EDITED BYJ. ARTHUR THOMSONREGIUS PROFESSOR OF NATURAL HISTORY IN THEUNIVERSITY OF ABERDEENIN FOUR VOLUMESCopyright, 1922byG. P. Putnam's SonsCONTENTSINTRODUCTION 3I. THE ROMANCE OF THE HEAVENS 7 The scale of the universe--The solar system--Regions of the sun--The surface of the sun--Measuring the speed of light--Is the sun dying?--The planets--Venus--Is there life on Mars?--Jupiter and Saturn--The moon--The mountains of the moon--Meteors and comets--Millions of meteorites--A great comet--The stellar universe--The evolution of stars--The age of stars--The nebular theory--Spiral nebulæ--The birth and death of stars--The shape of our universe--Astronomical instruments.II. THE STORY OF EVOLUTION 53 The beginning of the earth--Making a home for life--The first living creatures--The first plants--The first animals--Beginnings of bodies--Evolution of sex--Beginning of natural death--Procession of life through the ages--Evolution of land animals--The flying dragons--The first known bird--Evidences of evolution--Factors in evolution.III. ADAPTATIONS TO ENVIRONMENT 113 The shore of the sea--The open sea--The deep sea--The fresh waters--The dry land--The air.IV. THE STRUGGLE FOR EXISTENCE 135 Animal and bird mimicry and disguise--Other kinds of elusiveness.V. THE ASCENT OF MAN 153 Anatomical proof of man's relationship with a Simian stock--Physiological proof--Embryological proof--Man's pedigree--Man's arboreal apprenticeship--Tentative men--Primitive men--Races of mankind--Steps in human evolution--Factors in human progress.VI. EVOLUTION GOING ON 183 Evolutionary prospect for man--The fountain of change; variability--Evolution of plants--Romance of wheat--Changes in animal life--Story of the salmon--Forming new habits--Experiments in locomotion; new devices.VII. THE DAWN OF MIND 205 A caution in regard to instinct--A useful law--Senses of fishes--The mind of a minnow--The mind and senses of amphibians--The reptilian mind--Mind in birds--Intelligence co-operating with instinct--The mind of the mammal--Instinctive aptitudes--Power of association--Why is there not more intelligence?--The mind of monkeys--Activity for activity's sake--Imitation--The mind of man--Body and mind.VIII. FOUNDATIONS OF THE UNIVERSE 243 The world of atoms--The energy of atoms--The discovery of X-rays--The discovery of radium--The discovery of the electron--The electron theory--The structure of the atom--The new view of matter--Other new views--The nature of electricity--Electric current--The dynamo--Magnetism--Ether and waves--Light--What the blue "sky" means--Light without heat--Forms of energy--What heat is--Substitutes for coal--Dissipation of energy--What a uniform temperature would mean--Matter, ether, and Einstein--The tides--Origin of the moon--The earth slowing down--The day becoming longer.