The hydrologists who are concerned with the study of the water that occurs below the land‐surface feel strongly the need of better agreement among the different countries as to the fundamental concepts of this branch of hydrology and as to technical terms to designate these concepts. For this reason, the question as to the definitions of different kinds of subterranean water was selected as one of the three questions for discussion by the International Commission on Subterranean Water at the meeting in Edinburgh in 1936 and again (as Question No. 2) at the meeting that is to be held in Washington in September, 1939.

The purpose of the International meetings is not only to discuss subjects of mutual interest but also, so far as practicable, to make official decisions. Obviously, decisions on scientific questions should be made only after mature consideration and only on questions as to which there is general agreement. The reports that have been prepared in different countries on the question under consideration and the correspondence and oral discussion appear to show that the way is open for International agreement on some of the basic concepts. A comprehensive paper on the question was prepared for the Edinburgh meeting by Dr. Vasillevskij, of Russia (Internat, Ass. Sci. Hyd., Bull. 22, 1936). Dr. Yasilievskij, in a letter dated January 12, 1939, urges that a beginning be made at the Washington Assembly to adopt new terms on the basis of Latin and Greek roots, these terms to have strict meanings for all countries. The following are tentative suggestions for such a beginning, based especially on information from France, Germany, Great Britain, Holland, Japan, Russia, and the United States.