It is unanimously agreed, I think, that of the water which falls upon the Earth's surface, a part runs off toward the sea, a part is at least temporarily detained, a part of it evaporates, and a part sinks beneath the ground‐surface. But among students of that water which sinks beneath the Earth's surface, complete agreement as to the course it then takes has not always prevailed. Ground‐water hydrologists have assumed that water can and does reach the water‐table by descending through a great thickness of subsoil in the semi‐arid upland divides of the Great Plains. But many students of soil‐moisture and its use by vegetation in the Great Plains have concluded from their soil‐moisture sampling that water does not descend to the water‐table where the depth to the water‐table is great. Thus Cole and Mathews state in Technical Bulletin 637 of the United States Department of Agriculture, page 69, that “It can be safely said, however, that on the short‐grass land of the Great Plains there is no penetration of upland surface‐water to the water‐table.”