Quasi-Euclidean universe, 136
Quasi-spherical universe, 136
Radiation, 55
Radioactive substances, 59
Reference-body, 5, 7, 8–11, 22, 28, 31, 32, 44, 70
——— rotating, 94
——— mollusk, 118-120
Relative position, 3
——— velocity, 141
Rest, 17
Riemann, 102, 128, 132
Rotation, 95, 147
Schwarzschild, 158
Seconds-clock, 44
Seeliger, 125, 127
Simultaneity, 26, 29-32, 96
——— relativity of, 31
Size-relations, 107
Solar eclipse, 89, 153, 155
Space, 9, 62, 65, 125
——— conception of, 24
Space co-ordinates, 66, 96, 118
Space-interval, 36, 67
——— point, 118
Space, two-dimensional, 128
——— three-dimensional, 147
Special theory of Relativity, 1–68, 24
Spherical surface, 129
——— space, 132, 133
St. John, 159
Stellar universe, 126
——— photographs, 153
Straight line, 1–3, 9, 10, 97, 105, 129
System of co-ordinates, 5, 10, 11
Terrestrial space, 18
Theory, 148
——— truth of, 149
Three-dimensional, 65
Time, conception of, 24, 61, 125
——— co-ordinate, 66, 118
——— in Physics, 26, 117, 146
——— of an event, 28, 32
——— interval, 36, 67
Trajectory, 10
“Truth,” 2
Uniform translation, 14, 69
Universe (World), structure of, 128, 135
——— circumference of, 131
Universe, elliptical, 133, 136
——— Euclidean, 130, 132
——— space expanse (radius) of, 137
——— spherical, 132, 136
Value of 7, 97, 130
Velocity of light, 11, 21, 22, 89, 143
Venus, 152
Weight (heaviness), 77
World, 65, 66, 130, 147
World-point, 147
——— -radius, 133
——— -sphere, 130, 131
Zeeman, 48
