Chapter 2

PHOTOGRAPH SHOWING A NARROW PASSAGE IN THE CAVERN OF FONT-DE-GAUME ON THE BEUNE 179 Reproduced by permission from Osborn's _Men of the Old Stone Age_.

A MAMMOTH DRAWN ON THE WALL OF THE FONT-DE-GAUME CAVERN 179

A GRAZING BISON, DELICATELY AND CAREFULLY DRAWN, ENGRAVED ON A WALL OF THE ALTAMIRA CAVE, NORTHERN SPAIN 179

PHOTOGRAPH OF A MEDIAN SECTION THROUGH THE SHELL OF THE PEARLY NAUTILUS 186

PHOTOGRAPH OF THE ENTIRE SHELL OF THE PEARLY NAUTILUS 186

NAUTILUS 186

SHOEBILL 187 Photo: W. S. Berridge.

THE WALKING-FISH OR MUD-SKIPPER (_Periophthalmus_), COMMON AT THE MOUTHS OF RIVERS IN TROPICAL AFRICA, ASIA, AND NORTH-WEST AUSTRALIA 190

THE AUSTRALIAN MORE-PORK OR PODARGUS 190 Photo: _The Times_.

PELICAN'S BILL, ADAPTED FOR CATCHING AND STORING FISHES 191

SPOONBILL'S BILL, ADAPTED FOR SIFTING THE MUD AND CATCHING THE SMALL ANIMALS, E.G. FISHES, CRUSTACEANS, INSECT LARVÆ, WHICH LIVE THERE 191

AVOCET'S BILL, ADAPTED FOR A CURIOUS SIDEWAYS SCOOPING IN THE SHORE-POOLS AND CATCHING SMALL ANIMALS 191

HORNBILL'S BILL, ADAPTED FOR EXCAVATING A NEST IN A TREE, AND ALSO FOR SEIZING AND BREAKING DIVERSE FORMS OF FOOD, FROM MAMMALS TO TORTOISES, FROM ROOTS TO FRUITS 191

FALCON'S BILL, ADAPTED FOR SEIZING, KILLING, AND TEARING SMALL MAMMALS AND BIRDS 191

PUFFIN'S BILL, ADAPTED FOR CATCHING SMALL FISHES NEAR THE SURFACE OF THE SEA, AND FOR HOLDING THEM WHEN CAUGHT AND CARRYING THEM TO THE NEST 191

LIFE-HISTORY OF A FROG 192

HIND-LEG OF WHIRLIGIG BEETLE WHICH HAS BECOME BEAUTIFULLY MODIFIED FOR AQUATIC LOCOMOTION 192 Photo: J. J. Ward, F.E.S.

THE BIG ROBBER-CRAB (_Birgus Latro_), THAT CLIMBS THE COCONUT PALM AND BREAKS OFF THE NUTS 193

EARLY LIFE-HISTORY OF THE SALMON 196

THE SALMON LEAPING AT THE FALL IS A MOST FASCINATING SPECTACLE 197

DIAGRAM OF THE LIFE-HISTORY OF THE COMMON EEL (_Anguilla Vulgaris_) 200

CASSOWARY 201 Photo: Gambier Bolton.

THE KIWI, ANOTHER FLIGHTLESS BIRD, OF REMARKABLE APPEARANCE, HABITS, AND STRUCTURE 201 Photo: Gambier Bolton.

THE AUSTRALIAN FRILLED LIZARD, WHICH IS AT PRESENT TRYING TO BECOME A BIPED 202

A CARPET OF GOSSAMER 202

THE WATER SPIDER 203

JACKDAW BALANCING ON A GATEPOST 208 Photo: O. J. Wilkinson.

TWO OPOSSUMS FEIGNING DEATH 208 From Ingersoll's _The Wit of the Wild_.

MALE OF THREE-SPINED STICKLEBACK, MAKING A NEST OF WATER-WEED, GLUED TOGETHER BY VISCID THREADS SECRETED FROM THE KIDNEYS AT THE BREEDING SEASON 209

A FEMALE STICKLEBACK ENTERS THE NEST WHICH THE MALE HAS MADE, LAYS THE EGGS INSIDE, AND THEN DEPARTS 209

HOMING PIGEON 212 Photo: Imperial War Museum.

CARRIER PIGEON 212 Photo: Imperial War Museum.

YELLOW-CROWNED PENGUIN 213 Photo: James's Press Agency.

PENGUINS ARE "A PECULIAR PEOPLE" 213 Photo: Cagcombe & Co.

HARPY-EAGLE 216 Photo: W. S. Berridge.

THE DINGO OR WILD DOG OF AUSTRALIA, PERHAPS AN INDIGENOUS WILD SPECIES, PERHAPS A DOMESTICATED DOG THAT HAS GONE WILD OR FERAL 216 Photo: W. S. Berridge, F.Z.S.

WOODPECKER HAMMERING AT A COTTON-REEL, ATTACHED TO A TREE 217

THE BEAVER 220

THE THRUSH AT ITS ANVIL 221 Photo: F. R. Hinkins & Son.

ALSATIAN WOLF-DOG 226 Photo: Lafayette.

THE POLAR BEAR OF THE FAR NORTH 227 Photo: W. S. Berridge.

AN ALLIGATOR "YAWNING" IN EXPECTATION OF FOOD 227 From the Smithsonian Report, 1914.

BABY ORANG 232 Photo: W. P. Dando.

ORANG-UTAN 232 Photo: Gambier Bolton.

CHIMPANZEE 233 Photo: James's Press Agency.

BABY ORANG-UTAN 233 Photo: James's Press Agency.

ORANG-UTAN 233 Photo: James's Press Agency.

BABY CHIMPANZEES 233 Photo: James's Press Agency.

CHIMPANZEE 238 Photo: W. P. Dando.

YOUNG CHEETAHS, OR HUNTING LEOPARDS 238 Photo: W. S. Berridge.

COMMON OTTER 239 Photo: C. Reid.

SIR ERNEST RUTHERFORD 246 Photo: Elliott & Fry.

J. CLERK-MAXWELL 246 Photo: Rischgitz Collection.

SIR WILLIAM CROOKES 247 Photo: Ernest H. Mills.

PROFESSOR SIR W. H. BRAGG 247 Photo: Photo Press.

COMPARATIVE SIZES OF MOLECULES 250

INCONCEIVABLE NUMBERS AND INCONCEIVABLY SMALL PARTICLES 250

WHAT IS A MILLION? 250

THE BROWNIAN MOVEMENT 251

A SOAP BUBBLE (_Coloured Illustration_) 252 Reproduced from _The Forces of Nature_ (Messrs. Macmillan).

DETECTING A SMALL QUANTITY OF MATTER 254 From _Scientific Ideas of To-day_.

THIS X-RAY PHOTOGRAPH IS THAT OF A HAND OF A SOLDIER WOUNDED IN THE GREAT WAR 254 Reproduced by permission of X-Rays Ltd.

AN X-RAY PHOTOGRAPH OF A GOLF BALL, REVEALING AN IMPERFECT CORE 254 Photo: National Physical Laboratory.

A WONDERFUL X-RAY PHOTOGRAPH 255 Reproduced by permission of X-Rays Ltd.

ELECTRIC DISCHARGE IN A VACUUM TUBE 258

THE RELATIVE SIZES OF ATOMS AND ELECTRONS 258

ELECTRONS STREAMING FROM THE SUN TO THE EARTH 259

PROFESSOR SIR J. J. THOMSON 262

ELECTRONS PRODUCED BY PASSAGE OF X-RAYS THROUGH AIR 262 From the Smithsonian Report, 1915.

MAGNETIC DEFLECTION OF RADIUM RAYS 263

PROFESSOR R. A. MILLIKAN'S APPARATUS FOR COUNTING ELECTRONS 263 Reproduced by permission of _Scientific American_.

MAKING THE INVISIBLE VISIBLE 266

THE THEORY OF ELECTRONS 267

ARRANGEMENTS OF ATOMS IN A DIAMOND 267

DISINTEGRATION OF ATOMS 270

SILK TASSEL ELECTRIFIED 270 Reproduced by permission from _The Interpretation of Radium_ (John Murray).

SILK TASSEL DISCHARGED BY THE RAYS FROM RADIUM 270

A HUGE ELECTRIC SPARK 271

ELECTRICAL ATTRACTION BETWEEN COMMON OBJECTS 271 From _Scientific Ideas of To-day_.

AN ELECTRIC SPARK 274 Photo: Leadbeater.

AN ETHER DISTURBANCE AROUND AN ELECTRON CURRENT 275 From _Scientific Ideas of To-day_.

LIGHTNING 278 Photo: H. J. Shepstone.

LIGHT WAVES 279

THE MAGNETIC CIRCUIT OF AN ELECTRIC CURRENT 279

THE MAGNET 279

ROTATING DISC OF SIR ISAAC NEWTON FOR MIXING COLOURS (_Coloured Illustration_) 280

WAVE SHAPES 282

THE POWER OF A MAGNET 282

THE SPEED OF LIGHT 283 Photo: The Locomotive Publishing Co., Ltd.

ROTATING DISC OF SIR ISAAC NEWTON FOR MIXING COLOURS 283

NIAGARA FALLS 286

TRANSFORMATION OF ENERGY 287 Photo: Stephen Cribb.

"BOILING" A KETTLE ON ICE 287 Photo: Underwood & Underwood.

THE CAUSE OF TIDES 290

THE AEGIR ON THE TRENT 290 Photo: G. Brocklehurst.

A BIG SPRING TIDE, THE AEGIR ON THE TRENT 291 Photo: G. Brocklehurst.

The Outline of Science

INTRODUCTION

There is abundant evidence of a widened and deepened interest in modern science. How could it be otherwise when we think of the magnitude and the eventfulness of recent advances?

But the interest of the general public would be even greater than it is if the makers of new knowledge were more willing to expound their discoveries in ways that could be "understanded of the people." No one objects very much to technicalities in a game or on board a yacht, and they are clearly necessary for terse and precise scientific description. It is certain, however, that they can be reduced to a minimum without sacrificing accuracy, when the object in view is to explain "the gist of the matter." So this OUTLINE OF SCIENCE is meant for the general reader, who lacks both time and opportunity for special study, and yet would take an intelligent interest in the progress of science which is making the world always new.

The story of the triumphs of modern science is one of which Man may well be proud. Science reads the secret of the distant star and anatomises the atom; foretells the date of the comet's return and predicts the kinds of chickens that will hatch from a dozen eggs; discovers the laws of the wind that bloweth where it listeth and reduces to order the disorder of disease. Science is always setting forth on Columbus voyages, discovering new worlds and conquering them by understanding. For Knowledge means Foresight and Foresight means Power.

The idea of Evolution has influenced all the sciences, forcing us to think of _everything_ as with a history behind it, for we have travelled far since Darwin's day. The solar system, the earth, the mountain ranges, and the great deeps, the rocks and crystals, the plants and animals, man himself and his social institutions--all must be seen as the outcome of a long process of Becoming. There are some eighty-odd chemical elements on the earth to-day, and it is now much more than a suggestion that these are the outcome of an inorganic evolution, element giving rise to element, going back and back to some primeval stuff, from which they were all originally derived, infinitely long ago. No idea has been so powerful a tool in the fashioning of New Knowledge as this simple but profound idea of Evolution, that the present is the child of the past and the parent of the future. And with the picture of a continuity of evolution from nebula to social systems comes a promise of an increasing control--a promise that Man will become not only a more accurate student, but a more complete master of his world.

It is characteristic of modern science that the whole world is seen to be more vital than before. Everywhere there has been a passage from the static to the dynamic. Thus the new revelations of the constitution of matter, which we owe to the discoveries of men like Professor Sir J. J. Thomson, Professor Sir Ernest Rutherford, and Professor Frederick Soddy, have shown the very dust to have a complexity and an activity heretofore unimagined. Such phrases as "dead" matter and "inert" matter have gone by the board.

The new theory of the atom amounts almost to a new conception of the universe. It bids fair to reveal to us many of nature's hidden secrets. The atom is no longer the indivisible particle of matter it was once understood to be. We know now that there is an atom within the atom--that what we thought was elementary can be dissociated and broken up. The present-day theories of the atom and the constitution of matter are the outcome of the comparatively recent discovery of such things as radium, the X-rays, and the wonderful revelations of such instruments as the spectroscope and other highly perfected scientific instruments.

The advent of the electron theory has thrown a flood of light on what before was hidden or only dimly guessed at. It has given us a new conception of the framework of the universe. We are beginning to know and realise of what matter is made and what electric phenomena mean. We can glimpse the vast stores of energy locked up in matter. The new knowledge has much to tell us about the origin and phenomena, not only of our own planet, but other planets, of the stars, and the sun. New light is thrown on the source of the sun's heat; we can make more than guesses as to its probable age. The great question to-day is: is there _one_ primordial substance from which all the varying forms of matter have been evolved?

But the discovery of electrons is only one of the revolutionary changes which give modern science an entrancing interest.

As in chemistry and physics, so in the science of living creatures there have been recent advances that have changed the whole prospect. A good instance is afforded by the discovery of the "hormones," or chemical messengers, which are produced by ductless glands, such as the thyroid, the supra-renal, and the pituitary, and are distributed throughout the body by the blood. The work of physiologists like Professor Starling and Professor Bayliss has shown that these chemical messengers regulate what may be called the "pace" of the body, and bring about that regulated harmony and smoothness of working which we know as health. It is not too much to say that the discovery of hormones has changed the whole of physiology. Our knowledge of the human body far surpasses that of the past generation.

The persistent patience of microscopists and technical improvements like the "ultramicroscope" have greatly increased our knowledge of the invisible world of life. To the bacteria of a past generation have been added a multitude of microscopic _animal_ microbes, such as that which causes Sleeping Sickness. The life-histories and the weird ways of many important parasites have been unravelled; and here again knowledge means mastery. To a degree which has almost surpassed expectations there has been a revelation of the intricacy of the stones and mortar of the house of life, and the microscopic study of germ-cells has wonderfully supplemented the epoch-making experimental study of heredity which began with Mendel. It goes without saying that no one can call himself educated who does not understand the central and simple ideas of Mendelism and other new departures in biology.

The procession of life through the ages and the factors in the sublime movement; the peopling of the earth by plants and animals and the linking of life to life in subtle inter-relations, such as those between flowers and their insect-visitors; the life-histories of individual types and the extraordinary results of the new inquiry called "experimental embryology"--these also are among the subjects with which this OUTLINE will deal.

The behaviour of animals is another fascinating study, leading to a provisional picture of the dawn of mind. Indeed, no branch of science surpasses in interest that which deals with the ways and habits--the truly wonderful devices, adaptations, and instincts--of insects, birds, and mammals. We no longer deny a degree of intelligence to some members of the animal world--even the line between intelligence and reason is sometimes difficult to find.

Fresh contacts between physiology and the study of man's mental life; precise studies of the ways of children and wild peoples; and new methods like those of the psycho-analyst must also receive the attention they deserve, for they are giving us a "New Psychology" and the claims of psychical research must also be recognised by the open-minded.

The general aim of the OUTLINE is to give the reader a clear and concise view of the essentials of present-day science, so that he may follow with intelligence the modern advance and share appreciatively in man's continued conquest of his kingdom.

J. ARTHUR THOMSON.

I

THE ROMANCE OF THE HEAVENS

THE SCALE OF THE UNIVERSE--THE SOLAR SYSTEM

§ 1

The story of the triumphs of modern science naturally opens with Astronomy. The picture of the Universe which the astronomer offers to us is imperfect; the lines he traces are often faint and uncertain. There are many problems which have been solved, there are just as many about which there is doubt, and notwithstanding our great increase in knowledge, there remain just as many which are entirely unsolved.

The problem of the structure and duration of the universe [said the great astronomer Simon Newcomb] is the most far-reaching with which the mind has to deal. Its solution may be regarded as the ultimate object of stellar astronomy, the possibility of reaching which has occupied the minds of thinkers since the beginning of civilisation. Before our time the problem could be considered only from the imaginative or the speculative point of view. Although we can to-day attack it to a limited extent by scientific methods, it must be admitted that we have scarcely taken more than the first step toward the actual solution.... What is the duration of the universe in time? Is it fitted to last for ever in its present form, or does it contain within itself the seeds of dissolution? Must it, in the course of time, in we know not how many millions of ages, be transformed into something very different from what it now is? This question is intimately associated with the question whether the stars form a system. If they do, we may suppose that system to be permanent in its general features; if not, we must look further for our conclusions.

The Heavenly Bodies

The heavenly bodies fall into two very distinct classes so far as their relation to our Earth is concerned; the one class, a very small one, comprises a sort of colony of which the Earth is a member. These bodies are called _planets_, or wanderers. There are eight of them, including the Earth, and they all circle round the sun. Their names, in the order of their distance from the sun, are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and of these Mercury, the nearest to the sun, is rarely seen by the naked eye. Uranus is practically invisible, and Neptune quite so. These eight planets, together with the sun, constitute, as we have said, a sort of little colony; this colony is called the Solar System.

The second class of heavenly bodies are those which lie _outside_ the solar system. Every one of those glittering points we see on a starlit night is at an immensely greater distance from us than is any member of the Solar System. Yet the members of this little colony of ours, judged by terrestrial standards, are at enormous distances from one another. If a shell were shot in a straight line from one side of Neptune's orbit to the other it would take five hundred years to complete its journey. Yet this distance, the greatest in the Solar System as now known (excepting the far swing of some of the comets), is insignificant compared to the distances of the stars. One of the nearest stars to the earth that we know of is Alpha Centauri, estimated to be some twenty-five million millions of miles away. Sirius, the brightest star in the firmament, is double this distance from the earth.

We must imagine the colony of planets to which we belong as a compact little family swimming in an immense void. At distances which would take our shell, not hundreds, but millions of years to traverse, we reach the stars--or rather, a star, for the distances between stars are as great as the distance between the nearest of them and our Sun. The Earth, the planet on which we live, is a mighty globe bounded by a crust of rock many miles in thickness; the great volumes of water which we call our oceans lie in the deeper hollows of the crust. Above the surface an ocean of invisible gas, the atmosphere, rises to a height of about three hundred miles, getting thinner and thinner as it ascends.

Except when the winds rise to a high speed, we seem to live in a very tranquil world. At night, when the glare of the sun passes out of our atmosphere, the stars and planets seem to move across the heavens with a stately and solemn slowness. It was one of the first discoveries of modern astronomy that this movement is only apparent. The apparent creeping of the stars across the heavens at night is accounted for by the fact that the earth turns upon its axis once in every twenty-four hours. When we remember the size of the earth we see that this implies a prodigious speed.