cooperation of outstanding authorities for contract work, keep their own research up-to-date with recent developments, and avoid wasteful duplication of work that has already been elsewhere. The main body of this report gives an account of the principal research efforts of the past year. Accomplishments during this time give promise of valuable additions in subsequent years. Comprehensive Climactic Atlases, recently published, of temperature frequencies in the colder portions of the northern hemisphere will be followed by others of tropical and desert regions; new techniques of terrain analysis will be given further applications; on-the-spot investigations of difficult environments will be extended to other types of areas; and from many other angles, some not yet conceived, the unlimited problems of the environment will be analyzed, brought to focus upon Army problems, digested into usable documents and manuals, and incorporated into the design and use of Army materiel.