As the sections of Hydrology and Meteorology in the Geophysical Union are organized and the respective fields of activity are defined, the interrelation of interests of the two sections is so obvious as to appear to render discussion unnecessary. Their fields added to that of oceanography cover that never‐ending cycle of motion of water wherein it condenses in clouds, is precipitated as rain or snow, flows over and through the Earth's crust, accumulates largely in oceans, is taken into the air again by evaporation and transpiration, and is again condensed into clouds and precipitated. The Section of Hydrology works within that portion of this cycle that is represented approximately by the passage of water over and through the Earth's crust, the Section of Meteorology works within that portion represented approximately by the passage of water through the atmosphere, and the Section of Oceanography works within that portion represented by the oceans. Each field of activity begins, therefore, where another ends, and the work of one section is related to and must be consistent with the work of each of the others. The obvious points of contact between the sections of Hydrology and Meteorology are in those phases that relate to the transfer of water from the atmosphere to the Earth's crust (precipitation) and to the reverse action of transfer from the Earth's crust to the atmosphere (evaporation