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THE
OUTLINE OF SCIENCE
A PLAIN STORY SIMPLY TOLD
EDITED BY
J. ARTHUR THOMSON
REGIUS PROFESSOR OF NATURAL HISTORY IN THE
UNIVERSITY OF ABERDEEN
WITH OVER 800 ILLUSTRATIONS
OF WHICH ABOUT 40 ARE IN COLOUR
IN FOUR VOLUMES
G. P. PUTNAM'S SONS
NEW YORK AND LONDON
The Knickerbocker press
Copyright, 1922
by
G. P. Putnam's Sons
First Printing April, 1922
Second Printing April, 1922
Third Printing April, 1922
Fourth Printing April, 1922
Fifth Printing June, 1922
Sixth Printing June, 1922
Seventh Printing June, 1922
Eighth Printing June, 1922
Ninth Printing August, 1922
Tenth Printing September, 1922
Eleventh Printing Sept., 1922
Twelfth Printing, May, 1924
Made in the United States of America
INTRODUCTORY NOTE
By Professor J. Arthur Thomson
Was it not the great philosopher and mathematician Leibnitz who said that the more knowledge advances the more it becomes possible to condense it into little books? Now this "Outline of Science" is certainly not a little book, and yet it illustrates part of the meaning of Leibnitz's wise saying. For here within reasonable compass there is a library of little books—an outline of many sciences.
It will be profitable to the student in proportion to the discrimination with which it is used. For it is not in the least meant to be of the nature of an Encyclopædia, giving condensed and comprehensive articles with a big full stop at the end of each. Nor is it a collection of "primers," beginning at the very beginning of each subject and working methodically onwards. That is not the idea.
What then is the aim of this book? It is to give the intelligent student-citizen, otherwise called "the man in the street," a bunch of intellectual keys by which to open doors which have been hitherto shut to him, partly because he got no glimpse of the treasures behind the doors, and partly because the portals were made forbidding by an unnecessary display of technicalities. Laying aside conventional modes of treatment and seeking rather to open up the subject as one might on a walk with a friend, the work offers the student what might be called informal introductions to the various departments of knowledge. To put it in another way, the articles are meant to be clues which the reader may follow till he has left his starting point very far behind. Perhaps when he has gone far on his own he will not be ungrateful to the simple book of "instructions to travellers" which this "Outline of Science" is intended to be. The simple "bibliographies" appended to the various articles will be enough to indicate "first books." Each article is meant to be an invitation to an intellectual adventure, and the short lists of books are merely finger-posts for the beginning of the journey.
We confess to being greatly encouraged by the reception that has been given to the English serial issue of "The Outline of Science." It has been very hearty—we might almost say enthusiastic. For we agree with Professor John Dewey, that "the future of our civilisation depends upon the widening spread and deepening hold of the scientific habit of mind." And we hope that this is what "The Outline of Science" makes for. Information is all to the good; interesting information is better still; but best of all is the education of the scientific habit of mind. Another modern philosopher, Professor L. T. Hobhouse, has declared that the evolutionist's mundane goal is "the mastery by the human mind of the conditions, internal as well as external, of its life and growth." Under the influence of this conviction "The Outline of Science" has been written. For life is not for science, but science for life. And even more than science, to our way of thinking, is the individual development of the scientific way of looking at things. Science is our legacy; we must use it if it is to be our very own.
CONTENTS
Introduction 3 I. 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.ILLUSTRATIONS
FACING PAGE The Great Scarlet Solar Prominences, Which are Such a Notable Feature of the Solar Phenomena, are Immense Outbursts of Flaming Hydrogen Rising Sometimes to a Height of 500,000 Miles Coloured Frontispiece Laplace 10 Professor J. C. Adams 10 Photo: Royal Astronomical Society. Professor Eddington of Cambridge University 10 Photo: Elliot & Fry, Ltd. The Planets, Showing their Relative Distances and Dimensions 11 The Milky Way 14 Photo: Harvard College Observatory. The Moon Entering the Shadow Cast by the Earth 14 The Great Nebula in Andromeda, Messier 31 15 From a photograph taken at the Yerkes Observatory. Diagram Showing the Main Layers of the Sun 18 Solar Prominences Seen at Total Solar Eclipse, May 29, 1919. Taken at Sobral, Brazil 18 Photo: Royal Observatory, Greenwich. The Visible Surface of the Sun 19 Photo: Mount Wilson Observatory. The Sun Photographed in the Light of Glowing Hydrogen 19 Photo: Mount Wilson Observatory. The Aurora Borealis (Coloured Illustration) 20 Reproduced from The Forces of Nature (Messrs. Macmillan) The Great Sun-Spot of July 17, 1905 22 Yerkes Observatory. Solar Prominences 22 From photographs taken at the Yerkes Observatory. Mars, October 5, 1909 23 Photo: Mount Wilson Observatory. Jupiter 23 Saturn, November 19, 1911 23 Photo: Professor E. E. Barnard, Yerkes Observatory. The Spectroscope, an Instrument for Analysing
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Light; it Provides Means for Identifying Substances (Coloured Illustration) 24 The Moon 28 Mars 29 Drawings by Professor Percival Lowell. The Moon, at Nine and Three Quarter Days 29 A Map of the Chief Plains and Craters of the Moon 32 A Diagram of a Stream of Meteors Showing the Earth Passing Through Them 32 Comet, September 29, 1908 33 Photo: Royal Observatory, Greenwich. Comet, October 3, 1908 33 Photo: Royal Observatory, Greenwich. Typical Spectra 36 Photo: Harvard College Observatory. A Nebular Region South of Zeta Orionis 37 Photo: Mount Wilson Observatory. Star Cluster in Hercules 37 Photo: Astrophysical Observatory, Victoria, British Columbia. The Great Nebula in Orion 40 Photo: Yerkes Observatory. Giant Spiral Nebula, March 23, 1914 41 Photo: Lick Observatory. A Spiral Nebula Seen Edge-on 44 Photo: Mount Wilson Observatory. 100-Inch Telescope, Mount Wilson 45 Photo: H. J. Shepstone. The Yerkes 40-Inch Refractor 48 The Double-Slide Plate-Holder on Yerkes 40-Inch Refracting Telescope 49 Photo: H. J. Shepstone. Modern Direct-Reading Spectroscope 49 By A. Hilger, Ltd. Charles Darwin 56 Photo: Rischgitz Collection. Lord Kelvin 56 Photo: Rischgitz Collection. A Giant Spiral Nebula 57 Photo: Lick Observatory. Meteorite Which Fell Near Scarborough and is now to be Seen in the Natural History Museum 57 Photo: Natural History Museum. A Limestone Canyon 60 Reproduced from the Smithsonian Report, 1915. Geological Tree of Animals 61 Diagram of Amœba 61 A Piece of a Reef-Building Coral, Built up by a Large Colony of Small Sea-Anemone-Like Polyps, Each of which Forms from the Salts of the Sea a Skeleton or Shell of Lime 64 From the Smithsonian Report, 1917. A Group of Chalk-Forming Animals, or Foraminifera, Each about the Size of a Very Small Pin's Head 65 Photo: J. J. Ward, F.E.S. A Common Foraminifer (Polystomella) Showing the Shell in the Centre and the Outflowing Network of Living Matter, Along which Granules are Continually Travelling, and by which Food Particles are Entangled and Drawn in 65 Reproduced by permission of the Natural History Museum (after Max Schultze). A Plant-Like Animal, or Zoophyte, Called Obelia 68 Photo: J. J. Ward, F.E.S. Trypanosoma Gambiense 69 Reproduced by permission of The Quart. Journ. Mic. Sci. Volvox 69 Proterospongia 69 Green Hydra 72 Photo: J. J. Ward, F.E.S. Diagram Illustrating the Beginning of Individual Life 72 Earthworm 72 Photo: J. J. Ward, F.E.S. Glass Model of a Sea-Anemone 72 Reproduced from the Smithsonian Report, 1917. This Drawing Shows the Evolution of the Brain from Fish to Man 73 Okapi and Giraffe (Coloured Illustration) 74 Diagram of a Simple Reflex Arc in a Backboneless Animal Like an Earthworm 76 The Yucca Moth 76 Photo: British Museum (Natural History). Inclined Plane of Animal Behaviour 76 Venus' Fly-Trap 77 Photo: J. J. Ward, F.E.S. A Spider Sunning Her Eggs 77 Reproduced by permission from The Wonders of Instinct by J. H. Fabre. The Hoatzin Inhabits British Guiana 82 Peripatus 83 Photograph, from the British Museum (Natural History), of a drawing by Mr. E. Wilson. Rock Kangaroo Carrying its Young in a Pouch 83 Photo: W. S. Berridge, F.Z.S. Professor Thomas Henry Huxley (1825-95) 86 Photo: Rischgitz. Baron Cuvier, 1769-1832 86 An Illustration Showing Various Methods of Flying and Swooping
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tag="{http://www.w3.org/1999/xhtml}a">87 Animals of the Cambrian Period 90 From Knipe's Nebula to Man. A Trilobite 90 Photo: J. J. Ward, F.E.S. The Gambian Mud-Fish, Protopterus 91 Photo: British Museum (Natural History). The Archæopteryx 91 After William Leche of Stockholm. Wing of a Bird, Showing the Arrangement of the Feathers 91 Pictorial Representation of Strata of the Earth's Crust, with Suggestions of Characteristic Fossils (Coloured Illustration) 92 Fossil of a Pterodactyl or Extinct Flying Dragon 94 Photo: British Museum (Natural History). Pariasaurus: An Extinct Vegetarian Triassic Reptile 94 From Knipe's Nebula to Man. Triceratops: A Huge Extinct Reptile 95 From Knipe's Nebula to Man. The Duckmole or Duck-Billed Platypus of Australia 95 Photo: Daily Mail. Skeleton of an Extinct Flightless Toothed Bird, Hesperornis 100 After Marsh. Six Stages in the Evolution of the Horse, Showing Gradual Increase in Size 101 After Lull and Matthew. Diagram Showing Seven Stages in the Evolution of the Fore-Limbs and Hind-Limbs of the Ancestors of the Modern Horse, Beginning with the Earliest Known Predecessors of the Horse and Culminating with the Horse of To-Day 104 After Marsh and Lull. What is Meant by Homology? Essential Similarity of Architecture, though the Appearances May be Very Different 105 An Eight-Armed Cuttlefish or Octopus Attacking a Small Crab 116 A Common Starfish, which has Lost Three Arms and is Regrowing Them 116 After Professor W. C. McIntosh. The Paper Nautilus (Argonauta), an Animal of the Open Sea 117 Photo: J. J. Ward, F.E.S. A Photograph Showing a Starfish (Asterias Forreri) which has Captured a Large Fish 117 Ten-Armed Cuttlefish or Squid in the Act of Capturing a Fish 118 Greenland Whale 118 Minute Transparent Early Stage of a Sea-Cucumber 119 An Intricate Colony of Open-Sea Animals (Physophora Hydrostatica) Related to the Portuguese Man-of-War 119 Photo: British Museum (Natural History). A Scene in the Great Depths 119 Sea-Horse in Sargasso Weed 120 Large Marine Lampreys (Petromyzon Marinus) 120 The Deep-Sea Fish Chiasmodon Niger 120 Deep-Sea Fishes 120 Flinty Skeleton of Venus' Flower Basket (Euplectella), a Japanese Deep-Sea Sponge 121 Egg Depository of Semotilus Atromaculatus 121 The Bitterling (Rhodeus Amarus) 124 Woolly Opossum Carrying her Family 124 Photo: W. S. Berridge. Surinam Toad (Pipa Americana) with Young Ones Hatching out of Little Pockets on her Back 125 Storm Petrel or Mother Carey's Chicken (Procellaria Pelagica) 125 Albatross: A Characteristic Pelagic Bird of the Southern Sea 128 The Praying Mantis (Mantis Religiosa) 138 Protective Coloration: A Winter Scene in North Scandinavia 138 The Variable Monitor (Varanus) 139 Photo: A. A. White. Banded Krait: A Very Poisonous Snake with Alternating Yellow and Dark Bands 140 Photo: W. S. Berridge, F.Z.S. The Warty Chameleon 140 Photos: W. S. Berridge, F.Z.S. Seasonal Colour-Change: Summer Scene in North Scandinavia 141 Protective Resemblance 142 Photo: J. J. Ward, F.E.S. When Only a Few Days Old, Young Bittern Begin to Strike the Same Attitude as their Parents, Thrusting their Bills upwards and Drawing their Bodies up so that they Resemble a Bunch of Reeds 143 Protective Coloration or Camouflaging, Giving Animals a Garment of Invisibility (Coloured Illustration) 144 Another Example of Protective Coloration (Coloured Illustration) 144 Dead-Leaf Butterfly (Kallima Inachis) from India 146 Protective Resemblance between a Small Spider (to the left) and an Ant (to the right) 146 The Wasp Beetle, which, when Moving amongst the Branches, Gives a Wasp-Like Impression 147 Photo: J. J. Ward, F.E.S. Hermit-Crab with Partner Sea-Anemones
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147 Cuckoo-Spit 147 Photo: G. P. Duffus. Chimpanzee, Sitting 156 Photo: New York Zoological Park. Chimpanzee, Illustrating Walking Powers 156 Photo: New York Zoological Park. Surface View of the Brains of Man and Chimpanzee 157 Side-View of Chimpanzee's Head 157 Photo: New York Zoological Park. Profile View of Head of Pithecanthropus, the Java Ape-Man, Reconstructed from the Skull-Cap 157 After a model by J. H. McGregor. The Flipper of a Whale and the Hand of a Man 157 The Gorilla, Inhabiting the Forest Tract of the Gaboon in Africa (Coloured Illustration) 158 "Darwin's Point" on Human Ear 160 Professor Sir Arthur Keith, M.D., LL.D., F.R.S. 161 Photo: J. Russell & Sons. Skeletons of the Gibbon, Orang, Chimpanzee, Gorilla, Man 161 After T. H. Huxley (by permission of Messrs. Macmillan). Side-View of Skull of Man and Gorilla 164 The Skull and Brain-Case of Pithecanthropus, the Java Ape-Man, as Restored by J. H. McGregor from the Scanty Remains 164 Suggested Genealogical Tree of Man and Anthropoid Apes 165 The Gibbon is Lower than the Other Apes as Regards its Skull and Dentition, but it is highly Specialized in the Adaptation of its Limbs to Arboreal Life 166 Photo: New York Zoological Park. The Orang Has a High Rounded Skull and a Long Face 166 Photo: New York Zoological Park. Comparisons of the Skeletons of Horse and Man 167 Photo: British Museum (Natural History). A Reconstruction of the Java Man (Coloured Illustration) 168 Profile View of the Head of Pithecanthropus, the Java Ape-Man—an Early Offshoot from the Main Line of Man's Ascent 170 After a model by J. H. McGregor. Piltdown Skull 170 From the reconstruction by J. H. McGregor. Sand-Pit at Mauer, near Heidelberg: Discovery Site of the Jaw of Heidelberg Man 171 Reproduced by permission from Osborn's Men of the Old Stone Age. Paintings on the Roof of the Altamira Cave in Northern Spain, Showing a Bison and a Galloping Boar (Coloured Illustration) 172 Piltdown Man, Preceding Neanderthal Man, Perhaps 100,000 to 150,000 Years Ago 174 After the restoration modelled by J. H. McGregor. The Neanderthal Man of La Chapelle-aux-Saints 175 After the restoration modelled by J. H. McGregor. Restoration by A. Forestier of the Rhodesian Man whose Skull was Discovered in 1921 176-177 Side View of a Prehistoric Human Skull Discovered in 1921 in Broken Hill Cave, Northern Rhodesia 178 Photo: British Museum (Natural History). A Cromagnon Man or Cromagnard, Representative of a Strong Artistic Race Living in the South of France in the Upper Pleistocene, Perhaps 25,000 Years Ago 178 After the restoration modelled by J. H. McGregor. 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
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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
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href="@public@vhost@g@gutenberg@html@files@20417@[email protected]#image414a" class="pginternal" tag="{http://www.w3.org/1999/xhtml}a">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.