INDEX 
Skull, Piltdown, 49-51, 136-141 
Rhodesian, 160-162 
Skulls, as drinking cups, 225 
Krapina, 108 ~ 
prehistoric, 46 
Slavery, origin of, 254 
Snakes, ancient, 17 
Social system of ancient China, 
320 
of Aztecs, 338 
of Neanderthalers, 196 
Solar system, origin of, 8 
Solutrean epoch, 43, 52, 72, 75, 
76, 206-212 
Solutré, France, 43 
prehistoric site, 53 
“Son of Heaven,” 321 
“Sorcerer, The,” of Trois Fréres, 
B90) 904 
Sound symbols, 290, 291 
South America, ancient civiliza- 
tion of, 340-349 
Space, extent of, 4 
Spain, ancient, 227-232 
Spear-thrower, 216 
Species, origin of, 20 
number of, 20 
Spectrum of star, 7 
Spy, prehistoric site, 96 
skeletons, 101 
Squirrels, ancient, 18 
Star, nearest, 1, 8 
Stars, 1, 2, 4, 6-8 
State socialism of Incas, 341, 342 
Statuettes of women, 205, 209 
Steel Age, 41 
Steppes, 61 
Stone as building material, 283, 
284, 295, 298, 331, 332, 343, 
344 
Stonehenge, circle at, 283 
Stones, groups of upright, 283 
String, uses of, 175, 345 
Sumerians, 302-305 
Sun, the, 1,304 
Sunken rivers, 63 
Syllabary, 291 
T 
Tardenoisian culture, 232 
Tasmanians, culture of, 184 
Teeth of man, 48 
Temple-pyramids of Aztecs, 340 
Temples of Crete, 311 
of Egypt, 299 
Incas, 346 
India, 313 
Mayas, 331, 332 
Tenochtitlan, 338, 340 
Thigh bone of man, 49, 89 
“Three-man spade” of Korea, 260 
Time, calculation of geologic, 3, 
10, 69, 70 
Tin, in Bronze Age, 268 
Toltec civilization, 337 
Tools, first use of, 171 
Transportation, methods of, 275- 
278, 344-345 
Trees, fossil, 15 
Triassic period, 16 
Trilobites, 13, 14 
Trinil, Pithecanthropus, found at, 
146 
Tuareg race, 228 
Tundras, 60 
Turkey, domestication of, 339 
Turtles, ancient, 17 
U 
Ultra-violet rays, 5 
Universe, chemical composition 
of, 5 
structure of, 4 
Universes, number of island, 2 
Vv 
Variation, mechanism of, 24 
Varves, 69 
Vegetation, heroic age of, 12, 14 
[ 374 | 
