The style employed in the Index is a standard for such material. Volume numbers are represented by the Roman numerals, i, ii, iii, iv, v, vi, vii, viii, ix, x, xi, xii, xiii, xiv, xv, xvi. Pages are indicated by figures. All topics and subtopics are arranged alphabetically. When you read or study the Popular Science Library, keep the Index volume at hand whenever it is convenient. It will add greatly to your interest and give you a depth of insight into these matters if you can compare one author's opinions and descriptions with those of another. If you are consulting the Library as a reference collection for information on particular topics, the Index will give you volume and page for every bit of text on the subject you are considering. The Popular Science Library is unique in the number and standing of its authors and in the care that has been taken to make it the easiest as well as the most engrossing of all scientific collections for the reader or student to use. CONTENTS PAGE HOW TO USE THE POPULAR SCIENCE LIBRARY. BY GARRETT P. SERVISS 9 HISTORY OF SCIENCE 39-198 CHAPTER I. HISTORY OF SCIENCE 39 II. PRIMITIVE MAN AND EARLY CIVILIZATIONS 46 III. PRE-BABYLONIAN SCIENCE 56 IV. EGYPTIAN SCIENCE 64 V. FOUNDING OF SYSTEMATIC SCIENCE IN GREECE 76 VI. GOLDEN AGE OF GREEK SCIENCES 86 VII. THE ROMAN AND MIDDLE AGES 97 VIII. SCIENCE IN THE SEVENTEENTH CENTURY 106 IX. PRELUDE TO MODERN SCIENCE--THE EIGHTEENTH CENTURY 117 X. PHYSICAL SCIENCES IN THE NINETEENTH CENTURY 129 XI. THE NATURAL SCIENCES 139 XII. ORGANIC EVOLUTION, VARIATION, AND HEREDITY 149 XIII. CHEMICAL AND BOTANICAL THEORIES 159 XIV. GEOLOGY, METALLURGY, AND METEOROLOGY 168 XV. MEDICINE AND PHARMACY 178 XVI. ELECTRICITY AND RADIOACTIVITIES 188 XVII. SCIENCE IN THE TWENTIETH CENTURY 195 GENERAL INDEX 199-384 LIST OF ILLUSTRATIONS THE MAJESTIC, LARGEST STEAMSHIP IN THE WORLD _Frontispiece_ FACING PAGE EOHIPPUS--FROM WHICH THE MODERN HORSE DEVELOPED 16 ORNITHOLESTES--A PREHISTORIC ANIMAL OF AMERICA 17 HUNTSMAN, HORSE, AND HUNTING DOG OF LONG AGO--FROM AN ANCIENT CRETAN FRESCO 17 PREHISTORIC PAINTINGS--AN EXHIBITION OF COPIES FROM THE CAVERN AT ALTAMIRA, SPAIN 24 SABER-TOOTHED TIGER THAT ONCE ROAMED OVER NORTH AMERICA 25 GUTENBERG'S PRINTING PRESSES--MODELS ON EXHIBITION 32 BENJAMIN FRANKLIN'S PRINTING PRESS 33 MODEL OF THE "SANTA MARIA," THE FLAGSHIP OF COLUMBUS 48 CURTISS NAVY RACER, THE AIRPLANE THAT WON THE PULITZER RACE OF 1921 49 U. S. ARMY DIRIGIBLE ON A TRANSCONTINENTAL FLIGHT 49 ELECTRIC MOTOR OF 1834 64 TURNING LATHE OF 1843 64