Earth, early history of, 3, 4; dimensions of, relative to surface
features, 117.
Earth's age determined by thickness of sediments, 5; determined
by mass of the sediments, 7; determined by sodium in the ocean,
12; determined by radioactive transformations, 19; significance
of, 2.
Earthquakes associated with geosynclincs, 142.
Efficiency, tendency to maximum, in organisms, 113, 114.
Elements, probable wide diffusion of rare, 230; rarity of
radioactive, 241.
Elster and Geitel, photo-electric activity and absorption, 207;
photo-electric properties of gelatin, 212; Emanation of radium,
therapeutic use of, 256-259; advantages of, in medicine, 256;
volume of, 257; how obtained, 257; use of, in needles, 258.
Equilibrium amount, meaning of, 254, 255.
Evolution and acceleration of activity, 79; of the universe not
eternal a pane ante, 298.