Science: The Electric Earth

Washington's Carnegie Institution, which does "significant research toward philosophical goals," has been looking at the earth philosophically for several years. Last week its annual yearbook reported progress on some significant problems.

Earth Charge. Since 1917 scientists have known that the earth's surface is charged with negative electricity, but no one knew for sure what keeps it charged. In areas of fair weather, an electric current flows between the earth and the air in a direction which would tend to dissipate the charge. It is not much of a current: only about 1,500 amperes,...