SECRETS OF EARTH AND SEA

DIMETRODON GIGAS, AN EXTINCT LIZARD, SEVEN FEET LONG

SECRETS OF EARTH AND SEA

BY
Sir RAY LANKESTER
K.C.B., F.R.S.

WITH NUMEROUS ILLUSTRATIONS

NEW YORK
THE MACMILLAN COMPANY
1920

PREFACE

THE present volume is, like its predecessors, "Science from an Easy Chair" (Series I and Series II) and "Diversions of a Naturalist"—mainly a revision and reprint—with considerable additions—of articles published in daily or weekly journals. The first chapter appeared originally in "The Field." The Chapters VI, XX, XXI, and XXII were published in the "Illustrated London News," under the title "About a Number of Things." The rest are some of the articles which, as "Science from an Easy Chair," I contributed, during seven years, to the "Daily Telegraph." That, to me very happy, conjunction was, like so many other happy things, necessarily interrupted by the Great War.

One result of that terrible cataclysm is that not a few thoughtful writers have been led to deny the existence of what they call "Progress," meaning by that word the development of mankind from a less to a more complete attainment of moral and physical well-being. The question raised is obscured by the arbitrary use of the word "progress," since by it any movement from point to point—whether advantageous and desirable or the reverse—is described, as, for instance, in the familiar titles given by Bunyan to his book "The Pilgrim's Progress" and by Hogarth to his pictures "The Rake's Progress." Those who to-day despair of man's future limit their outlook on the past to the conventional history of some three or four thousand years. The only solid ground upon which we can base the supposition that mankind has moved from a less to a more complete attainment of moral and physical well-being and will continue to do so, exists in the ascertained facts of the past history of living things on this Earth, and of man since his earliest emergence from among the man-like apes made known to us by his stone-implements and fossilized bones. That there has been a development from lower, simpler structure to higher, more complex, more efficient structure is demonstrable, and so is the proposition that there has been in the human race a continuous development in the direction of increased adaptation to the conditions of social life and an increased control by man of those natural agencies which he can either favour when conducive to his prosperity, or on the other hand can arrest when inimical to it. "The continuous weakening of selfishness and the continuous strengthening of sympathy" (to adopt the words of the American philosopher, Fiske) are, in spite of numerous lapses and outbursts of savagery, patent features of the long history of mankind. We have no reason to doubt their continuation, whilst at the same time we must be prepared for and accept, without desponding, the ups and the downs, the disasters as well as the triumphs, which inevitably characterize the natural process of evolution. One thing, above all others, we as conscious, reasoning beings can do which must tend to the further development and security of human well-being: we can ascertain ever more and more of the truth, or in other words, "that which is." We can discover the actual conditions of natural law, under which we exist and promote the knowledge of that truth among our fellows. To do that which is right, we must know that which is true. To act rightly, we must know truly.

We possess, a vast heritage of knowledge handed on to us in tradition and in writings from our father-man in the past. But there are yet immense fields of knowledge to be explored and yet a greater task to be accomplished in spreading the knowledge which we possess, and in persuading all men that it is their right and their duty to acquire it and to enjoy the power and the pleasure which it gives. All must also help, directly or indirectly, in the making of new knowledge. Whilst mankind is still so backward in knowledge and the worship of wisdom, it is idle to indulge in despair of the future. A chief way to increased welfare is still open and untrodden.

These are big speculations and problems with which to preface a small book. But I am content to offer the small book as a contribution, however restricted, to the spread of a desire for further knowledge of the things about which it tells—a possible incitement to serious study of some one or other among them.

E. RAY LANKESTER

June 2nd, 1920

CONTENTS

EXPLANATION OF THE FRONTISPIECE

THIS plate shows the restoration of the extinct lizard, Dimetrodon gigas (Cope), lately made by Mr. Charles W. Gilmore of the United States National Museum, by whose kind permission it is here reproduced from the Proceedings of the U.S. National Museum, vol. 56, 1919. It is based upon the study of a very fine skeleton and some hundred bones of allied species, collected by Mr. Sternberg from "the Permian formation" exposed in the vicinity of Seymour, Texas, U.S.A. It is selected for illustration here because its most striking feature—the high dorsal fin-like crest along the middle of the back formed by the elongation of the neural spines of the vertebræ—is a puzzle to the conscientious Darwinian. Professor Case says of it: "The elongate spines were useless, so far as I can imagine, and I have been puzzling over them for several years. It is impossible to conceive of them as useful either for defence or concealment, or in any other way than as a great burden to the creatures (terrestrial non-aquatic animals) that bore them. They must have been a nuisance in getting through the vegetation, and a great drain upon the creature's vitality, both to develop them and keep them in repair." The reader is referred to pp. 127, 128, where a brief discussion of such exuberant growths will be found. The excessive growth of the median fins in the fish Pteraclis allied to the Dolphin which displays changing floods of surface colour as it dies—and in the Australian Blenny called Patæcus—both figured on p. 130—should be compared with that of the strange crest of the grotesque Dimetrodon.

LIST OF ILLUSTRATIONS

SECRETS OF EARTH AND SEA

CHAPTER I

THE EARLIEST PICTURE IN THE WORLD

IN Figs. 1 and 2 on the next page a cylindrical piece of the antler of a red deer is represented of half the natural size. On it are carved by in-sunk lines certain representations of animals. It was found in the cavern of Lortet, near Lourdes, in the department of the Hautes Pyrénées, in the south of France, together with many other remains of prehistoric man. This cavern was excavated and all its contents of human origin carefully preserved by M. Edouard Piette in 1873 and the following years. Drawings of this and other remarkable carved pieces of bone and antler, many in the form of harpoon heads, and of small chipped flint implements, all found in this cave, were published by him. [1] He excavated also several other caverns with great care, and his collections were bequeathed by him on his death to the great Museum of National Archæology at St. Germain, near Paris, where I have had the advantage of studying them.

Figs. 1 and 2.–Engraved cylinder of red-deer's antler, from the Azilian (Elapho-Tarandian) horizon of the cavern of Lortet. Drawn of a little more than half the actual size of the specimen.

The age assigned to this carving is that called by Piette "Elapho-Tarandian." At this period the reindeer (Tarandus), which previously abounded, is giving place to the red deer (Elaphus). The layer in which this carving was found belongs to the latest of the Palæolithic cave deposits, and was followed by a warmer period, in which the red deer and the modern fauna entirely replaced the old fauna of the Glacial period. The deposits in Pyrenean caves of the Elapho-Tarandian age are characterized by an abundance of large flat harpoons serrated on both sides. In this latest horizon of the Reindeer period the art of engraving in outline on bone and stone had attained the highest pitch of excellence which it reached in the prehistoric race of South-West Europe.

Fig. 3.–A. Perforated harpoon of the Azilian or Red-Deer period, made from antler of red deer, found in quantity in the upper layers of deposit in the cavern of the Mas d'Azil (Arriège). B and C. Imperforate harpoons or lance heads made from reindeer antler of the Magdalenian period (Reindeer epoch). B from Bruniquel Cave (Tarn-et-Garonne). C from a cavern in the Hautes Pyrénées. Same size as the objects.

A very natural tendency among those who hear from time to time something of what is being discovered about primitive man is to confuse all the periods and races of prehistoric man together, and so picture to themselves one ideal "primitive man." My friend Mr. Rudyard Kipling does this, although it would be no further from a true conception were he to blend his ancient Britons, his Phenicians, his Romans, his Saxons, his Normans, and a few Hindoos into one imaginary man and represent him as taking a coloured photograph of the Druids of Stonehenge on a piece of Egyptian papyrus. Here is Mr. Kipling's vision of primitive man:

Once on a glittering icefield, ages and ages ago,

Ung, a maker of pictures, fashioned an image of snow.

Later he pictured an aurochs, later he pictured a bear–

Pictured the sabre-tooth tiger dragging a man to his lair–

Pictured the mountainous mammoth, hairy, abhorrent, alone–

Out of the love that he bore them, scribing them clearly on bone,

Straight on the glittering icefield, by the caves of the lost Dordogne,

Ung, a maker of pictures, fell to his scribing on bone.

The fact is that several prehistoric races have succeeded one another in Western Europe during the immensely long period—amounting to hundreds of thousands of years—during which man existed before the dawn of history. The "lost" or "prehistoric Dordogne" was like the present historic Dordogne in regard to the fact that many races and dynasties successively held possession of it and left their work in its soil and caves.

Passing back through the historic age of iron and the sub-historic age of bronze, we come to a time, about four thousand years ago, when there were no men in the west of Europe who made use of metals at all, although, for a thousand or two years earlier, men were using bronze and copper in the East. European races immediately before the first use of metals made beautiful implements of stone (chiefly flint), and finished them by grinding and polishing them. These men are spoken of as Neolithic men, or men of the Neolithic period. They had herds and cultivated crops, and they built after a fashion rough houses in wood and tombs and temples with great slabs of stone. They made pottery and woven cloth. The animals and plants of Europe were the same in those late prehistoric times as they are to-day. The Lake dwellings of Switzerland belong to this epoch and yield us their remains as evidence. The men had very nearly the same set of domesticated animals as we have to-day, but they had no skill in carving outlines of animals. Their only decorative work consisted of parallel lines, straight or in zigzags or in circles, graven on the great stone slabs which they erected.

We can trace them back to some seven thousand years B.C. and then comes a huge gap—we do not know how many thousand years—in our evidence as to what was going on in this part of the world. We find convincing proof that before this interval the climate was much colder than it is to-day, and that the land surface of Europe was in many respects very different from what it became later. Britain was continuous with the Continent. There were in that remote period human tribes spread over the less frigid valleys of Europe. They had no fields, no herds; they fed on the roasted flesh of the animals they chased and on the fish they speared, and on wild fruits and roots. They dwelt chiefly, if not wholly, in caves, probably also in skin tents, but they did not build either in wood or in stone. The age which we thus reach is called the Palæolithic, or "ancient" Stone age, because men made use of stone, which they chipped into shape, but, unlike the Neolithic people, never polished it. We find enormous numbers of these rough or Palæolithic stone implements both in caves and in the gravels deposited in the ancient beds of rivers. They are so abundant as to prove the existence of a very considerable human population in the remote ages when they were fashioned and used. The changes which have taken place and the time involved since some of these Palæolithic implements were made and used may be guessed at (but cannot be definitely calculated) from the fact that the beds of the rivers which formed the gravel terraces in which they are found in England were, in many cases, from one to six hundred feet above the level of the present rivers. The land surface has risen and the rivers have simultaneously excavated deep and wide valleys leaving terraces of gravel high up on their sides. These show where the rivers once flowed. The vastness of the excavation of the valley from the level of the old river bed 600 ft. up on the sloping hill-side to its present low-lying bed in the floor of the valley—gives us some measure of the time which has elapsed in the process.

No one can tell, at present, the limit in the past of Palæolithic man. The period of time over which his existence extended, as indicated by the trimmed flints undoubtedly made by human workmanship, is a matter of hundreds of thousands of years. In Western Europe races came and went, succeeded one another and disappeared, either migrating or absorbed or more rarely destroyed by the later invaders. Naturally enough, in the later deposits of rivers and in the higher layers of earth and limestone cake which fill many caves to the depth of 30 or 40 ft. we find the remains of man's workmanship more abundantly than in the older deposits.

We can broadly distinguish in the Palæolithic epoch three (perhaps four) periods, separated by the occurrence of great extensions of the northern or arctic ice cap of such a volume as to cover North Europe and North America, and the simultaneous extension of the glaciers of the mountains of Europe. This period of the alternating extension and retreat of the great northern glaciers is known as the Glacial period, or Ice Age. The latest Palæolithic men are subsequent to it—that is, post-Glacial. We can distinguish several successive ages of these post-Glacial Palæolithic men, altogether distinct from and anterior to the Neolithic men. In the earlier of these ages many of the great animals of the Glacial period—now extinct or withdrawn to other regions—still survived in Europe. The mammoth survived, but was fast dying out in the south and centre of France, and we find its outline scratched on ivory and on bone by the early post-Glacial men. The lion still survived in Europe, also the hyena, the bear and the rhinoceros. The reindeer seems to have been especially abundant, and to have been associated with the men of this period. The horse was very abundant, and was largely eaten by the earlier post-Glacial people. From the first these men show extraordinary artistic skill, and have left in their caves many carvings on ivory, bone and stone. In the oldest deposits of the post-Glacial age the carvings are complete all-round sculptures of small size or carvings in low relief, all of rough primitive workmanship. Larger life-size sculptures in rock are also found. In later deposits we find better sculpture and also engraving on flat pieces of bone and ivory, and also on stone. This art persisted, and attained its greatest perfection in the latest deposits of all in which the work of Palæolithic man is found. The reindeer persisted through this post-Glacial period (hence often called "the reindeer period") until the gradual increase of temperature and change of herbage and forest led to its migration northwards and to the relative abundance of the red deer. It is to this latest period—the Elapho-Tarandian of Piette—that the engraved antler figured here (Figs. 1 and 2) belongs.

At an earlier stage of the post-Glacial period men hunted the bison and other large game in the north of Spain and made coloured drawings of them on the roofs and walls of their caves, drawings which have been copied and preserved: whilst the mammoth, the rhinoceros, the cave lion and bear still inhabited south central France and are pictured on the walls of caves in that region—as described in Chapter II. Later we lose all trace of Palæolithic man and his wonderful artistic skill. He seems either to have migrated or to have been absorbed in the immigrant Neolithic race—a race singularly devoid of any tendency to artistic sculpture or engraving.

The skeletons and skulls of the men of the Reindeer period, or post-Glacial Palæolithic men, have been discovered here and there. They indicate a fine, tall people with well-shaped skulls and jaws, comparable to the nobler modern races. It is convenient to call them Cromagnards, since good skulls of the race have been described from Cromagnon, in France. There is evidence (from skulls) that another race (the negroid so called "Aurignacians") preceded and coexisted to some extent in Western Europe with them, but we have, at present, no evidence as to whence or how the Neolithic race or the Cromagnard race or any of their predecessors came upon the scene!

When we go farther back and reach the actual Glacial period we find a very different state of things. The men who then existed in the caverns are called the Neander men. They were a short, bandy-legged, long-armed, low-browed people, great workers of flints. They had the use of fire, and contended with hyenas and bears and lions for the occupation of their caverns. In their day—the day of European glaciation—the mammoth was in full occupation of the pine forests on the edge of the glaciers. But the Neander men made no sculptures, or carving, or engravings. The gap between them and the Cromagnon men is much greater than that between an Australian black fellow and an average Englishman; indeed, the difference is properly expressed by regarding the Neander man as a distinct species—Homo neanderthalensis.

Passing again farther back over an immense period of time, we find Europe warm again; the glaciers have (for a time) gone or retreated far up the mountains but are found in extension again at a still earlier date. An inter-Glacial set of animals is now found living in a comparatively warm climate in Western Europe. Another elephant (Elephas antiquus) is there (not the mammoth), and another rhinoceros (not the woolly rhinoceros of the later Glacial period); the hippopotamus flourished then in Europe and swam in the Thames and Severn, and there too, at last is the sabre-toothed tiger, which did not exist at all at a later period! Now was the time when a man, if he could, might have "scribed" the image of a sabre-toothed tiger on a piece of bone, but, so far as we know, he did not and could not. This was ages before other succeeding men walked "on glittering ice fields," and they, in turn, were ages earlier than the artistic Cromagnards of the Reindeer period.

The presence of men in the warm inter-Glacial times in Europe is proved by the association of rough but undisputed flint implements with the inter-Glacial animals and by the discovery of a most interesting human jaw (chinless, like that of the Neander men) in what is held to be a præ-Glacial deposit at Heidelberg. We have very little knowledge of Glacial and præ-Glacial man except well characterized flint implements and two skeletons, some detached limb bones, four or five jaws, and as many skulls. [2] But of post-Glacial Palæolithic man we know the skeletons of the Cromagnard race, their sepulture, their decorative necklaces, and their bone and ivory carvings and engravings, and the coloured rock paintings and other work of earlier races (the Aurignacians, and others) belonging to successive epochs or eras, which have been discovered in caves in France, Spain, Belgium, and Austria. It was long after them that the Neolithic people appeared.

The preceding remarks will have made it clear that the engraved antler here figured was carved by a man who was not really at all primitive, although he lived probably between twenty and fifty thousand years ago. It will also have been made clear that hundreds of such engravings, more or less fragmentary, are known. Some are very skilful works of art, others of a much inferior quality. Many, however, show an astonishing familiarity with the animal drawn and a sureness of drawing which is not surpassed by the work of modern artists (see Chapter III). The interest of the particular engraved antler which I am describing is that it is the only carving of its age as yet discovered which is more than a drawing or sculpture of a single animal. It is a "picture" in the sense of being a composition. It is not, it is true, painted—it is engraved; but being a composition it is entitled to be called "the earliest picture in the world." Let me describe it a little more fully with the help of the illustrations.

The engraving has been made on a long cylindrical piece of the red deer's antler. It can hardly be considered as decorative, since the figures of the animals do not show as such on the cylindrical surface (Figs. 1 and 2). Pieces of antler, bone, and ivory carved with spiral scrolls and circles which are really decorative and effective as decoration are found in these caves (Fig. 29). But often such pieces as the present are met with. It has been discovered by French archæologists that the true intent of such engravings may be rendered evident by rolling the cylinder on a plastic substance (soft wax or similar material), when the drawing is "printed off" or "developed" as it is termed. A great number of such line engravings have been thus printed off or developed, and plaster casts made from the flat impressions are preserved in the museum of St. Germain, the engraved lines being rendered obvious by letting them fill with printing ink. They often give us in this way a "printed" drawing of remarkable accuracy and artistic quality. The rolled-off print of our specimen is shown in Fig. 4. The cylinder has been damaged by time, but the print shows, more or less completely, a vigorous outline drawing of three red deer, with six salmon-like fish placed in a decorative way above them and between their legs. Two lozenge-shaped outlines (above the larger stag) are held by good authorities to be the signature of the artist. The group of deer is represented in movement. The largest stag is on the right; his hindquarters are broken away by injury to the cylinder. He is commencing to advance, and turns his head backwards to see what is the thing which has alarmed him and his companions; at the same time his mouth is open, and he is "blowing." The second stag is a younger and smaller animal, and is retreating more rapidly. The cylinder is damaged so that, although all the four legs of this second stag are preserved, the head and neck are gone, though the points of the antlers are preserved. The same damage has removed all but the hind legs of the still younger animal who heads the group. The beauty of the drawing of these hind legs and the extraordinary impression of graceful, rapid movement given by their hanging pose, side by side, is not surpassed, even if it be equalled, by the work of any modern draughtsman. It is clear that the youngest and smallest member of the group is, as is natural, the most timid, and that he has sprung off with a sudden bound on the occurrence of the alarm from the rear, which is setting the whole group into motion with increasing velocity as we pass from right to left.

Fig. 4.—Rolled impression or "development" of the engraving on the Lortet antler.

Fig. 5.—Restoration (or completion) of the engraving on the Lortet antler, as now (1919) suggested by the writer (E. R. L.).

The "printed-off," or "unrolled," or "developed" picture given in Fig. 3 is an exact reproduction of a copy of the cast made and preserved in the Museum of National Antiquities at St. Germain, for which I am indebted to my friend M. Salomon Reinach, the distinguished archæologist who is the director of that museum. It is reproduced here, a little larger than half the size of the original, as are the representations of the carved cylinder itself (Figs. 1 and 2). In Fig. 4 we have my attempt to restore the damaged portions of the design and to present it as it was when the Palæolithic man completed it some 20,000 years ago.

I will return to the question of the correctness of this restoration, but before doing so I wish to mention some extremely interesting points as to the probable use of the cylinder of stag's antler and the purpose of the carving around its axis. In the first place, this and a few other of the pieces of carving of the post-Glacial period were certainly the work of highly gifted and practised artists. It is obvious that this work is far superior both in conception and execution to the more or less clever, often grotesque, carvings and paintings made by modern savages or simple pastoral folk. There is no reason to suppose that the Cromagnards, or men of the post-Glacial or Reindeer period of West Europe, differed from modern races in being universally gifted with artistic capacity. This engraving of three stags is almost certainly the work of a man who belonged to a family or guild of picture-makers who had cultivated such work for centuries and handed it on from master to apprentice. This design is probably one which had been perfected by many succeeding observers and draughtsmen. Its sureness of line and vivacity of movement are not the outcome of the sudden inspiration of an untutored savage, but are the result of the growth, cultivation, and development of artistic perception and the power of artistic execution in successive generations.

It seems in the highest degree improbable, if not impossible, that so excellent a drawing as this should have been cut on the cylindrical piece of antler by an engraver who never saw the flat or rolled-off impress of his design. One is driven to the conclusion that he must, as he worked on the bone, have taken an impress of the growing picture from time to time, using probably animal fat and charcoal as an "ink" and printing on to a piece of prepared skin or on to a birch-bark cloth. How otherwise could he have made his engraving so truly that when, ages afterwards, we print it off the cylinder, we are astonished and delighted by its perfection of design and execution? If this be once admitted—namely, that the artist tested and checked his work by printing it off as he proceeded with it—we gain what appears to me to be the probable solution of the question which has been largely debated, "For what were these carved cylinders or rods used?" Those which are simple cylindrical rods, such as the present one, must be distinguished from others which have one or more circular holes bored in them and others which are curiously bent at an angle. Such specimens are often carved with small unimportant ornament, not requiring development or printing. They as well as the present class have been spoken of as "wands of authority" and "sceptres"; some are considered to be arrow straighteners; others have been supposed to be "divining rods" or "rods of witchcraft"; whilst one of those discovered by M. Piette (others similar to it are known) has been regarded as a "lance thrower" or "propulsor" (such as modern primitive races use), having a notch at one end upon which the lance to be thrown is made to rest. The latest suggestion as to these notch-and-hook-bearing rods, is that they are large crochet hooks used in making nets. It has also been suggested that some of these carved rods were used as "fasteners" of the skins used as clothing.

I venture to suggest that the elaborately carved cylinder which we are considering and others bearing similar carvings, which only show up when a printing of them is taken, were used by the men who made them for this very same "printing" as an end in itself. The picture could be thus impressed on skins, birch bark, and other material. This race was thoroughly familiar with the use of paint formed by mixing grease with charcoal (to produce black), red ochre (to produce red), yellow ochre (to produce yellow), and some preparation of limestone or chalk (to produce white). Coloured pictures representing animals of the chase, coloured with red, yellow, white, and black and outlined by engraving, have been discovered on the rock walls of the caves used by them. Such pictures are found of relatively early as well as of late date within the post-Glacial Palæolithic period (see Chapter III). The rock picture of a single animal is usually from two to five feet long. People who could make those coloured designs and who could draw and compose so admirably as the author of the "Three Red Deer" would have desired to "roll off" and to possess printings of their favourite representations of animal life, whilst we must admit that their skill and ingenuity was assuredly equal to the task of so printing them. If this carving of the "Three Red Deer" were never printed it could not have been executed in the first place, nor seen and admired when completed. If even only half a dozen or a dozen impressions were taken from it for ornamenting the skins or other material used by a chief, or a wizard, or a woman, its production becomes intelligible. It is true that there is nothing known as to the use of such printing from a cylinder among existing primitive people, but it is known in very early times (4500 B.C.), since cylindrical seals were used by the Babylonians. Elaborately grooved blocks used for printing on cloth are known from Fiji and Samoa, and the mere practice of printing on to a flat surface is common enough among savage races in regard to the human hand, impressions or prints of which obtained by the use of a greasy pigment are found upon rocks or stones. Sometimes prints of the hand or fingers are taken in clay.

We must not, however, forget that the primary purpose of savage and primitive mankind in making images or engravings of animals is that of influencing the animals by witchcraft or magic, as has been urged by Reinach. From such magic-working drawings the art of savages has gradually developed just as religious figures and designs have been the initial motive of historic European art.

It seems in any case fairly certain that the artist who engraved our picture of the three deer on to the stag's antler must have worked from and copied a completed flat drawing, and probably printed it in some way on to the prepared antler before engraving its lines thereon and also checked the work, as he proceeded, by successive trial printings or "proofs" on to a flat surface. It is possible though it does not seem very probable, that the drawing was thus committed to perpetual invisibility on a cylindrical rod—for the purpose of exercising "magic" with that rod. It seems to me that the Cromagnard owner of the rod would have wished to see "what the picture really looked like," and so would have on some occasion and more than once have "printed it off" or as we say "unrolled it."

Leaving that question aside I have a few words to say as to the present attempted "completion" of the picture. My difficulty has been in realizing the suggestion of a free, graceful "bounding" action given by the pair of small hind legs which form all that remains of the smallest of the three deer. I have tried various poses of the calf indicated by these legs—bucking and jumping, and with fore legs closely bent to the horizontal or in a more open position. The fact is there is very little in existing drawings or photographs which can help us to a decision of the problem, "How did the prehistoric artist complete that exquisite little pair of hanging legs?" The problem is more obscure even than that of the pose of the arms of the Venus of Melos. One feels sure that the man who made this carving was an artist who must keep a certain rhythm and flow in the action and form of the three successive animals, and it is clear that he was a wonderful observer of the phases of the limbs in movement. It is, perhaps, a presumptuous thing to attempt on such a basis to recall the thought of a man who died twenty thousand years ago, but I set out to do so with the belief that there is a necessary figure determined by those hind legs.

Some years ago, as a step towards a solution of the problem, I published a "restoration" or "completion" of this picture in the "Field" (May 13th, 1911), and asked for criticisms and suggestions from the readers of that journal. I had no difficulty as to the completion of the biggest stag by drawing in his haunches and hind-legs, but the completion of the head and antlers of the smaller stag—and still more the calling into being of the entire calf as an inference from his or her suspended hind-feet and hoofs alone—were not easy tasks. I consulted many authorities and some instantaneous photographs, but I was not satisfied with the pose I finally suggested for the calf nor with the "points" assigned by my draughtsman to the antlers of the smaller stag. Some interesting suggestions were made in reply to my appeal by readers of the "Field." Those which seemed to me of conclusive weight and value were offered by Mr. Walter Winans, who combines the qualifications of a great observer of big game with those of a great artist. In the restoration now given in Fig. 5 I have profited by Mr. Walter Winans' criticism and have been especially glad to make use of the spirited sketch made by him for my benefit, and published in the "Field" of 1911, of a red-deer calf when hopping along with all the feet together, a movement known as "buck-jumping." "Of course," writes Mr. Winans, "this is quite different to the bronco-pony's action when trying to get rid of a rider. In the case of this kind she does not come down with a jar—but as she lands bends her knees and hocks simultaneously and then straightens them, also simultaneously, bounding in the air with bent back, tail curled tight on back, head thrown back, and ears forward; she never puts her fore-legs, either knee or fetlock, beyond her shoulder in this action." These words of Mr. Winans and his outline sketch of the buck-jumping calf precisely realize what the little hanging legs of the rubbed-out calf had been, as it were, urging my tired brain to recall and visualize. I am convinced that Mr. Winans' sketch gives the completion of the picture as drawn by the artist of the Lortet cavern, and satisfies the demand made by the gracefully suspended limbs shown in the incompletely preserved original. And so I have used it in my final restoration here given in Fig. 5.

The following letter by Mr. Winans, giving valuable comments on the Lortet picture, was published in the "Field," and will assist others in appreciating its significance: it enabled me to get the middle stag's antlers correctly drawn. I have omitted a few lines referring to defects in the original restoration—now corrected.

Sir,—As Sir Ray Lankester asks for criticism of this wonderful drawing of three deer, perhaps the following may be of interest. I have known deer all my life, and lived amongst them the last twelve years. I agree that the picture is wonderful—better than anything Landseer or Rosa Bonheur drew, because these latter were only artists: one can see by their pictures (full of faults as to attitudes and actions) that they knew nothing of deer. For instance, Landseer's stags were much too big in the body and their heads too small, and even the shape of their horns was conventional....

"The Lorthet drawings enable one to know all details about the three deer (looking at the original mutilated 'development'). First, the deer have 'got the wind' of an enemy, have come a long way, and are moving leisurely, the big stag, as usual, bringing up the rear and taking a last look round before the herd goes out of sight. The second is the younger stag who generally accompanies the big stag and acts as his sentinel when he is sleeping, a stag too small to give the big stag any jealousy as to his hinds. The third is undoubtedly a calf (Red deer are 'stags,' 'hinds,' and 'calves,' not 'does' and 'fawns'; the latter terms apply to Fallow deer and Roe-deer).

"The deer are typical Red deer, not Wapiti, except that the only tail showing (that of the middle deer) is the short Wapiti tail, not the longer tail of the Red deer, and the ears are shorter than those of any existing species of deer.

"The horns of the big stag are those of typical park Red deer, exactly like the Warnham Park big stag: brow, bay, and tray, with a bunch on top, and the horns are short and straight for their thickness.

"Now as to the short tail. I am trying, by crossing the Wapiti, Red deer, and Altai to get back to the original deer before the various species got separated, and my 'three-cross' deer show these very characteristics, as follows: Red deer or Warnham horns, short Wapiti tail, and the rather Roman nose which this 'development' print shows. The only difference is the short ears. Is it not possible that, as the artist is able to draw the horns in perspective and show the anatomy and proportions so well, that the ears are meant to be drawn fore-shortened?

"The stag's mouth is open because he is big and fat and is blowing (not roaring or bellowing). If it was the rutting season, when stags roar, the stag would be tucked up in the belly and have a tuft of hair hanging under the middle of it. He and the stag in front are moving in the real action (not the conventional action Rosa Bonheur and Landseer drew, but what the ancient Egyptians drew sometimes) of a slow, easy canter.... Now as to the middle stag's horns. I should give him, bearing in mind he is the small sentry stag, brow, tray, and three on top—a ten-pointer, the thin points showing in the original drawing indicating that he had thin horns—in fact, a three-year old.

"In a Scotch forest a ten-pointer is a comparatively old stag, but at Warnham and my place, where the feeding is good (and in my case there is hand feeding all the year round), a spike stag gets six points and can almost be a royal the next year.

"All this shows that the deer at the time this drawing was made must have had very good feeding and come to maturity quickly, like modern park deer. The big stag would never have allowed a ten-pointer in his herd if the latter had been an old stag.

"As to the action of the leading hind. I think she is a hind-calf by her legs, and is jumping with all four legs together, the way young deer do when playing, and, being young, is paying no attention to the danger behind, but is full of life, like a horse playing about when he is fresh. One often sees the calves of a herd playing like this if the herd is moving along steadily....

"From the position of the hind legs of the little calf I judge that she is jumping with all four legs together (the jump from which the expression 'buck jumping' comes); her tail would be curled up tight over her back like a pug dog carries it, only without the curl, and her ears pricked forward. The piece of horn broken off would show the rest of the hinds and calves, led by an old 'yeld' (i.e., barren) hind, who would be leading the herd up wind with her nose and ears forward to 'get the wind' of any danger ahead.

"The day is a hot one in the middle of August, shown by the big stag blowing and his being with the hinds, instead of with other stags by themselves, and by his not having 'run' yet, though his horns are clear of velvet. He is most likely the stag on whose horn this is engraved. The length of the deer's feet shows that they live on ground which is soft and not many stones about to wear down their toes.

"Maybe the fish indicate that the deer are crossing a shallow ford, and the salmon are getting frightened and jumping. The right-hand-most fish is just in the attitude of a hooked salmon trying to leap clear of the fly....

"The picture was most likely first drawn on some flat flexible surface, skin or bark, in a sticky medium, and then transferred to the horn by rolling it round the horn and then rubbing it. This would give a transfer, which would guide the subsequent engraving, otherwise it would be very difficult to engrave direct on the horn, and mistakes could not easily be corrected.

"Walter Winans

"Surrenden Park, Pluckley, Kent

With regard to the six fishes in the picture of "The Three Red Deer," I think that there can be little doubt that they are put in in the same spirit of exuberance which induced early Italian masters to introduce a cherub wherever a space for him could be found. The fish represented are the same in each case, and are undeniably salmonids. Presumably they are drawn on a larger scale than the deer. Their markings and the form of the head are deserving of some criticism and comment by those who are familiar with fish as seen by the fisherman. Probably the artist's friends at Lourdes captured fish in those days by spearing them with serrated bone-headed fish spears or harpoons (Fig. 3). No fish hooks of bone have been found in the cave of Lortet or in others of like age, although needles and whistles of bone and other useful little instruments, as well as serrated spear heads and harpoons have been obtained in several of them.

The tool used by the prehistoric man in engraving the cylinder of stag's antler was undoubtedly a suitable chipped-out piece of flint—a flint graving tool, in fact a "burin," such as are abundant in these caves.

Fig. 6.—Fragment of a roughly-painted vase of the Dipylon age (circa 800 B.C.) from Tiryns, figured by Schliemann and cited by Hörnes in his "History of Pictorial Art in Europe." Compare the fish between the horse's legs with the fish in the Lortet picture of the Three Deer; also note the lozenge-shaped designs (similar to the pair above the big stag in the Lortet picture) near the fish and near the man's head (d); and, further, the swastika (s).

Attention has been drawn by Hörnes in his "History of Pictorial Art in Europe" to the resemblance of the Lortet picture to a fragment of a roughly painted vase of the Dipylon age (circa 800 B.C.) found at Tiryns and figured by Schliemann in his account of excavations made at that ancient Mykenæan fortress of the Peloponese. The fragment (Fig. 6) shows very roughly drawn figures of a man and of a horse. Between the fore and hind legs of the horse a large elaborately ornate fish is represented, reminding us of the fishes between the deer's legs in the Lortet picture. Two other similar fragments of pottery, showing a fish in this position, are recorded by Schliemann. The drawing is conventional and careless. It is of a debased decorative character, and is very far removed from the careful nature-true work of the Lortet cave-man. It is not possible to trace by any known line of transmission a connection between the engraving executed 20,000 years ago in the caves of the Pyrénées and the figures rapidly knocked off in black paint on the Tiryns vase some 17,000 years later by the local dealers in cheap pottery. Yet we cannot avoid the suggestion that there is some connection between the two designs. For the Tiryns painting shows not only the curious upright fish between the horse's legs, but also diamond-shaped figures—one marked d in Fig. 6, another near the fish's tail, and another between the man's feet—closely resembling the pair of diamond-shaped figures engraved above the neck of the big stag in the Lortet picture (see Figs. 4 and 5). As we do not know what these diamond-shaped figures or "lozenges" are intended to signify in either case, we do not get, at present, beyond the bald fact of their coincidence. The Tiryns painting also shows (at s in Fig. 6) a "swastika" (see Chapter XVII), and below the man's arm a carelessly drawn bit of the ancient wave-fret or key-pattern. It is, of course, possible that the tradition of an ancient design—even dating so far back in origin as many thousands of years—may be preserved in the use made in the Tiryns decoration of the fish and the diamond-shaped lozenges, though associated with the swastika and the bit of wave-fret which are probably of later origin and are not known in the decorative work of the cave-men. The Mykenæan decorative assimilation of geese to the ship's barnacle exercised its influence over three thousand years and led to the mediæval belief in the hatching of young geese from barnacles attached to floating timber, and even from the buds of trees (see my "Diversions of a Naturalist": Methuen, 1915). Nevertheless it must not be supposed that the connection of the Lortet engraving and the vase-painting of Tiryns is probable or more than a very remote possibility. The gap in time is too vast, and our present ignorance of what took place in that interval too complete, to warrant us in regarding the resemblance as more than a coincidence.

FOOTNOTES:

[1] "L'Age du Renne," a posthumous work, with one hundred coloured quarto plates of objects in the Piette collection, is published by Masson, of Paris, and gives the complete list of Piette's numerous earlier papers, issued as his excavations proceeded.

[2] Seven years ago the ape-like lower jaw and thick walled brain-case called "Eoanthropus" were discovered in a sparse gravel near Lewes in Sussex. It is probably of older date than either the Neander men or the Heidelberg men. See on this subject the chapters on "The Missing Link" in my "Diversions of a Naturalist" (1915) and those on "The Most Ancient Men" and "The Cave-men's Skulls" in "Science from an Easy Chair. First Series" (1910).

CHAPTER II

PORTRAITS OF MAMMOTHS BY MEN WHO SAW THEM

SOME fifty-five years ago pieces of reindeer's antler were discovered in the cave known as "La Madeleine" in the Dordogne (a department of France some eighty miles east of Bordeaux), upon which were engraved the outlines of various animals such as reindeer and horses. They and the bone spear-heads and needles, and the flint knives found with them, were the first revelation to later man of the existence of the prehistoric cave-men. Among the carvings was a piece of ivory which excited the profoundest interest. Partly hidden by a confused mass of scratches it showed the well-drawn outline of the great extinct elephant, thus scratched or "engraved" on a bit of its own tusk (Fig. 7). The engraving was barely 5 in. long, and has been reproduced in many books. The specimen is now in Paris, and was for long the only known representation of the Mammoth by the ancient men who lived with it in Western Europe.

Fig. 7.—Engraving of a mammoth drawn upon a piece of mammoth's ivory, found in the cave of La Madeleine in the Dordogne, in 1864. The specimen is in the Museum of Natural History, Paris. The engraving is here represented of the actual size.

During the last fifteen years, however, our knowledge of the works of art executed by these ancient men has increased to an extraordinary extent, chiefly owing to the energy and skill of the French explorers of the caverns in the south central region of that country. As long ago as 1879 a little girl, the daughter of Señor Sautuolo—a proud woman she should be if alive to-day—when visiting the cavern of Altamira, near Santander, in the north of

Spain, with her father, drew his attention to a number of "pictures of animals," painted on the rocky vault or roof of the cave. At first no one believed that these pictures were more than a few hundred years old, whilst some held them to be modern and made with fraudulent purpose. In 1887 Piette, the distinguished French investigator of the remains of human work in the caverns of the French Pyrénées (whose great illustrated book of carved and engraved portions of reindeer antler, ivory, and stones discovered by his excavations, is a classic), declared that in his opinion the pictures of the Altamira cave were of the same age as the bone and ivory carvings of the Madeleine cave—that is to say, dated from what "prehistorians" call the later Palæolithic age, an age when the mammoth, the bison, the cave lion, and the reindeer still existed in Western Europe, and when the British Isles were not yet separated by sea from the Continent. The age indicated is probably from 25,000 to 50,000 years ago. Still, the opinion prevailed that the "wall-drawings" and "roof-drawing" of the Altamira cave were either mediæval or modern until the French explorers discovered wall-paintings in some of the caves of the Dordogne. Then they proceeded to a careful investigation of the Altamira cave, and discovered conclusive evidence of the great age of the paintings by the removal of some of the undisturbed deposit in the cave, in which were found flint implements and small engravings on bone, proving the deposit to be of the late Palæolithic age. When this deposit was removed, pictures of animals, partly engraved and partly completed in colour (black, red, yellow, and white), were found on the wall of the cave previously covered up by the deposit. M. Cartailhac, who had been a leading opponent of the view that the Altamira wall-pictures were very ancient, now renounced his former position and became an enthusiastic investigator and exponent of these pictures. M. Breuil, who had discovered wall-pictures, including those of the mammoth, in French caves, and had been met by disbelief and even suspicion, now received due recognition, and joined Cartailhac in preparing a complete account of the wall and roof pictures of the Altamira cave. The Prince of Monaco, who had carried out, with the aid of French experts, an investigation of the caves on his property at Mentone, on the Mediterranean "Riviera," undertook the expense of producing a splendid volume, giving coloured reproductions of the Altamira pictures. To him the world is indebted, not only for most important discoveries of human skeletons and objects of human workmanship in the caves of Mentone (there are no wall-pictures there), but for the publication in illustrated form of the Mentone discoveries and of those obtained in the Altamira cave. He has not rested at this stage of accomplishment, but has produced at his own expense large volumes by MM. Breuil, Capitan, and Peyrony, illustrating and describing the discoveries made by them of wall-paintings and engravings of animals in the cave known as the "Font de Gaume," in the Dordogne. The Prince has also published a volume, by MM. Breuil, de Rio, and Sierra, reproducing the drawings found in a whole series of caves and rock-shelters in various parts of the Spanish peninsula, where the rock-painting race seems to have persisted to a somewhat later period and to have painted, more frequently, pictures of human beings as well as of animals. These, whilst less artistic and truthful than those of the North Spanish and South French area, yet have surpassing interest, since they have special similarity to ancient rock-paintings found in North Africa and to the rock-paintings of the Bushmen of South Africa.

The Prince of Monaco has finally established the great study in which he has played so valuable a part by founding in Paris an "Institute of Human Palæontology"; that is, "of the study of prehistoric man," which he has endowed with a magnificent building, comprising laboratories and residences for professors, together with funds to pay for its maintenance and the proper publication of results. This he has done in addition to founding entirely at his own expense a similarly complete Institute for the study of "oceanography"—the study of the living contents and history of the great seas.

The illustrations in this chapter are (with the exception of Fig. 7) copies, greatly reduced in size, of faithful representations of the great hairy elephant or mammoth which still survived in southern France in the days when the caves were occupied and decorated by men. I am indebted to the valuable little book "Repertoire de l'Art Quatermaire," by M. Salomon Reinach, for these outlines carefully drawn by him from various large illustrations by the use of a tracing and reducing instrument. In the next chapter I have given examples from the same source of similar drawings of other animals.

There are five kinds of artistic work of Palæolithic age found in the caverns of France and Spain; namely (1) small solid carvings (complete all round) in bone, ivory, or stone; (2) small engravings in sunk outline on similar material, rarely with relief of the outlined figure; (3) large stone statues, 2 ft. to 6 ft. across, in high relief, with complete modelling of the visible surface; (4) rock engravings and paintings on the walls and roofs of caverns or rock shelters, often partly outlined by engraving and scraping of the surface, and then completed in black or red paint or in several colours (black, red, yellow, white); they are of large size, from 2 to 5 ft. in cross measurement; (5) models in clay, one side only shown, the other resting on rock; a few incomplete clay models of this nature representing the bison of about 2 ft. in

length, have recently been discovered in one of the French caverns, and are the only examples of modelling in clay by the Palæolithic men yet discovered.

Fig. 8.—Outline engravings of mammoths on the wall of the cavern known as the "Font de Gaume," near Eyzies (Dordogne). Each figure is about 2 ft. long.

Our figures of the mammoth are (excepting Fig. 7) all of the fourth class—namely, rock-paintings in one colour (black or red) partly engraved and scraped. The originals are from 1-1/2 ft. to 2-1/2 ft. long. The mammoths given in Fig. 8 are carefully copied from engravings discovered, reproduced, and described by M. Breuil and his fellow-workers. They are on the walls of the cavern known as the "Font de Gaume," in the commune of Tayac in the Dordogne. Those copied in Fig. 9 and Fig. 10, A, were discovered on the walls of the cave of Les Combarelles in the same district.

Fig. 9.—Similar engravings from the neighbouring cave of Combarelles. The lower figure is an enlargement of the smaller of the two above it.

Fig. 10, B, is from a cave at Bernifal, near les Eyzies, in the Dordogne, and shows a mammoth enclosed in a triangular design, which is believed to represent a trap, or else a cage. Such triangular figures with upright and also bent supports are found in various degrees of elaboration on both small and large engravings of this period, and are generally accepted as representing huts or enclosures supported by wooden poles. They are called "tectiforms" by the French explorers.

Fig. 10.—A, similar engraving from the cave of Combarelles. B, Mammoth enclosed by plank-like structure—supposed to be either a cage or a trap. (Called tectiform structures, and often seen in these wall engravings.) From the cave of Bernifal, five miles from Eyzies.

The bones and teeth of the mammoth are very common in the river gravels and clays of Western Europe and England, and a complete skull, with its tusks, dug up at Ilford, in the east of London, is in the Natural History Museum. Frozen carcasses of this animal are found in Northern Siberia, and two showing much of the skin and hair are in the museum of Petrograd. There is no tradition or knowledge of the mammoth among living races of men. The natives of Siberia, who have from time immemorial done a large trade in the ivory, regard the tusks as "horns," and have stories about the ghosts of the mammoth, but no tradition of it as a living beast. The mammoth was closer to the Indian elephant of to-day than to the African one. It had, as these drawings show, a pelt of long hair. Indian elephants from upland regions often have a good deal of hair all over the body: and the newborn young of both the Indian and African elephant has a complete coat of hair. The drawings here reproduced are not only of thrilling interest because they are the work of remotely ancient men who lived with and observed mammoths in the south of France, but also because they show an extraordinary skill in "sketching"—in giving the essential lines of the creature portrayed and in reproducing the artist's "impression." These artists were "impressionists"—the earliest and most sincere—without self-consciousness or other purpose than that of making line and colour truly register and indicate their vivid impressions. It is interesting to note that (as in other works of art showing true artistic gift) actual error in drawing (for instance, in the size and shape of the eye and the placing of the two tusks on the same side of the trunk—possibly due to the unfinished state of the drawing) sometimes accompanies the most penetrating observation and skilful delineation of the characteristic form and pose of the animal. Probably mammoths were getting rare in the south of France when these drawings were made, and were not so familiar in all their details to the artist as were bison, horse, and deer.

CHAPTER III

THE ART OF PREHISTORIC MEN

THE works of art produced by the cave-men are, as we have already seen, of five kinds or classes—(1) All-round small statuettes, or "high-relief" carvings, in ivory, bone, or stone (examples of which are shown in Figs. 14, 25, 26, 27, 28 of the present chapter); (2) small engravings on bits of ivory, deer's antler, bone, or stone (examples are shown in Figs. 15, 16, 20, and 24); (3) large statues, hewn in rock, and left in place; (4) drawings of large size—two to five feet in diameter (partly engraved and partly coloured) on the rocky walls and vaults of limestone caverns (shown in Figs. 11, 12, 13, 17, 18, 19, 23, as well as in the figures of mammoths in the last chapter); (5) models (high relief) worked in clay. I give reproductions in the present chapter of several samples of this art, showing how skilfully these men of 50,000 years ago could portray a variety of animals.

Who were these men, and why did they make these remarkable carvings and drawings? First, as to their age. We now know of a long succession of human inhabitants of this part of the world, namely, Western Europe. The earliest reach back to an antiquity never dreamed of fifty years ago. We cannot fix with any certainty the number of thousands, or hundreds of thousands, of years which is represented by this succession, but we can place the different periods in order, one later than the other, each distinguished chiefly by the character of the workmanship belonging to it, though in a few instances we have also the actual limb-bones, skulls, and jaw-bones of the men themselves, which differ in different periods. It is practically certain that these prehistoric successive periods of humanity do not represent the steps of growth and change of one single race belonging to this part of the world, but that successive races have arrived on the scene of Western Europe from other parts, and it is usually very difficult even to guess where they came from and where they went to!

It is convenient to divide the human epoch, the time which has elapsed since man definitely took shape as man—characterized by his large brain, small teeth, upright carriage, and large opposable thumb and still larger and more peculiar non-opposable great toe—into the historic and the prehistoric sections. In this part of the world (Europe) the first use of metals (first of all copper, then bronze, and then iron), as the material for the fabrication of implements and tools of all kinds, occurs just on the line between the historic and the prehistoric sections; that is to say, between those times of which we know something by tradition and writing, and those earlier times of which we have no record and no tradition, but concerning which we have to make out what we can by searching the refuse heaps and ruins of man's dwelling-places and carefully collecting such of his "works" as have not utterly perished, whilst noting which lie deeper in the ground, which above and which below the others.

Practically the men of the prehistoric ages in Europe had not the use of metals (though our quasi-historical records go back to a less remote time in many parts of Europe than they do in Greece, Assyria, and Egypt). The prehistoric peoples are spoken of as the men of the Stone Age, because they used stone, chiefly flint, as many savage races do to-day, as the material from which they fabricated by means of deftly struck blows all sorts of implements. Undoubtedly they also, by aid of stone knives, saws and planes, made weapons and other implements of wood and of the horns, bones, and teeth of animals. But these latter substances are perishable, and have only been preserved from decay under special circumstances, such as their inclusion in the deposits on the floors of caverns.

The Stone Age is itself readily and obviously divisible into two periods. The latter is a comparatively very short and recent period, when great skill in chipping flints and other stones was attained, and the implements so shaped were often rubbed on large stones of very hard material (siliceous grit), so as to polish their surfaces. This is the "Neolithic," or later Stone, period, and extends back in Europe certainly to 7000 B.C., and probably a few thousand years further. Passing further back than this, we leave what are called "recent" deposits, and come to those associated with great changes of the earth's surface. We enter upon "geological" time, and vastly changed climatic and geographical conditions. We are in the older Stone period, called the "Palæolithic period." It is not really comparable to the "Neolithic," since it comprises many successive ages of man, and, although called the "Palæolithic" or "ancient Stone" period, has no unity, but, whilst readily divisible into several sub-periods or epochs of comparatively late date, stretches back into immense geologic antiquity indicated by flint implements of special and diverse types, which are found in definitely ascertained geologic horizons.

The Pleistocene strata—the latest of the geologists' list—are the river gravels of existing river valleys, the deposits in many caves, and the sands and clays piled up by ice action during the repeated glacial extensions or epochs of glaciation which alternated with milder climate for many thousands of years over north and middle Europe. It is identical with the Palæolithic period, which, however, probably extends beyond it into the Pliocene and even further back. In the later deposits of the Pleistocene, which necessarily have been less frequently disturbed and re-deposited than the older ones, we find more numerous remains of man's handwork, and in less disturbed order of succession, than in the older deposits. Lately we have obtained in East Anglia beautifully-worked flint implements—the rostro-carinate, or eagle's beaks—from below shelly marine deposits—the Red Crag of Suffolk and the Norwich Crag—the oldest beds of the Pleistocene. They were made by men who lived in the Pliocene period, and carry the ancient Stone period of man back to a much earlier period than was admitted nine years ago.

The Pleistocene series or "system " of strata—also called the "Quaternary" to mark its distinction from the underlying long series of "Tertiary" strata—does not comprise the actual surface-deposits in which the remains of Neolithic man are found. It is usual, though perhaps not altogether logical, to separate these as "Recent" and to begin the long enumeration of "geologic" strata after a certain interval when the relative levels of land and sea and the depth of river-valleys were not precisely what they are to-day, and the human inhabitants of Western Europe were hunters using rough unpolished flint implements—in fact, when the "Palæolithic" period of human culture had not given place to the "Neolithic," which was after some ten thousand years itself to be superseded by the age of metals. "Prehistorians," the students of prehistoric man—divide the Pleistocene series of deposits with a view to a systematic conception of the successive changes of man and his surroundings during the period occupied by their deposition, into an upper, a middle and a lower group—and further have distinguished certain successive "horizons" in these groups—characterized by the remains of man and animals which they contain. They are exhibited in the tabular statement here given in the ascertained order of their succession, and are represented in the southern part of Britain as well as in France.

HORIZONS OR EPOCHS OF THE PLEISTOCENE OR QUATERNARY SYSTEM

A. Upper Pleistocene (post-glacial; also called epoch of the Reindeer).

1. The Azilian: (Elapho-Tarandian of Piette) nearest to the Neolithic section of the Recent Period and more or less transitional to that period; named after the cavern of the Mas d'Azil in the department of the Ariège. The Reindeer had largely given place to the great Red Deer (Cervus elephus).

2. The Magdelenian: named after the cave of La Madeleine in the Dordogne.

3. The Solutrian: after Solutré near Macon.

4. The Aurignacian: after the grotto of Aurignac in the Haute Garonne.

B. Middle Pleistocene (period of the last great extension of glaciers).

1. The Moustierian: so named after the cave of Le Moustier in Dordogne; the epoch of the Neander men. Also called the "epoch of the Mammoth," whilst the upper Pleistocene is called the epoch of the Reindeer, though the Mammoth still survived then in reduced numbers.

C. Lower Pleistocene (inter-glacial and early glacial, also called period of the Hippopotamus and of Elephas antiquus and Rhinoceros Merckii).

1. The Chellian: named after Chelles on the upper Seine, river gravels and sands earlier than the Moustierian. Large tongue-shaped flint implements, flaked on both surfaces—the later and better-finished classed as "Acheulæan," after St. Acheul, near Amiens.

2, 3, 4 ... various fluviatile and lacustrine gravels, sands and clays divisible into separate successive horizons, as well as marine deposits, some of glacial origin—including the mid-glacial gravel, the boulder clays and shelly Red Crag and Norwich Crag (but not the underlying "Coralline" Crag, which must be classed with the Pliocene). The relations of the marine deposits to the older river-gravels and fresh-water deposits, and to the earlier periods of glacial extension indicated by the glacial moraines of central Europe, have not been, as yet, satisfactorily determined.

The amount of the sedimentary deposits of the earth's crust belonging to the Pleistocene or Quaternary Period—about 250 feet in thickness—is exceedingly small, and represents a surprisingly short space of time as compared with that indicated by the vast thickness of underlying deposits. It has nevertheless been possible to study and classify the "horizons" of this latest very short period minutely because the deposits are easily excavated, and having been more recently "laid down" have not suffered so much subsequent breaking up and destruction as have the older strata; and further, because they embed at certain levels and in favourable situations an abundance of well-preserved bones and teeth of animals and the implements and carvings in stone and bone made by man. It is worth while to look at this matter a little more exactly.

The total thickness of sedimentary deposits—that is, deposit laid down by the action of water on the earth's surface, and now estimated by the measurement of strata lying one over the other in various parts of the globe—tilted and exposed to view so that we can trace out their order of super-position—is about 130,000 feet. The lower half of this huge deposit contains no fossilized remains of the living things which were present in the waters which laid it down; they were soft, probably shell-less and boneless, and so no fossilized trace of them is preserved. Thus we divide the sedimentary crust into 65,000 feet of "archaic" non-fossiliferous deposit, and an overlying 65,000 feet of fossil-containing deposits.

The earliest remains of living things known are not very different from marine creatures of to-day; they are the strange shrimp-like Trilobites and the Lingula-shells found in the lower Cambrian rocks of Wales. Over them lie 65,000 feet of sedimentary deposit teaming with fossils—the petrified remains of animals and plants. The Trilobites and the Lingulas must have had a long series of ancestors leading up to them from the simplest beginnings of life—for they are highly organized creatures. But no trace of those ancestors is preserved in the 65,000 feet of sedimentary rock underlying the earliest fossils.

This great basal mass of non-fossiliferous deposit is called "the Archæan series." The 65,000 feet of deposit above it are divided by geologists into three very unequal series. The first and lowest is the Primary or Palæozoic series, occupying the enormous thickness of 52,000 feet; above these we have the Secondary or Mesozoic series of 10,000 feet, and lastly, bringing us to recent time, we have the Tertiary or Cainozoic of only 3000 feet. These three series amount in all to 65,000 feet. The Palæozoic series is more than five times as thick as the Mesozoic, and these two taken together are twenty times the thickness of the Tertiary. Each series is divided by geologists into a series of systems, distinguished by the fossils they contain, which, on the whole, indicate animals of a higher degree of evolution as we ascend the series.

The Palæozoic series include the vast thicknesses of the Cambrian, the Ordovician, the Silurian, Devonian, Carboniferous and Permian systems. The first "trilobite" is found in the lowest Cambrian rocks, and the last or most recent existed in the Permian period—after 50,000 feet of rock had been deposited. None are known of later age. The first fossil remains of a vertebrate are found in the uppermost beds of the Silurian—in "beds" (that is to say, stratified rocks) which are just half-way in position so far as the measurable thickness of the deposits are concerned, between the earliest Cambrian fossils and the sediments of the present day. To put it another way, 34,000 feet of fossiliferous rock precede the stratum (upper Silurian) in which the earliest remains of vertebrates are found. These first vertebrates to appear (others soft and destructible preceded them) are fishes—a group which, apart from this fact, are shown by their structure to present the ancestral form of all the vertebrate classes. In later Palæozoic beds we find the remains of four-legged creatures like our living newts and salamanders. The Secondary or Mesozoic series is divided into the Triassic, Jurassic and Cretaceous systems. It ends with the familiar chalk deposit of this part of the world, and is often called the age of Reptiles, because large reptiles abounded in this period. The Tertiary or Cainozoic series are divided into the Eocene, Oligocene, Miocene, Pliocene and Pleistocene systems. The huge reptiles disappear and their place is taken by an endless variety of warm-blooded, hairy animals—the Mammals—small at first, but in later beds often of great size. As we pass upwards from the Eocene we can trace the ancestry of our living Mammals such as the horse, rhinoceros, pig and elephant in successive forms. Complete skeletons are preserved in the rocks and show a gradual transition from the more primitive Eocene kinds—through Miocene and Pliocene modifications—until in the Pleistocene strata many of the species now inhabiting the earth's surface are found. A number of horizons, characterized by the special mammalian and other animal remains preserved in them, are distinguished by geologists in each of the "systems" of sands, clays and harder beds known as Eocene, Oligocene, Miocene and Pliocene. At last we arrive at the latest or most recent 250 feet of deposit, consisting of sand, clay and gravel. This is called "Pleistocene." It is only a very small fraction (1/260^th) of the thickness of the whole fossil-bearing sedimentary crust of the earth—about the proportion of the thickness of a common paving-stone to the whole height of Shakespeare's cliff at Dover. This Pleistocene or post-glacial Tertiary—often now called Quaternary—has been so carefully examined that we divide it as shown on page 39 into upper, middle and lower, and each of these divisions into successive horizons (only a few feet thick) characterized by the remains of different species of animals and often by the differing implements and carvings as well as the bones of successive races of men.

When we are concerned with written history, ancient Egypt seems to be of vast and almost appalling antiquity; on the other hand, if we study the cave-men, ancient Egypt becomes relatively modern, and the first cold period and extension of glaciers, which 500,000 years ago marked the passage from Pliocene to Pleistocene, becomes our familiar example of something belonging to the remote past—beyond or below which we rarely let our thoughts wander. That is a natural result of concentration on a special study. But it has had the curious result, in many cases, of making students of ancient man unwilling to admit the discovery of evidences of the existence of man at an earlier date than that which belongs to the deposits and remains to which their life-long studies have been confined and upon which their thought is concentrated. The last 500,000 years of the earth's vicissitudes, which resulted in the 250 feet of "Pleistocene" deposit and the marvellous treasures of early humanity embedded in them, form but a trivial postscript to the great geological record which precedes it.

Fig. 11.—Horse (wall engraving), cave of Marsoulas, Haute Garonne. The drawing suggests the Southern less heavy breed as compared with Figs. 12 and 13.

Fig. 12.—Horse (wall engraving) outlined in black, cave of Niaux (Ariège).

Fig. 13.—Horses: A, wall engraving (cave of Hornos de la Péna). B, wall engraving from cavern of Combarelles. C, engraved on reindeer antler (Mas d'Azil). Note the halter in A and in C; also note the heavy head and face of B like that of Prejalvski's horse.

No estimate can be made of the time represented by the 65,000 feet of fossiliferous strata known to us and the same thickness of non-fossiliferous deposit which precedes them. There are no facts known upon which a calculation of the related lapse of time can be based. But most geologists would agree that whilst we have good ground for assigning half a million years to the formation of the Pleistocene strata, it is not an unreasonable supposition that the period required for the formation of the fossiliferous rocks which precede them in time, is not less and probably more than five hundred million years.

Fig. 14.—Drawing (of the actual size of the original) of a flat carving in shoulder-bone of a horse's head, showing twisted rope-bridle and trappings. a appears to represent a flat ornamented band of wood or skin connecting the muzzling rope b with other pieces c and d. This specimen is from the cave of St. Michel d'Arudy, and is of the Reindeer period. This, and others like it are in the same museum of St. Germain.

Fig. 15.—Drawing (of the actual size of the original) of a fully rounded carving in reindeer's antler of the head of a neighing horse. The head resembles that of the Mongolian horse. This is one of the most artistic of the cave-men's carvings yet discovered. It is of the Palæolithic age (early Reindeer period), probably not less than 50,000 years old. It was found in the cavern of Mas d'Azil, Ariège, France, and is now in the museum of St. Germain.

The pictures and carvings with which we are for the moment concerned all belong to the later Pleistocene or Reindeer epoch. None have been found in the middle and earlier Pleistocene, though finely-chipped flints of several successive types are found in those earlier beds. So that it is clear that many successive ages of man had elapsed in Western Europe before these pictures—immensely ancient as they are—were executed. The men who made these works of art had ages of humanity, tradition, and culture (of a kind) behind them. Yet they were themselves tens of thousands of years earlier than the ancient Egyptians!

Fig. 16.—Reindeer engraving on schist, small size (cavern of Laugerie basse).

Fig. 17.—Rhinoceros in red outline (2-1/2 feet long), drawn on the wall of the cavern of Font de Gaume.

Our illustrations show a variety of drawings and carvings. It appears probable that the primitive intention of ancient man in depicting animals was "to work magic" on those which he hunted. This is the case at the present day among many "savage" races. The drawings of bisons in Fig. 19 are from the walls of the cavern of Font de Gaume, in the Dordogne, and are about 5 ft. long, partly engraved and scraped, partly outlined in black, and coloured. The body is often coloured in red, white and black, so as to give a true representation of the masses of hair and surface contours. A specially well preserved painting of this kind—from the cavern of Altamira—is shown in Fig. 18, where the colours of the original—black, red, and brown, and white are indicated by the varied shading. These drawings, like those of the mammoths figured in the last chapter, are found in the recesses of caverns where no daylight reaches them, and must have been executed and viewed by aid of torch or lamp-light. They probably were exhibited as part of a ceremony connected with witchcraft and magic. These, like the mammoths and all the specimens figured here, were executed in the Reindeer, or later Pleistocene period. The exact "horizon" of each is, as a rule, well ascertained, but there is uncertainty as to whether some specimens should be attributed to the Aurignacian or to the Magdalenian horizon—and as to whether work by men of the Magdalenian race is not in some cases associated in the cave deposits with that by the earlier negroid Aurignacians.

Fig. 18.—Bison from the roof of the cavern of Altamira: engraved, and also painted in three colours (5 feet long).

Fig. 19.—Bison: wall engravings (5 feet long) filled in with colour (Font de Gaume).

Fig. 20.—Bear: engraved on stalagmite, from the cave of Teyjat near Eyzies. (Small size.)

Fig. 21.—Bear, engraved on stone, Massol (Ariège).

Fig. 22.—Wolf, engraved on wall of the cave of Combarelles.

Fig. 23.—Wall engraving of a Cave Lion (Combarelles).

The horses shown are from various caves. Fig. 12 is drawn in black on the wall of a cave at Niaux (Ariège), and Fig. 11 is a similar drawing from a cave in the Haute Garonne. Both are remarkable for the exact representation of natural poses of the horse. Figs. 13, A and B, are also from the walls of caves. The latter is remarkable for the large head, short mane, and thick muzzle, which closely correspond with the same parts in the existing wild horse of the Gobi desert in Tartary (to be seen alive in the Zoological Gardens in London). The horse drawn in Fig. 11 seems to belong to a distinct race, suggesting the Southern "Arab" horse rather than the heavier and more clumsy horse of the Gobi desert. Fig. 13, C, is engraved of the size here given, on a piece of reindeer's antler. It is remarkable for the halter-like ring around the muzzle. A similar cord or rope is seen in Fig. 12 and in Fig. 13, A.

Fig. 24.—Goose: small engraving on reindeer antler (Gourdan).

The most remarkable horses' heads obtained are those drawn (of the actual size of the carvings) in Figs. 14 and 15. Fig. 14 is from the cave of St. Michael d'Arudy, engraved on a flat piece of shoulder-bone. It shows what can only be interpreted as some kind of "halter," made apparently of twisted rope (b, c, d), disposed about the animal's head, whilst a broad, flat piece ornamented with angular marks is attached at the regions marked "a." This and other drawings similar to Fig. 13, C (of which there are many), go far to prove that these early men had mastered the horse and put a kind of bridle on his head. Fig. 15 is a solid all-round carving in reindeer's antler from the cave of Mas d'Azil, Ariège (France). The original is of this size, and is supposed to be one of the oldest and yet is the most artistic yet discovered, and worthy to compare with the horses of the Parthenon.

In Fig. 20 we have a wonderful outline of a bear engraved on a piece of stone, from the cave of Teyjat, in the Dordogne; Fig. 22, the head of a wolf on the wall of the cave of Combarelles, Dordogne; Fig. 23, lion (mane-less), engraved on the wall of the same cave; Fig. 21, small bear, engraved on a pebble; Fig. 24, a duck engraved on a piece of reindeer's antler (Gourdan, Haute Garonne); Fig. 17, the square-mouthed, two-horned rhinoceros, drawn in red (ochre) outline on the wall of the cavern of the Font de Gaume. This drawing is 2-1/2 ft. long. In successful characterization the bear (Fig. 20), the wolf (Fig. 22), and the feline (Fig. 23) far surpass any of the attempts at animal drawing made by modern savages, such as the Bushmen of South Africa, Californian Indians, and Australian black fellows.

Fig. 25.—Female figure carved in oolitic limestone from Willendorf near Krems, Lower Austria (1908). Half the size (linear) of the original.

Fig. 27 is an outline sketch of a rock-carved statue, 18 in. high, proved by the kind of flint implements found with it to be of Aurignacian age. It was discovered on a rubble-covered face of a rock-cliff at Laussel, in the Dordogne, by M. Lalanne. The woman holds a bovine horn in her right hand. The face is obliterated by "weathering." Four other human statues were found in the same place, one a male, much broken, but obviously standing in the position taken by (Fig. 28) a man throwing a spear or drawing a bow. [3] Near these were found a frieze of life-sized horses carved in high relief on the rock. These are the only statues of any size, executed by the Reindeer men, yet discovered.

Fig. 26.—Drawing (of the actual size of the original) of an ivory carving (fully rounded) of a female head. The specimen was found in the cavern of Brassempouy, in the Landes. It is of the earliest Reindeer period, and the arrangement of the hair or cap is remarkable.

The representations of men are rare among these earliest works of art, and less successfully carried out than those of animals. But several small statuettes of women in bone, ivory, and stone of the early Aurignacian horizon are known. They suggest, by their form of body, affinity with the Bushmen race of to-day (Fig. 25). The all-round carving of a female head (Fig. 26) also suggests Ethiopian affinities in the dressing of the hair. Some regard this hair-like head-dress as a cap. Here and there badly executed outline engravings of men, some apparently wearing masks, have been discovered.

The fact that the "Reindeer men" were skilful in devising decorative design—not representing actual natural objects—is shown by the carving drawn in Fig. 29 and in many others like it.

Fig. 27.—Seated figure of a woman holding a bovine horn in the right hand; high relief carved on a limestone rock; about 18 inches high. Discovered at Laussel (Dordogne) in a rock-shelter in 1911, by M. Lalanne.

Fig. 28.—Male figure represented in the act of drawing a bow or throwing a spear. Carved on limestone rock; about 16 inches high. Discovered by M. Lalanne with that drawn in Fig. 27.

The later horizons of the Reindeer period or Upper Pleistocene yield some beautiful outline engravings of red deer and reindeer (Fig. 16) on antler-bone, as well as of other animals. One celebrated carving I have described in the first chapter of this book. It is now regarded as probable that whilst the art of the Aurignacians persisted and developed in the South of France and North-West of Spain until and during the time of the Magdalenian horizon, yet a distinct race, with a different style of art, spread through South-East Spain and also from Italy into that region, and affected injuriously the "naturalistic" Aurignacian art, and superseded it in Azilian and Neolithic times. We find late drawings (Azilian age?) in some of the east Spanish caves of a very much simplified character, small human figures armed with bow and arrow, and others reduced to geometric or mere symbolic lines derived from human and animal form (see Fig. 52, p. 206). The latest studies of Breuil on this subject tend to throw light by aid of these simplified inartistic and symbolic drawings on the migrations of very early races in the south and south-east of Europe, and to connect them perhaps with North African contemporary races. The subject is as difficult as it is fascinating. Those who wish to get to the original sources of information should consult the last ten years' issues of the invaluable French periodical called "L'Anthropologie," edited by Professor Marcelin Boule.

Fig. 29.—A piece of mammoth ivory carved with spirals and scrolls from the cave of Arudy (Hautes Pyrénées). Same size as the object.

FOOTNOTE:

[3] M. Reinach relates ("Repertoire de l'Art Quatermaire") that two of these statues were in 1912 deliberately stolen by the German Verworn professor of Physiology in Bonn, who repaid the hospitality of M. Lalanne by bribing his workman and secretly carrying off these valuable specimens to Germany, where (it is stated) they were sold to the museum of Berlin for a large sum.

CHAPTER IV

VESUVIUS IN ERUPTION

AT intervals of ten to twenty years the best-known volcano in the world—Vesuvius, on the Bay of Naples—has in the last two centuries burst into eruption, and the probability of the recurrence of this violent state of activity, at no distant date, render some account of my own acquaintance with that great and wonderful thing seasonable. We inhabitants of the West of Europe have little personal experience of earthquakes, and still less of volcanoes, for there is not in the British Islands even an "extinct" volcanic cone to remind us of the terrible forces held down beneath our feet by the crust of the earth. In regions as near as the Auvergne of Central France and the Eiffel, close to the junction of the Moselle with the Rhine, there are complete volcanic craters whose fiery origin is recognized even by the local peasantry. They are, however, regarded by these optimist folk as the products of ancient fires long since burnt out. The natives have as little apprehension of a renewed activity of their volcanoes as we have of the outburst of molten lava and devastating clouds of ashes and poisonous vapour from the top of Primrose Hill. Nevertheless, the hot springs and gas issuing from fissures in the Auvergne show that the subterranean fires are not yet closed down, and may at any day burst again into violent activity.

Such also was the happy indifference with which from time immemorial the Greek colonists and other earlier and later inhabitants of the rich and beautiful shores of the Neapolitan bay before the fateful year A.D. 79, had regarded the low crater-topped mountain called Vesuvius or Vesbius, as well as the great circular forest-grown or lake-holding cups near Cumæ and the Cape Misenum, at the northern end of the bay—known to-day as the Solfatara, Astroni, Monti Grillo, Barbaro, and Cigliano—and the lakes Lucrino, Averno, and Agnano. These together with the Monte Nuovo—which suddenly rose from the sea near Baiæ in 1538 and as suddenly disappeared—constitute "the Phlegræan fields." Vesuvius was loftier than any one of the Phlegræan craters, and the gentle slope by which it rose from the sea level to a height of nearly 3700 ft. had, as now, a circumference of ten miles. It did not terminate in a "cone," as in later ages, but in a depressed, circular, forest-covered area measuring a mile across, which was the ancient crater. A drawing showing the shape of the mountain at this period is the work of the late Prof. Phillips of Oxford (Fig. 30). The soil formed around and upon the ancient lava-streams of Vesuvius appears to have been always especially fertile, so that flourishing towns and villages occupied its slopes, and the ports of Herculaneum, Pompeii, and Stabiæ were the seats of a busy and long-established population. The existence of active volcanoes at no great distance from Vesuvius was, however, well known to the ancient Greeks and Romans. The great Sicilian mountain, Etna—more than 10,000 ft. in height, rising from a base of ninety miles in circumference—and the Lipari Islands, such as Stromboli and Volcano, were for many centuries in intermittent activity before the first recorded eruption of Vesuvius—that of A.D. 79—and great eruptions are recorded as having occurred in the mountain mass of the island of Ischia, close to the Bay of Naples, in the fifth, third, and first centuries B.C.

Fig. 30.—Vesuvius as it appeared before the eruption of August 24, A.D. 79. From a sketch by Prof. Phillips, F.R.S.

Nevertheless, the outburst of Vesuvius in A.D. 79 and its re-entrance into a state of activity came upon the unfortunate population around it as an absolutely unexpected thing. At least a thousand years—probably several thousand years—had passed since Vesuvius had become "extinct." All tradition of its prehistoric activity had disappeared, though the learned Greek traveller Strabo had pointed out the indications it presented of having been once a seat of consuming fire. From A.D. 63 there were during sixteen years frequent earthquakes in its neighbourhood, which, as we know by records and inscriptions, caused serious damage to the towns around it, and then suddenly, on the night of Aug. 24, A.D. 79, vast explosions burst from its summit. A huge black cloud of fine dust and cinders, lasting for three days, spread from it for twenty miles around, streams of boiling mud poured down its sides, and in a few hours covered the city of Herculaneum, whilst a dense shower of hot volcanic dust completely buried the gay little seaside resort known as Pompeii. Many thousand persons perished, choked by the vapours or overwhelmed by the hot cinders or engulfed in the boiling mud.

The great naturalist Pliny was in command of the fleet at Cape Misenum, and went by ship across the bay to render assistance to the inhabitants of the towns at the foot of Vesuvius. Pliny's nephew wrote two letters to the historian Tacitus, giving an account of these events and of the remarkable courage and coolness of his uncle, who, after sleeping the night at Stabiæ, was suffocated by the sulphurous vapours as he advanced into the open country near the volcano. The friends who were with him left him to his fate and made their escape. The younger Pliny had prudently remained, out of danger, with his mother at Misenum.

The alternating periods of activity and of rest exhibited by volcanoes seem to us capricious, and even at the present day are not sufficiently well understood to enable us to discern any order or regularity in their succession. Vesuvius is a thousand centuries old, and we have only known it for thirty. We cannot expect to get the time-table of its activities on so brief an acquaintance. Strangely enough, Vesuvius, having, after immemorial silence, spasmodically burst into eruption and spread devastation around it, resumed its slumber for many years. There is no mention of its activity for 130 years after A.D. 79. Then it growled and sent forth steam and cinder-dust to an extent sufficient to attract attention again; its efforts were thereafter recorded once or so in a century, though little, if any, harm was done by it. In A.D. 1139 there was a great throwing-up of dust and stones, with steam, which reflected the light of molten lava within the crater, and looked like flames. And then for close on 500 years there was little, if any, sign of activity. The "eruptions" between that of A.D. 79 and that of A.D. 1139 had been ejections of steam and cinders, unaccompanied by any flow or stream of lava. Then suddenly the whole business shut up for 500 years, and after that—also quite suddenly—in 1631, a really big eruption took place, exceeding in volume the catastrophe of Pliny's date. Not only were columns of dust and vapour ejected to a height of many miles, but several streams of white-hot lava overflowed the edge of the crater and reached the seacoast, destroying towns and villages on the way. Some of these lava-streams were five miles broad, and can be studied at the present day. As many as 18,000 persons were killed.

There were three more eruptions in the seventeenth century, and from that date there set in a period of far more frequent outbursts, which have continued to our own times. In the eighteenth century there were twenty-three distinct eruptions, lasting each from a few hours to two or three days, and of varying degrees of violence—a vast steam-jet forcing up cinders and stones from the crater into the air, usually accompanied by the outflow of lava, from cracks in sides of the crater, in greater or less quantity. In the nineteenth century there were twenty-five distinct eruptions, the most formidable of which were those of 1822, 1834, and 1872. All of the eruptions of Vesuvius in the last 280 years have been carefully described, and most of them recorded in coloured pictures (a favourite industry of the Neapolitans), showing the appearance of the active volcano both by day and night and its change of shape in successive years. Sir William Hamilton, the British Ambassador at the Court of Naples at the end of the eighteenth century (of whose great folio volumes I am the fortunate possessor), largely occupied himself in the study and description of Vesuvius, and published illustrations of the kind mentioned above, showing the appearance of the mountain at various epochs. Since his day there has been no lack of descriptions of every succeeding eruption, and now we have the records of photography.

The crater or basin formed by a volcano starts with the opening of a fissure in the earth's surface communicating by a pipe-like passage with very deeply-seated molten matter and steam. Whether the molten matter thus naturally "tapped" is only a local, though vast, accumulation, or is universally distributed at a given depth below the earth's crust, and at how many miles from the surface, is not known. It seems to be certain that the great pressure of the crust of the earth (from five to twenty-five miles thick) must prevent the heated matter below it from becoming either liquid or gaseous, whether the heat of that mass be due to the cracking of the earth's crust and the friction of the moving surfaces as the crust cools and shrinks, or is to be accounted for by the original high temperature of the entire mass of the terrestrial globe. It is only when the gigantic pressure is relieved by the cracking or fissuring of the closed case called "the crust of the earth" that the enclosed deep-lying matter of immensely high temperature liquefies, or even vaporizes, and rushes into the up-leading fissure. Steam and gas thus "set free" drive everything before them, carrying solid masses along with them, tearing, rending, shaking "the foundations of the hills," and issuing in terrific jets from the earth's surface, as through a safety valve, into the astonished world above. Often in a few hours they choke their own path by the destruction they produce and the falling in of the walls of their briefly-opened channels. Then there is a lull of hours, days, or even centuries, and after that again, a movement of the crust, a "giving" of the blockage of the deep, vertical pipe, and a renewed rush and jet of expanding gas and liquefying rock.

The general scheme of this process and its relations to the structure and properties of the outer crust and inner mass of the globe is still a matter of discussion, theory and verification; but whatever conclusions geologists may reach on these matters, the main fact of importance is that steam and gases issue from these fissures with enormous velocity and pressure, and that "a vent" of this kind, once established, continues, as a rule, to serve intermittently for centuries, and, indeed, for vast periods to which we can assign no definite limits. The solid matter ejected becomes piled up around the vent as a mound, its outline taking the graceful catenary curves of rest and adjustment to which are due the great beauty of volcanic cones. The apex of the cone is blown away at intervals by the violent blasts issuing from the vent, and thus we have formed the "crater," varying in the area enclosed by its margin and in the depth and appearance of the cup so produced. At a rate depending on the amount of solid matter ejected by the crater, the mound will grow in the course of time to be a mountain, and often secondary craters or temporary openings, connected at some depth with the main passage leading to the central vent, will form on the sides of the mound or mountain. Sometimes the old crater will cease to grow in consequence of the blocking of its central vent and the formation of one or more subsidiary vents, the activity of which may blast away or smother the cup-like edge of the first crater.

Fig. 31.—Five successive stages in the change of form of Vesuvius (after Phillips' "Vesuvius," Oxford, 1869). In the oldest (lowest figure) we see the mountain with its still earlier outline completed by the cone drawn in dotted line. Within the period of historic record that cone had not been seen. The mountain had, so far as men knew, always been truncated as shown here and in Fig. 30. The next figure above shows the further lowering of the mountain by the first eruption on record—that which destroyed Pompeii in A.D. 79. The commencing formation of a new ash-cone is indicated by a dotted line. In the three upper figures we trace the gradual growth of the new cone from 1631 to 1868. In 1872 the top of the new ash-cone was blown away, and the mountain reverted to the shape of 1822. Now (1920) the cone has accumulated once more and is higher than it was in 1868.

Such a history has been that of Vesuvius shown in outline in Fig. 31. In geologic ages—perhaps some thousands of centuries ago—Vesuvius was probably a perfect cone (its outline is shown at the bottom of p. 62) some 7000 ft. high, rising by a characteristically accelerated upgrowth from a circle of ten miles or more in diameter to its delicate central peak, hollowed out at the summit by a small crater a couple of hundred yards across. Its eruptions at that time were neither excessive nor violent. Then came a period of greatly increased energy—the steam-jet blew with such violence that it shattered and dispersed the cone, lowering the mountain to 3700 ft. in height, truncating it and leaving a proportionately widened crater of a mile and a half in diameter. And then the mountain reposed for long centuries. We do not know how long this period of extinction was, for we do not know when it began, but we know that this was the state of the mountain when in A.D. 79 it once more burst into life. In recent years—that is, since the seventeenth century A.D., a curious change took place in the mountain: the vent or orifice of the conducting channel by which eruptive matters were brought to the surface ceased to be in the centre of the wide broken-down crater of Pliny's time, and a vent was formed a few hundred yards to the south of the centre of the old crater, nearer to the south side of the old crater's wall. From this ashes or cinders issued, and were piled up to form a new cone, which soon added 600 ft. to the height of the mountain and covered in the southern half of the old crater's lip, whilst leaving the northern half or semicircle free. This latter uncovered part was called by the Italians "Monte Somma," and the new cone low down in the southern side of which the rest of the old crater-lip could be traced, was henceforth spoken of as "the ash-cone" and sometimes misleadingly as "the true" Vesuvius. Clearly it was not "the true Vesuvius" since it was a new growth. The original old Vesuvius was crowned by a crater formed by the cliffs of Monte Somma and their continuation round to the south side, now more or less completely concealed by the new ash-cone.

In the course of various eruptions during the last two centuries the new ash-cone thus formed was blown away more or less completely, and gradually grew up again. During the nineteenth century it was a permanent feature of the mountain, though a good deal cut down in 1822, and later grew so high as to give a total elevation from the sea-level of 4300 ft. The crater at the top of the ash-cone has varied during the past century in width and depth, according to its building up or blowing away by the central steam jet. In 1822 it is reported to have been funnel-like and 2000 ft. deep, tapering downwards to the narrow fissures which are the actual vent. At other times it has been largely filled by débris, and only 200 ft. deep. Molten lava has often issued from fissures in the sides of the ash-cone, and even lower down on the sides of the mountain, and a very small secondary crater has sometimes appeared on the side of the ash-cone 100 ft. or 200 ft. from the terminal crater which "finishes off" the cone.

Such was the condition of the mountain when I first saw it in the autumn of 1871. Six months later I witnessed the most violent eruption of the nineteenth century. Vesuvius kept up a continuous roar like that of a railway engine letting off steam when at rest in a covered station only a thousandfold bigger. Its vibrations shook with a deep musical note, for twenty-four hours, the house nine miles distant in Naples in which I was staying. My windows commanded a view of the mountain, and when the noise ceased and the huge steam-cloud cleared away, I saw a different Vesuvius, the higher part of the ash-cone was gone, and a huge gap in it had been formed by the blowing away of its northern side.

In October 1871, when I joined my friend Anton Dohrn at Naples in order to study the marine creatures of the beautiful bay, Vesuvius was in the proud possession of a splendid cone, completing its graceful outline. A little steam-cloud hung about one side of the cone during the day, and as night came on Vesuvius used, as we said, to "light his cigar." In fact, a very small quantity of molten lava was at that time flowing from the side of the ash-cone, about 100 ft. from its summit, and this gave a most picturesque effect as we watched it from our balcony high up on Pausilippo, when the sun set. It was a friendly sort of beacon, far away on the commanding mountain's top, which was answered by the lighting up of a thousand lamps along the coast, and by innumerable flaming faggots in the fishermen's boats moving across the bay, drawing to their light strange fishes, to be impaled by the long tridents of the skilful spearmen. That little beacon light on Vesuvius increased in volume in the course of three weeks, and was supplemented by other flaming streams and by showers of red-hot stones from the crater. This small "eruption" was the precursor by six months of the great eruption of the end of April 1872, and I spent a night on Vesuvius during its progress, and looked into the crater from which the glowing masses of rock were being belched forth.

Not long before I went, in 1871, to Naples I had spent some weeks in visiting the extinct volcanoes of the Auvergne and of the Eiffel, and I was eager to examine the still living Vesuvius. In the first week of October I made an excursion to the crater of Vesuvius in company with the son of a Russian admiral, whose name, "Popoff," was under the circumstances unpleasantly suggestive. We examined some black slaglike masses of old lava-streams, and struggled up the loose sandy ash-cone (there was no "funicular" in those days), and prodded with our sticks the few yards of molten lava which emerged from the side of the cone about 100 ft. from the summit. On Nov. 1 my friend Anton Dohrn (who was then negotiating with the Naples Municipality for a site in the Villa Nazionale on which to erect the great Zoological Station and Aquarium, now so well known) was with me and some Neapolitan acquaintances looking at Vesuvius across the bay from Pausilippo, where we had established ourselves, when we noticed that a long line of steam was rising from the lower part of the ash-cone and that puffs of steam were issuing at intervals from the crater. "Dio mio! Dio di Dio!" cried the Neapolitans in terror, and expressed their intention of leaving Naples without an hour's delay. As night fell a new glowing line of fire appeared far down near the base of the ash-cone, whilst what looked in the distance like sparks from a furnace, but were really red-hot stones—each as big as a Gladstone bag—were thrown every two or three minutes from the crater.

We hired a carriage, drove to Resina (built above buried Herculaneum), and walked up towards the Observatory in order to spend the night on the burning mountain. We found that two white-hot streams, each about twenty yards broad at the free end, were issuing from the base of the cone. The glowing stones thrown up by the crater were now separately visible; a loud roar accompanied each spasmodic ejection. The night was very clear, and a white firmly-cut cloud, due to the steam ejected by the crater, hung above it. At intervals we heard a milder detonation—that of thunder which accompanied the lightning which played in the cloud, giving it a greenish illumination by contrast with the red flame colour reflected on to it by red-hot material within the crater. The flames attributed to volcanoes are generally of this nature, but actual flames do sometimes occur in volcanic eruptions by the ignition of combustible gases. The puffs of steam from the crater were separated by intervals of about three minutes. When an eruption becomes violent they succeed one another at the rate of many in a second, and the force of the steam jet is gigantic, driving a column of transparent super-heated steam with such vigour that as it cools into the condition of "cloud" an appearance like that of a gigantic pine-tree seven miles high (in the case of Vesuvius) is produced.

We made our way to the advancing end of one of the lava-streams (like the "snout" of a glacier), which was 20 ft. high, and moved forwards but slowly, in successive jerks. Two hundred yards farther up, where it issued from the sandy ashes, the lava was white-hot and running like water, but it was not in very great quantity and rapidly cooled on the surface and became "sticky." A cooled skin of slag was formed in this way, which arrested the advancing stream of lava. At intervals of a few minutes this cooled crust was broken into innumerable clinkers by the pressure of the stream, and there was a noise like the smashing of a gigantic store of crockery ware as the pieces or "clinkers" fell over one another down the nearly vertical "snout" of the lava-stream, whilst the red-hot molten material burst forward for a few feet, but immediately became again "crusted over" and stopped in its progress. We watched the coming together and fusion of the two streams and the overwhelming and burning up of several trees by the steadily, though slowly, advancing river of fire. Then we climbed up the ash-cone, getting nearer and nearer to the rim of the crater, from which showers of glowing stones were being shot. The deep roar of the mountain at each effort was echoed from the cliffs of the ancient mother-crater, Monte Somma, and the ground shook under our feet as does a ship at sea when struck by a wave. The night was very still in the intervals. The moon was shining, and a weird melancholy "ritornelle" sung by peasants far off in some village below us came to our ears with strange distinctness. It might have been the chorus of the imprisoned giants of Vulcan's forge as they blew the sparks with their bellows and shook the mountains with the heavy blows of their hammers.

As we ascended the upper part of the cone the red-hot stones were falling to our left, and we determined to risk a rapid climb to the edge of the crater on the right or southern side, and to look into it. We did so, and as we peered into the great steaming pit a terrific roar, accompanied by a shuddering of the whole mountain, burst from it. Hundreds of red-hot stones rose in the air to a height of 400 ft., and fell, happily in accordance with our expectation, to our left. We ran quickly down the sandy side of the cone to a safe position, about 300 ft. below the crater's lip, and having lit our pipes from one of the red-hot "bombs," rested for a while at a safe distance and waited for the sunrise. A vast horizontal layer of cloud had now formed below us, and Vesuvius and the hills around Naples appeared as islands emerging from a sea. The brilliant sunlight was reassuring after this night of strange experiences. The fields and lanes were deserted in the early morning as we descended to the sea-level. On our way we met a procession of weird figures clad in long white robes, enveloping the head closely but leaving apertures for the eyes. They were a party of the lay-brothers of the Misericordia carrying a dead man to his grave. Then we found our carriage, and drove quickly back to Naples and sleep!

In the following March I acted as guide to my friend Professor Huxley in expeditions up Vesuvius, now quiescent, and to the Solfatara. Then suddenly, in April, the great eruption of 1872 burst upon us. On the first day of the outbreak some imprudent visitors were killed by steam and gas ejected by the lava-stream. By the next day the violence of the eruption was too great for any one to venture near it. The crater sent forth no intermittent "puffs" as in the preceding November, but a continuously throbbing jet which produced a cloud five miles high, like an enormous cauliflower in shape, suspended above the mountain and making it look by comparison like a mole-hill. Showers of fine ashes, as in the days of Pompeii, fell thickly around, accumulating to the depth of an inch in a few hours even at my house in Pausilippo, nine miles distant across the bay. I was recovering at the time from an attack of typhoid fever, and lay in bed, listening to the deep humming sound and wondering at the darkness until my doctor came and told me of the eruption. I was able to get up and see from the window the great cauliflower-like cloud and the vacant place where the ash-cone was, but whence it had how been scattered into the sky. (It has been gradually re-formed by later eruptions, of which the last of any size was in 1906.) I could also see steam rising like smoke from a long line reaching six miles down the mountain into the flat country below. It was the great lava-stream which had destroyed two prosperous villages in its course.

After ten days I was able to get about, and drove over to one of these villages and along its main street, which was closely blocked at the end by what looked like a railway embankment some 40 ft. high. This was the side of the great lava-stream now cooled and hardened on the surface. It had sharply cut the houses, on each side of the street, in half without setting them on fire, so that the various rooms were exposed in section—pictures hanging on the walls, and even chairs and other furniture remaining in place on the unbroken portion of the floor. The villagers had provided ladders by which I ascended the steep side of the embankment-like mass at the end of the street, and there a wonderful sight revealed itself. One looked out on a great river seven miles long, narrow where it started from the broken-down crater, but widening to three miles where I stood, and wider still farther on as it descended. This river, with all its waves and ripples, was turned to stone, and greatly resembled a Swiss glacier in appearance. A foot below the surface it was still red-hot, and a stick pushed into a crevice caught fire. It was not safe to venture far on to the pie-crust surface. A couple of miles away the campanile of the church of a village called Massa di Somma stood out, leaning like that of Pisa, from the petrified mass, whilst the rest of the village was overwhelmed and covered in by the great stream.

The curious resemblance of the lava-stream to a glacier arose from the fact that it was almost completely covered by a white snow-like powder. This snow-like powder, which often appears on freshly-run lava, is salt—common sea salt and other mineral salts dissolved in the water ejected as steam mixed with the lava. The steam condenses, as the lava cools, into water and evaporates slowly, leaving the salt as crystals. Often these are not white, but contain iron salt, mixed with the white sodium, potassium, and ammonium chlorides, which gives them a yellow or orange colour. Salts coloured in this way have the appearance of sulphur, and are often mistaken for it. The whole of the interior of the crater of Vesuvius when I revisited it in 1875 was thus coloured yellow, and I have a water-colour sketch of the scene made by a friend who came with me for the purpose. As a matter of fact, though small quantities of the choking gas called "sulphurous acid" are among the vapours given off by Vesuvius, there is no deposit of sulphur there. Some large volcanoes (in Mexico and Japan) have made deposits of sulphur, which are dug for commercial purposes; but the sulphur of Sicily is not, and has not been, thrown out or volatilized by Etna. It occurs in rough masses and in splendid crystals in a tertiary calcareous marine deposit, and its deposition was probably due to a chemical decomposition of constituents of the sea water brought about by minute plants, known as "sulphur bacteria." Whether the neighbouring great volcano had any share in the process seems to be doubtful.

It is generally supposed that sea-water makes its way in large quantity through fissures connected with volcanic channels, and is one of the agents of the explosions caused by the subterranean molten matter. Gaseous water, hydrochloric acid, carbonic acid, hydrofluoric acid, and even pure hydrogen and oxygen and argon are among the gases ejected by volcanoes.

The molten matter forced up from the bowels of the earth and poured out by volcanoes is made up of various chemical substances, differing in different localities, and even in different eruptions of the same volcano. It consists largely of silicates of iron, lime, magnesium, aluminium, and the alkali metals, with possible admixture of nearly every other element. Some volcanoes eject "pitch" or "bitumen." When the molten matter cools, interesting crystals of various "species" (i.e., of various chemical composition) usually form in the deeper part of the mass. The lavas of Vesuvius frequently contain beautiful opaque-white twelve-sided crystals of a siliceous mineral called "leucite." I have collected in the lava of Niedermendig, on the Rhine, specimens embedding bright blue transparent crystals (a mineral called Haüynite) scattered in the grey porous rock. The lava-streams, and even the "roots," of extinct volcanoes which are of great geologic age, sometimes become exposed by the change of the earth's surface, and extensive sheets of volcanic rock of various kinds are thus laid bare. Basalt is one of these rocks, and it not unfrequently presents itself as a mass of perpendicular six-sided columns, each column 10 ft. or more high, and often a foot or more in diameter. The "Giant's Causeway," in the North of Ireland, and the "Pavée des Géants," in the Ardêche of Southern France, are examples both of which I have visited. It is not easy to explain how the molten basalt has come to take this columnar structure on cooling. It has nothing to do with "crystallization," but is similar to the columnar formation shown by commercial "starch" and occasionally by "tabular flint". A theoretical explanation of its formation has been given by Prof. J. Thompson, brother of the late Lord Kelvin.

The varieties of volcanoes and their products make up a long story—too long to be told here. There are from 300 to 400 active craters in Existence to-day—mostly not isolated, but grouped along certain great lines, as, for instance, along the Andean chain, or in more irregular tracks. If we add to the list craters no longer active, but still recognizable, we must multiply it by ten. Vesuvius is the only active volcano on the mainland of Europe—Hecla, Etna, Stromboli, Volcano, and the volcanoes of the Santorin group are on islands. The biggest volcanoes are in South America, Mexico, Java, and Japan. Volcanoes and the related "earthquakes" have been most carefully studied with a view to the safety of the population in Japan. The graceful and well-beloved volcano, Fujiyama, is more than 12,000 ft. high, but, unlike others in those islands, it has been quiescent now for just 200 years. The most violent volcanic eruptions of recent times, with the largest "output" of solid matter, are those of the Soufrière of St. Vincent in 1812, of the Mont Pelée of Martinique in 1902, and of Krakatoa in 1883. A single moderate eruption of the great volcano Mauna Loa, in Hawaii, nearly 14,000 feet high, throws out a greater quantity of solid matter than Vesuvius has ejected in all the years which have elapsed since the destruction of Pompeii. Many hundred millions of tons of solid matter were ejected by Mont Pelée in 1902, when also a peculiar heavy cloud descended from the mountain, hot and acrid, charged with incandescent sand, and rolling along like a liquid rather than a vapour. It burnt up the town of St. Pierre and its inhabitants and the shipping in the harbour. In the eruption of the volcano of St. Vincent in 1812 three million tons of ashes were projected on to the Bahamas Islands, 100 miles distant, besides a larger quantity which fell elsewhere. The great explosion at Krakatoa, lasting two days, blew an island of 1400 ft. high, into the air. A good deal of it was projected as excessively fine needlelike particles of pumice with such force as to carry it up thirty miles into the upper regions of the atmosphere, where it was carried by air currents all over the world, causing the "red sunsets" of the following year. The sky over Batavia, 100 miles distant, was darkened at midday so completely that lamps had to be used—as I heard from my brother who was there at the time. The explosions were heard in Mauritius, 3000 miles away. A sea wave 50 ft. high was set going by the submarine disturbance, and reaching Java and neighbouring islands inundated the land and destroyed 36,000 persons. This wave travelled in reduced size over a vast tract of the ocean, and was observed and recorded at Cape Horn, 7800 miles distant from its seat of origin.

CHAPTER V

BLUE WATER

MOST people know and admire the splendid expanse of blue colour offered by the clear sea water on many parts of our coasts, and by that of lakes at home and abroad. I find that there is still a sort of a fixed determination not to believe that this colour is due (as it is) to the actual blue colour of pure water. Pure, transparent water is blue. Those who think they know better will point to a glass of pure water, hold it up to the light, and affirm that it is colourless. But this apparent colourlessness is due to the small breadth of water in the glass through which the light passes. It is definitely ascertained that if water as pure and as free from either dissolved or suspended matter as it is possible to make it (by distillation and the use of vessels not acted upon by water) be made to fill an opaque tube 15 ft. long, closed at each end by a transparent plate, and then a beam of light be made to traverse the length of the tube, so that the eye receives the light after it has passed through this length of 15 ft. of water, the colour of the light is a strong blue. Water is blue in virtue of its own molecular character, just as sulphate of copper is. Liquid oxygen, prepared by the use of intense cold, is also transparent blue, and the peculiar condensed form of oxygen known as "ozone" is, when liquefied, of a darker or stronger blue than oxygen.

At one time (some thirty years ago) there was still some doubt as to whether water was self-coloured blue, or whether its blue colour was due to the action on light of excessively minute solid white particles of chalk suspended in the water. Such fine suspended particles in some cases act on the light which falls on to them so as to reflect the blue rays. This occurs in certain natural objects which have a blue colour. But these can be distinguished from transparent self-coloured blue substances by the fact that whilst the light reflected from their surface is blue, the light which is made to traverse them (when they are held up to the light so that they come between one's eye and the sun's rays) is brown. This is the case with very hot smoke, and can be well seen when a cigar is smoked in the sunlight. The smoke which comes off from the lighted end of the cigar is very hot, and its particles are more minute than those of cooler smoke. The hot smoke shows a bright blue colour when the sunlight falls on it and is reflected, but when you look through the smoke-cloud at a surface reflecting the sunlight, the cloud has a reddish-brown tint. As the smoke cools its particles adhere to one another and form larger particles, and the light reflected from the cloud is no longer blue but grey, and even white. Thus the smoke which the smoker keeps for half a minute in his mouth is cooled and condensed, and reflects white light—is, in fact, a white cloud—when he puffs it out, and contrasts strongly with the blue cloud coming off from the burning tobacco at the lighted end of the cigar. The blue colour of the sky is held by many physicists (though other views have been of late advanced) to be due to the same action on the part of the very finest particles of watery vapour, which are diffused through vast regions of our atmosphere above the condensed white-looking clouds consisting of larger floating particles of water.

Vapours are given off by many liquids, and even by some solids, varying in their production according to the heat applied in different cases. They are gases, and quite transparent and invisible at the proper temperature, like the atmospheric air. Thus water is always giving off "water-vapour," which is quite invisible. When water is heated to the boiling point it is rapidly converted into transparent invisible vapour. Steam, as this vapour is called, is invisible, and we all habitually make a misleading use of the word "steam" when we apply it both to this and to the slightly cooled and condensed cloud which we can see issuing from the spout of a kettle or from a railway engine. It seems that the fault lies with the scientific writers, who have applied the word "steam" to the invisible water vapour or gas before it has condensed to form a cloud. The old English word "steam" certainly means a visible cloudy emanation, and not a transparent invisible gas. A cloud is not a vapour, but is produced by the coming together or condensation of the minute invisible particles of a vapour to form larger particles, which float and hang together, and reflect the light, and thus are visible.

By the examination of other vapours or gases than that which is gaseous water, namely, the vapours of bodies like chloroform and ether, it has been shown that "cloud" forms in a vapour not merely in consequence of the cooling of the vapour, but in consequence of the presence in the air (or in the tube in which the vapour is enclosed for observation) of very fine floating dust particles. They act as centres of attraction and condensation for the vapour particles. When there are no dust particles present clouds do not form readily in cooling vapours, or only at lower temperatures, and in larger mass. Tyndall made some beautiful experiments on this subject, obtaining clouds of great tenuity in vapours enclosed in tubes, which reflected the most vivid blue tints when illuminated by the electric arc-lamp. Later Aitken, of Edinburgh, showed that the "fog" which forms in smoke-ridden towns is due to the condensation of previously invisible watery vapour as "cloud" around the solid floating particles of carbon of the smoke. Aitken further used this property of solid floating particles, namely, that they cause the formation of fog and cloud in vapours—to test the question as to whether the excessively minute odoriferous particles which affect our noses as "smell" are distinct solid floating particles as often supposed, or are of the nature of gas and vapour. He admitted strong perfumes such as musk into tubes containing watery vapour, at such a temperature that the vapour was in a "critical" state—just ready to condense and precipitate as "cloud." If he had admitted fine solid particles such as a minute whiff of smoke, or some "dusty" air—the cloud would have formed. But the admission of the perfume had no such effect Therefore, he concluded that the odoriferous emanations used by him are not distinct particles like those of smoke or dust, but are gaseous.

The beautiful blue tint of the semi-transparent "white" of a boiled plover's egg is due to a fine-particled cloud dispersed in the clear albumen. London milk used to be "sky-blue" for a similar reason, before the recent legislation against the adulteration of food. The blue eyes of our fair-haired race and of young foxes are not due to any "pigment"—that is to say, a separable self-coloured substance—but to a fine cloud floating in a transparent medium which reflects blue rays of light as blue smoke does. The iris of the eye can and often does develop a pigment, but it is a brown one. When present in small quantity it produces a green-coloured iris, the pale yellow-brown being added to the blue cloud-caused colouring. When present in larger quantity the same pigment gives us brown and so-called "black" eyes. The blue colours in birds' feathers and insects' wings are produced without blue pigment by special effects of reflection, and where green is the colour it is often due to the addition of a small quantity of yellow pigment to what would otherwise look blue: though some caterpillars and grasshoppers have a real green pigment in their skin. Flowers, on the other hand, have true soluble blue "pigments," and green ones too, notably that called leaf-green or chlorophyll. The little green tree frog has no blue or green pigment in its skin; only a yellow pigment. Sometimes rare specimens are found in which the yellow pigment is absent altogether, and then the little frog is turquoise-blue in colour. But there is no blue pigment in the skin; only a finely-clouded translucent film overlying a dead-black deep layer of the skin, and the result is that the frog is of a wonderful pure blue. Sometimes the commoner large edible frog is found with a similar absence of yellow pigment (I found some in a garden near Geneva six years ago), and then all the parts of its skin which usually are green show as brilliant blue.

It is at first difficult to believe that such fine, smoothly-spread turquoise blue as that of the blue frog is due merely to a "reflection effect," and that there is no blue pigment present which would show as blue if light were transmitted through it, or could be separated and dissolved in some medium. Yet this is undoubtedly the case. The nearest experimental production of such a blue surface without blue pigment is obtained by first varnishing a black board, and when the varnish is nearly dry passing a sponge wetted with water over it. Some of the varnish is precipitated from its solution in the spirit (or it may be turpentine) as a fine cloud, and until the water has evaporated it looks like blue paint, as the poet Goethe found when cleaning a picture. It would be interesting to know more precisely the precautions to be taken in order to get the blue colour in this way in fullest degree.

It appears that when light is reflected from a cloud of fine colourless particles so as to give a predominant blue colour, the light so reflected is affected in that special way which physicists describe as being "polarized." It is possible by the use of certain apparatus (the polariscope) to distinguish polarized from non-polarized light, so that it should be possible to decide (or at any rate to gain evidence) whether blue water—a sheet of blue water—owes its colour to fine particles suspended in it or to the self-colour of the water. An admirable case for making this simple experiment is presented by the great tanks—some 20 ft. cube—which are used by the water companies which draw their water supply from the chalk, for the purpose of precipitating the dissolved chalk—"Clarking" the water, as it is called, after the inventor of the process—and so getting rid of its excessive "hardness." Such tanks are to be seen by the side of the railway near Caterham. The water in these tanks is of such a brilliant turquoise blue that many people suppose that copper has been added to the water to free it from microbes! Such, at any rate, was the conviction expressed by a friend in conversation with me only a few weeks ago. The water in these tanks, when seen from the railway, looks like a magnificent blue dye, and a very important point for those (not a few) who believe that the blue colour of seas and lakes is due to the reflection of the blue colour of the sky overhead is that the water in the tanks looks just as blue when the sky is overcast with cloud as when there is blue sky. The blue colour of water has, as a rule, nothing to do with the reflection of the sky, though it is the fact that a shallow film of water may at a certain angle reflect the sky to our eyes, just as a mirror may. The effect is quite unlike that due to light passing through deep water when reflected from below it. If we examine the tanks in question we find that they have been filled with water pumped from the chalk, and that then lime has been added to the water in order to combine with the carbonic acid dissolved in it and form chalk or carbonate of lime—which is insoluble in pure water and falls as an excessively fine white powder to the bottom of the tank. But the important fact is that water having carbonic acid dissolved in it can dissolve carbonate of lime or chalk to a certain amount: and this water pumped from the chalk, having carbonic acid naturally dissolved in it, has consequently also dissolved a quantity of chalk. It is this which gives the chalk-spring water the objectionable quality of "hardness." When lime is added to the chalk-spring water as pumped into the tanks, the carbonic acid in it is taken up by the lime, and the chalk previously dissolved by the carbonic-acid-holding water is, so to speak, "undissolved," and thrown down as a very fine white powder, together with the chalk newly formed by the union of the lime and the carbonic acid. These large tanks are used to allow the fine powder of chalk to settle down and leave the water clear. The brilliantly white chalk sediment accumulates not only on the floor of the tank, but on its sides. Any light which falls on the tank is refracted and reflected from side to floor and from floor to side, and eventually emerges from the tank, a great deal of it having traversed the 20 ft. breadth and depth many times. Most of its red, yellow, and green rays are quenched by the many feet of blue water through which it has passed, and it issues as predominantly blue. This is largely due to the fine reflecting surface furnished by the "white-washed" or chalk-coated floor and sides and the great purity of the white reflecting material—no yellow or brown matter being present to give a greenish tinge to the result I remember being taken to see "Clark's process" in use, and the splendid blue colour of the water in the "softening" tanks at Plumstead, when the process was first used by the North Kent Water Company, sixty-four years ago.

It is, I think, still a possible question as to whether the fine floating particles of precipitating chalk act in any way as a "cloud"—in short, as the blue clouds of smoke, egg-white, milk, and varnish. There is no evidence that they do, but no one, so far as I know, has ever taken the trouble to settle the question. It could be done by examining the blue light from the tanks with a polariscope, and also by sinking a black tarpaulin into the tank to cover the white floor and hanging others at the sides. Then if the blue colour were due to light reflected from the white floor and sides traversing repeatedly the clear self-coloured blue water, the blue colour should no longer be visible, for the reflecting surfaces would be covered by the black tarpaulin and little light sent up through the water. But if it were due to a cloud of greatest delicacy in the water—like fine smoke reflecting the blue light rather than the other rays—then the colour should be as intense or more intense when the black background is introduced. I am surprised that some inquirer, younger and more active than I am, does not put the matter to the test of experiment.

On the whole, practically all the facts which we know about "blue water" are consistent with the blue self-colour of water, and not with that of a "blue cloud" in the water. Now that we have porcelain baths of the purest white and of large size, one may often see the strong blue colour of water of great purity in the bath, especially where waves or ripples send to our eyes those rays of light which have taken a more or less horizontal course from side to side of the bath, and have thus been through a large thickness of the pale-coloured fluid. Great masses of clear ice, such as one may study in glaciers, are blue; the "crevasses" which transmit light which has passed through a considerable thickness of ice (as, for instance, in an ice cave), are deep blue; there is no question of a reflection from suspended particles. The green colour which some glaciers show at a little distance is due to the yellow rust—iron oxide—blown on to the surface of the ice and dissolved. Many glaciers or parts of glaciers are quite free from it, and of a splendid indigo blue in their deeper fissures. So, too, as to the sea and lakes. The Blue Grotto or Cavern of the island of Capri, near Naples, is a case in point. All the light which enters it comes through the sea-water and is blue. I was taken to it in a boat rowed by two men. As the boat enters the low mouth of the cavern you have to bend down to avoid knocking your head against the rock. Then you find yourself floating in a vast and lofty chamber the white rocky floor of which is some twenty feet below the surface of the clear water. No light enters the cavern by the low part of the entrance above water. Below the surface it widens and the strong Southern sun shines through the clear water and its light is reflected up into the cave from the bottom. It is blue, and everything in the cave above as well as below the water is suffused with a blue glow—a truly wonderful and fascinating spectacle. In order to get the best effect you must choose an hour when the sun is in a favourable position. Where there is a white bottom at a depth of fifty or a hundred feet, the sea has a fine ultra-marine colour, so long as it is clear. It is often made green by yellow-coloured impurities, either fine iron-stained sediment or by minute living things in the water. The colour of the water of either sea or lakes, when it is clear and overlying great depths (200 fathoms and more), tends to be dark indigo owing to the deficiency of reflected light. But there are enough white particles as a rule to send some of the light, which penetrates the water, upwards again. Even the great ocean has a dark purplish-blue colour, but never the bright blue of clear water in shallow seas with light-coloured or white bottom.

One of the most beautiful exhibitions of the colour of clear water in various thicknesses which I know, is at the entrance of the Rhone into the Lake of Geneva. The thick pale-coloured brownish-white sediment of the river shoots out for a quarter of a mile or more into the dark blue waters of the deep lake, and on a bright sunny day as it subsides reflects the light upwards from different depths through the clear water. Where it has sunk but little the colour is green, owing to the influence of the yellow mud. Farther on it is ultra-marine blue, and then, where it has sunk deeper, we get full indigo tints. The movement of the water and its churning up by the steamers' paddles add to the variety of effects, since the foam of air-bubbles submerged throws up the light through the water. It is not possible to doubt as one watches the admixture of the river and the lake, and the eddies and hanging walls of sediment, that one is floating over a vast depth of magnificent blue self-coloured fluid which is traversed by the sunlight in ways and degrees varying according to its depth and the volume of the pale mud of the in-rushing Rhone and the abundance of fine air-bubbles "churned" into the water by the paddle-wheels of the steamer.

CHAPTER VI

THE BIGGEST BEAST

THERE is a prevalent notion, encouraged by the fanciful exaggerations of newspaper gossips, that the animals of past ages, whose bones are from time to time dug out of rocks and sand quarries, were many of them much bigger than any at present existing, and that we are living in an age of degeneracy. It is true that the mammoth and the mastodon were enormous creatures, but they were not bigger than their living representatives, the great elephants of Africa and India. The African elephant often stands 11 ft. high at the shoulder, and occasionally attains 12 ft.

Some eighty years ago Dr. Gideon Mantell became celebrated by his discovery of the bones of huge reptiles—far bigger than any existing crocodile or lizard—nearly as big as elephants, in the Wealden rocks of Tilgate Forest in Sussex. He and Sir Richard Owen distinguished several kinds—the Iguanodon, the Megalosaurus, the Hylæosaurus, and others. Models of these creatures as they appeared when clothed in flesh and hide were carefully made, and placed picturesquely among the ponds and islands of the gardens of the Crystal Palace at Sydenham when it was first opened to an enchanted public in the fifties. As a small boy I, at that time, fell under their spell.

The passing years have brought to us more complete knowledge of these strange beasts—now classed as the "Dinosauria"—and new kinds and complete skeletons of those already known have been discovered in the United States and in Belgium. The leg bones and vertebræ of one of the biggest were found near Oxford, and are in the Oxford Museum; it received the name Cetiosaurus. Only a few years ago a very complete skeleton of a creature closely allied to Cetiosaurus was with great labour and skill dug out of the Jurassic rocks of Wyoming, U.S.A., by Dr. Holland, at the charges of Mr. Andrew Carnegie. It was known as Diplodocus (referring to certain bones in its tail), and a wonderful cast of the completely reconstructed skeleton was presented to the Natural History Museum in London, when I was Director, by Mr. Carnegie. The skeleton is 84 ft. long; but we must not be mis-led as to the animal's actual bulk by this measurement, for the tail is 46 ft. long and whip-like, whilst the neck is 23 ft. long and carries a small head not bigger than that of a cart-horse. The jaws were provided with small peg-like teeth, showing that the beast fed on soft vegetable matter. The body, apart from neck and tail, was really only a little bigger than that of a large elephant, and the limb-bones longer in the proportion of about six to five. Another reptile very similar to these and also found in the mesozoic rocks of the U.S. America is Brontosaurus.

The fact is that, if we wish to make an intelligent comparison of the sizes of different animals, we have carefully to ascertain not merely the length measurements, but the proportions of the various parts, and the actual bulk and probable weight of the beasts under consideration. Also (and this is a very important and decisive matter) we must know whether the beasts were terrestrial in habit, walking with their bodies raised high on their legs, or whether they were aquatic and swam in the lakes or seas, their bodies buoyed up and supported by the water. By far the biggest animals of which we have any knowledge are the various kinds of whales still flourishing in the sea. A mechanical limit is set to the size of land-walking animals, and that limit has been reached by the elephant "Flesh and blood," and we may add "bone," cannot carry on dry land a greater bulk than his. He is always in danger of sinking by his own weight into soft earth and bog. His legs have to be much thicker in proportion than those of smaller animals—made of the same material—or they would bend and snap. His feet have to be padded with huge discs of fat and fibre to ease the local pressure, and his legs are kept straight not bent at the joints, when he stands (a fact to which Shakespeare makes Ulysses refer), so that the vast weight of his body shall be supported by the stiff column formed by the upper and lower half of the limb-bones kept upright in one straight line. A well-grown elephant weighs five tons. Compare his weight and shape with that of a big whale-bone whale! No extinct animal known approaches the existing whale in bulk and weight. He is 80 to 90 ft. long, and has no neck nor any length of tail. His outline is egg-like, narrower at the hinder end. He weighs 200 tons—forty times as much as a big elephant—and is perfectly supported without any strain on his structure by the water in which he floats. There is no such limit to his possible size as there is in the case of land-walking animals. But it seems probable that he too is limited in size by mechanical conditions of another kind. Probably he cannot exceed some 90 ft. in length and 200 tons of bulk on account of the relatively great increase of proportionate size and power in the heart required in order to propel the blood through such a vast mass of living tissue and keep him "going" as a warm-blooded mammal. The original pattern—the small dog-like ancestor of the whale—cannot be indefinitely expanded as an efficient working machine, though its limit of growth is not determined by the same mechanical causes as those which limit the bulk of the terrestrial quadruped.

These considerations make it clear that we should compare as to "bigness" terrestrial animals with other terrestrial animals, and aquatic animals with aquatic ones. It seems probable that Diplodocus was an aquatic reptile, and never raised himself on to his four legs on dry land as the Carnegie skeleton at the Natural History Museum is doing. His legs and feet are quite unfitted to support his weight on a land surface; on land he would have rested on his belly, as a crocodile does, with much bent legs on each side. But submerged in 20 ft. depth of water, he could have trotted along, half-floating, with his feet touching the bottom and his head raised on its long neck to the surface, slowly sucking the floating vegetation into his moderate-sized mouth. (See drawing on p. 91.)

Diplodocus and Cetiosaurus have huge thigh-bones and upper-arm bones—respectively 5 ft. 9 in. and 3 ft. 2 in. in length—until lately the biggest known limb-bones, although the lower jaw-bone of a Right Whale grows to be 18 ft. in length. But a thigh-bone (femur) of a reptile similar to Diplodocus has been found in Wyoming, 6 ft. 2 in. in length. This reptile was named Atlantosaurus, and a cast of the huge bone—the biggest known when it was placed there—stands in our museum gallery. However, its glory has departed, for we now know "than this biggest bone, a bigger still." The bones of several individuals of a huge reptile similar to Diplodocus, but actually twice as big in linear dimensions, were found by Dr. Fraas at Tendagoroo, fifty miles from the coast in German East Africa, and brought safely to Berlin in 1912, though they have not yet been mounted as a complete specimen. They were lying in a sandy deposit of the same geologic age as our Sussex Wealden. A special expedition of 500 negroes was sent—not by the Government, but by the Berlin "Society of the Friends of Natural History" (we need such a society in England), at a cost of £10,000, to fetch the bones. They were of many individuals, and had to be skilfully dug out and packed. Dr. Fraas calls this biggest of all quadrupeds "Gigantosaurus." A cast of the humerus, or upper-arm bone, is now exhibited in the Natural History Museum. It is over 7 ft. in length. The femur, or thigh-bone, was still bigger—it was over 10 ft. in length. Alas for the glory of Atlantosaurus! This enormous creature was, of course, like Diplodocus, aquatic. Its bulk was much less than that of a big whale, but extinct aquatic reptiles may yet be found of greater size. Ichthyosaurus, the extinct whale-like reptile, does not exceed 30 ft. in length. Our engraving (Fig. 32) shows the relative size of the humerus of man, the elephant, [4] and the Gigantosaurus. How puny is that human arm-bone! And yet...!

When stretched on the shore, resting on the belly, the body of the great lizard of Tendagoroo bulked like a breakwater 12 ft. high, and his tail like a huge serpent extended 80 ft. beyond it; whilst his head and neck reached 40 ft. along the mud in front.

Fig. 32.—The upper-arm bone or humerus of the great reptile (Gigantosaurus) of Tendagoroo—compared with that of man and of an Indian elephant.

An important limitation to great size in an animal is, it must be remembered, often imposed by the nature of the animal's food. Ten individuals each weighing a hundredweight will more easily pick up and swallow the amount of food required to nourish ten hundredweight of the species than will one individual responsible for the whole bulk, provided that the food is scattered and not ready to the mouth in unlimited quantity. A creature which has unlimited forest or grass or seaweed as its food will be at no disadvantage owing to its size. But a carnivor or a fish-eater or one depending on special fruits and roots not offered to him by nature in mass has to search for, and sometimes to hunt, or at any rate to compete with others, for the scattered and elusive "bits" of food. So it is that we find that the fruit-eating apes are not very big, and that terrestrial carnivors are small, though powerful and swift, as compared with cattle, deer, and vegetarian beasts. Ten carnivors weighing each ten stone will with their ten mouths "pick up" more prey than one carnivor weighing a hundred stone and having only one mouth. Even the carnivorous Dinosaurs such as Megalosaurus and Tyrannosaurus were much smaller than the vegetarian Iguanodon, Diplodocus, Brontosaurus and Triceratops on which (or on the like of which) they preyed—just as a tiger is smaller than a buffalo, and a wolf smaller than a horse. It is owing to causes of this nature that the life of some animals, and consequently their growth, is limited in duration. Occasionally the common lobster lives to a great age, and grows to be more than 2 ft. long. But he is doomed by his size; the smaller lobsters "go quickly around" and get all the food (carrion of the sea), and the big fellow has to starve. The whale-bone whales, it is true, take animal food; but it occurs in the form of minute sea-slugs and shrimps, which fill the surface waters in countless millions over hundreds of miles of ocean. Hence the whales of this kind have only to swim along with their mouths open through an unlimited supply of luscious food. The size of terrestrial animals is also, it appears, definitely related to the natural water-supply. There are very few small quadrupeds in the interior of Africa. On account of frequent "drought," the mammals have often to run a hundred miles or more in search of water. Only animals as big as the larger antelopes and the zebra can cover the ground. The smaller kinds die (and have, in fact, died out in past ages) in these regions of sudden drought.