Oreography (ō-rē-ŏg´rȧ-fy̆).—The science of mountains; orography.
Palæotherium (pā-lē-ō-thē´ri-um).—A tapir-like mammal, having canine teeth, known only by fossil remains found in Tertiary rocks.
Pampero (pȧm-pâ´rô).—A violent wind from the west or southwest, which sweeps over the pampas of South America and the adjacent seas, often doing great damage.
Parhelion (pär-hēl´yŭn or hē´lĭ-ŏn).—A mock sun appearing in the form of a bright light, sometimes near the sun, and tinged with colors like the rainbow, and sometimes opposite to the sun. The latter is usually called an anthelion. Often several mock suns appear at the same time.
Petrology (pē-trŏl´ô-jy̆).—The science which is concerned with the mineralogical and chemical composition of rocks, and with their classification; lithology.
Physiography (fiz-e-ŏg´rȧ-fy̆).—The science which treats of the earth’s exterior physical features, climate, life, etc., and of the physical movements or changes on the earth’s surface, as the currents of the atmosphere and ocean, the secular variations in heat, moisture, magnetism, etc.; physical geography.
Plesiosaurus (plē-zi-ō-saw´rus).—An oolithic reptile with crocodile-like head, known by fossil remains, chiefly vertebræ, found in lias and oolitic rocks, named from its fossil remains being found near those of the ichthyosaurus.
Pneumatics (nû-măt´ĭks).—That branch of science which treats of the mechanical properties of air and other elastic fluids, as of their weight, pressure, elasticity, etc.
Pterodactyl (ter-ō-dak´tīl).—Winged lizard: extinct reptile; fossil remains found in Kentish chalk.
Pyroscope (pĭr´ô-skōp).—An instrument for measuring the intensity of heat radiating from a fire, or the cooling influence of bodies. It is a differential thermometer, having one bulb coated with gold or silver leaf.