Nebular Hypothesis, one of the theories as to how the world was made, 4; how it differs from the latest theory, 6; the Bible story compared with both theories, 17 Neptune (planet), 6 New England, how the Old Men of the Mountain plowed its farms away, 31; and then made up for it by putting in New England's waterfalls, 32 Newton, his connection with the theory of the origin of worlds, 4 New York City, what one of its big rocks tells about marble making, 97; what its harbor owes to the engineering of the sea, 221, 222; the perched boulder in Bronx Park and its autograph, 250 Niagara Falls, its thousand-year clock and what it tells about the Ice Age, 35; how the Old Men of the Mountain set the falls up in business, 36 Nitrogen, how it helped to make fresh air for the new-born world, 16 Norway, interpretation of the handwriting on the walls of its fiords, 254 Ogden Canyon, curious example of a rock fold, 238 Ohio River, how the Old Men of the Mountain helped it by turning some rivers around, 31 Omar Khayyam, answer of Science to the universal riddle that puzzled him, 261 Origin of Species. (See Evolution.) Oxygen, its use in making the world's air, 16; how the sea feeds oxygen to the corals, 225 Pack Rat, his remarkable fortress in the desert, 187 Paleontologists, the wizards of queer anatomies and the strange forms they conjure up from the fragments of old bones, 266 Palestine. (See Dead Sea.) Palisades, how they were made in the "Middle Ages," 241 Pebbles, how they tell of old sea beaches on inland mountain and hill, 14; their enormous age, 18; dramatic stories the pebble scratches tell, 26; how the Old Men of the Mountain used pebbles in turning New England rivers around, 31; how pebbles helped deepen the basins of the Great Lakes, 34; how they still help run the thousand-year clock at Niagara Falls, 35; how they help the glaciers talk, 56; why the pebbles of Glacier Land can't walk as the big stones do, 62; how the river pebbles act as bankers for the farmers and the sea, 80; how the pebbles helped dig the Grand Canyon, 82; how they tell about doings in the Fairyland of Change, 97; how a pebble may, in its time, play many parts, 99; how they help unravel the secrets of the hills, 119; how they help dying rivers multiply by two, 167; how they report the fact that the storms on the Sea of Galilee are particularly severe, 203; their fixed place in the rock-making system of the sea, 227; how they tell of rough experiences in river travel, 250; and of high winds at sea, desert sandstorms, rides on glaciers, and in what compartments they travel, 251 Peninsulas, how the drowning of rivers helps to make them, 212 Pennsylvania, autographs left by ancient reptiles in the sandstone under the coal seams, 245