Chapter III: Part 3

I always look upon the Christmas Cattle Show of the Smithfield Club as a scientific delight. Breeding is a most serious branch of scientific knowledge, held by many people (of whom I am one) to be of more importance to statesmen, politicians, and philanthropists than any other kind of knowledge, and yet almost absolutely neglected and completely ignored except by our farmers and horticulturists. When examining in turn the splendid animals at Islington I have felt indignant that it should be not improbable that, owing to ignorance and neglect in official quarters, the long matured traditions and built-up skill of our cattle-breeders will be destroyed, crushed out of existence by huge, devastating capitalist “combines.” Soon we shall not get the beef we wish for, but we shall have to take whatever inferior stuff the giant monopolist chooses to force on us--or go without! Our wonderful stock, so patiently and happily bred, the envy of the world, will disappear, and our breeders forget their art. We shall none of us in Britain know more about prime beef, roasts, grills, and marrow-bones than do the people of Europe or the eaters of terrapin and soft-shelled crabs.

It is wonderful that man, by deliberate choice in selecting the sires and dams, has been able to produce such widely-different races as the short-horn, the Highland and the Sussex breed, and not only to produce them, but to keep them there generation after generation. In Nature, no such deviations are allowed--her motto is “One species, one shape,” which is only relaxed so as to allow a few geographical varieties. It is man who makes all these strange breeds, just as he has made such a queer, irregular, varied lot of creatures from the human stock. Withdraw once and for all man’s guiding “intelligence,” or perversity, if you choose so to call it, and all these cattle would in a few hundred years revert to one form, nearly (but not quite) the same as that they came from. So, too, the Sheep; so, too, the Pigs. And man himself, if one could poison him universally with a mind-destroying microbe, would become a beautiful, healthy, silly creature, dying at first by millions annually, and at last represented by a hundred thousand unvarying specimens, inhabiting the warm but healthy corners of the earth, aimlessly happy, free from disease, neither increasing nor decreasing in number. It is legitimate, and is a means of examining the whole problem of man’s history, to inquire whether we have reason or not to suppose that, were intelligent man thus removed arbitrarily and completely from the scene, a new “lord of the world” would arise, by normal evolutionary process. A bird, an elephant, a rat, might give rise to the new line of progressive development, and, unchecked by man, once jealous and repressive, but now down-fallen, this new stock might acquire such brains and wits as we men now boast of, and people the earth. You never can tell! But it is not the business of science to expatiate on such possibilities.

The domesticated cattle of Europe are of very ancient prehistoric origin. They are for convenience called “Bos taurus,” and seem to be derived from the huge Bos primigenius or Aurochs, the Urus of Cæsar, which was wild in Central Europe in his time, and from the Indian Bos indicus--which is represented by the Indian and African native breeds of “humped” cattle. It is, however, very difficult to trace most of man’s domesticated animals or his cultivated plants to their original wild forms and original habitation. At the Cattle Show we only see British and Irish breeds, and only those cattle bred as meat-makers--the Highland, the Welsh, the Shorthorns, the polled Angus, the South Devons, the Hereford, the Sussex, the Galloway, the Dexter. But there are other British breeds famous for their milk-producing quality, such as the Guernseys and Jerseys, whilst in Hungary, Italy, and Spain they have magnificent breeds of great size, and often with truly splendid spirally-turned horns (e.g. the Spanish), which are used for ploughing and carting, and are fattened, killed, and eaten after doing ten years’ good work. These fine creatures are not seen in England. They come nearest to the extinct Aurochs, which was, however, bigger than any of them. It, too, existed in prehistoric times in England, and we find its bones in the gravel of the Thames Valley. The last aurochs, or wild bull of Europe, was killed in Poland near the end of the seventeenth century. The wild Chillingham cattle are Roman cattle run wild. Many of these breeds and the bones of the aurochs to compare as to size may be seen in the north hall of the Natural History Museum, where I commenced a collection of domesticated breeds of cattle, sheep, horses, dogs, &c., eight years ago. Chillingham cattle are to be seen in the Zoological Gardens.

An interesting fact in this connection is that the splendid bull which is kept in half-wild herds in Spain for the purpose of “bull-fights,” is of a totally different race from that of the big, long-horned agricultural cattle. It may be seen at Cromwell-road, a specimen killed in the ring having been procured at my request and presented to the museum through the kindness of the British Consul at Seville. The Spanish fighting bull is, curiously enough, more like our Channel Island milk-producing cattle than any other. It probably came to Spain from North Africa--but there seems to be no record or history concerning it--and if there were it would probably be a fantastic invention. It seems that only the bulls of this special breed can be played with and dazzled by the matador’s red cloak. A Scotch bull was once brought by sea to Seville and introduced to the arena. He paid no attention to cloaks, red or otherwise, but always went straight for his man. It is stated that he was soon left quite alone in the ring! The native African cattle (of Indian origin) at Ujiji and in Damaraland have the biggest horns of any true Bos--as much as 13-1/2 ft. along the curve from point to point. We have to distinguish from our own cattle, for which there is no name except “Bos taurus,” for neither ox, bull, cow, heifer, nor steer will do--the other bovines--the buffaloes, the yak, and the bison--besides those great beasts the gayal and the gaur of India and the banting of Malay. All these may be seen and studied either in the Museum or the Zoological Gardens.

25. _The Experimental Method_

The observations lately made by a Chancellor of the Exchequer about an attempt to put salt on a bird’s tail remind me of my first attempt to deal experimentally with a popular superstition. I was a very trustful little boy, and I had been assured by various grown-up friends that if you place salt on a bird’s tail the bird becomes as it were transfixed and dazed, and that you can then pick it up and carry it off. On several occasions I carried a packet of salt into the London park where my sister and I were daily taken by our nurse. In vain I threw the salt at the sparrows. They always flew away, and I came to the conclusion that I had not succeeded in getting any salt or, at any rate, not enough on to the tail of any one of them.

Then I devised a great experiment. There was a sort of creek eight feet long and three feet broad at the west end of the ornamental water in St. James’s Park. My sister attracted several ducks with offerings of bread into this creek, and I, standing near its entrance, with a huge paper bag of salt, trembled with excitement at the approaching success of my scheme. I poured quantities--whole ounces of salt--on to the tails of the doomed birds as they passed me on their way back from the creek to the open water. Their tails were covered with salt. But, to my surprise and horror, they did not stop! They gaily swam forward, shaking their feathers and uttering derisive “quacks.” I was profoundly troubled and distressed. I had clearly proved one thing, namely, that my nursemaid, uncle, and several other trusted friends--but not, I am still glad to remember, my father--were either deliberate deceivers or themselves the victims of illusion. I was confirmed in my youthful wish to try whether things are as people say they are or not. Somewhat early perhaps, I adopted the motto of the Royal Society, “Nullius in verba.” And a very good motto it is, too, in spite of the worthy Todhunter and other toiling pedagogues, who have declared that it is outrageous to encourage a youth to seek demonstration rather than accept the statement of his teacher, especially if the latter be a clergyman. My experiment was on closely similar lines to that made by the Royal Society on July 24, 1660--in regard to the alleged property of powdered rhinoceros horn--which was reputed to paralyse poisonous creatures such as snakes, scorpions, and spiders. We read in the journal-book, still preserved by the society, under this date: “A circle was made with powder of unicorne’s horn, and a spider set in the middle of it, but it immediately ran out several times repeated. The spider once made some stay upon the powder.”

26. _Hypnotism and an Experiment on the Influence of the Magnet_

A more interesting result followed from an experiment made in the same spirit twenty-five years later. I was in Paris, and went with a medical friend to visit the celebrated physician Charcot, to whom at that time I was a stranger, at the Salpêtrière Hospital. He and his assistants were making very interesting experiments on hypnotism. Charcot allowed great latitude to the young doctors who worked with him. They initiated and carried through very wild “exploratory” experiments on this difficult subject. Charcot did not discourage them, but did not accept their results unless established by unassailable evidence, although his views were absurdly misrepresented by the newspapers and wondermongers of the day.

At this time there had been a revival of the ancient and fanciful doctrine of “metallic sympathies,” which flourished a hundred years ago, and was even then but a revival of the strange fancies as to “sympathetic powders,” which were brought before the Royal Society by Sir Kenelm Digby at one of its first meetings, in 1660. In the journal-book of the Royal Society of June 5 of that year, we read, “Magnetical cures were then discoursed of. Sir Gilbert Talbot promised to bring in what he knew of sympatheticall cures. Those that had any powder of sympathy were desired to bring some of it at the next meeting. Sir Kenelm Digby related that the calcined powder of toades reverberated, applyed in bagges upon the stomach of a pestiferate body, cures it by several applications.” The belief in sympathetic powders and metals was a last survival of the mediæval doctrine of “signatures,” itself a form of the fetish still practised by African witch-doctors, and directly connected with the universal system of magic and witchcraft of European as well as of more remote populations. To this day, such beliefs lie close beneath the thin crust of modern knowledge and civilisation, even in England, treasured in obscure tradition and ready to burst forth in grotesque revivals in all classes of society. The Royal Society put many of these reputed mechanisms of witchcraft and magic to the test, and by showing their failure to produce the effects attributed to them, helped greatly to cause witches, wizards, and their followers to draw in their horns and disappear. The germ, however, remained, and reappears in various forms to-day.

Thirty years ago some of the doctors in Paris believed that a small disc of gold, or copper, or of silver, laid flat on the arm could produce an absence of sensation in the arm, and that whilst one person could be thus affected by one metal another person would respond only to another metal, according to a supposed “sympathy” or special affinity of the nervous system for this or that metal. This astonishing doctrine was thought to be proved by certain experiments made with the curiously “nervous” (hysterical) women who frequent the Salpêtrière Hospital as out-patients. That the loss of sensation, which was real enough, was due to what is called “suggestion”--that is to say, a belief on the part of the patient that such would be the case, because the doctor said it would--and had nothing to do with one metal or another, was subsequently proved by making use of wooden discs in place of metallic ones, the patient being led to suppose that a disc of metal of the kind with which she believed herself “sympathetic” was being applied. Sensation disappeared just as readily as when a special metallic disc was used.

The old hypothesis of the influence of a magnet on the human body was at this time revived, and Charcot’s pupils found that when a susceptible female patient held in the hand a bar of iron surrounded by a coil of copper wire leading to a chemical electric cell or battery nothing happened so long as the connection was broken. But as soon as the wire was connected so as to set up an electric current and to make the bar of iron into a magnet, the hand and arm (up to the shoulder) of the young woman holding the bar, lost all sensation. She was not allowed to see her hand and arm, and was apparently quite unconscious of the thrusting of large carpet-needles into, and even through, them, though as long as the bar of iron was not magnetised she shrunk from a pin-prick applied to the same part. I saw this experiment with Charcot and some others present, and I noticed that the order to an assistant to “make contact,” that is to say, to convert the bar of iron into a magnet, was given very emphatically by Charcot, and that there was an attitude of expectation on the part of all present--which was followed by the demonstration by means of needle-pricking that the young woman’s arm had lost sensation, or, as they say, “was in a state of anæsthesia.”

Charcot went away saying he should repeat the experiment before some medical friends in an hour or two. In the meantime, being left alone in the laboratory with my companion as witness, I emptied the chemical fluid (potassium bichromate) from the electric battery and substituted pure water. It was now incapable of setting up an electric current and converting the bar into a magnet. When Charcot returned with his visitors, the patient was brought in, and the whole ritual repeated. There was no effect on sensation when the bar was held in the hand so long as the order to set the current going, and so magnetise the bar, had not been given. At last the word was given, “Make!” and at once the patient’s arm became anæsthetised, as earlier in the day. We ran large carpet-needles into the hand without the smallest evidence of the patient’s knowledge. The order was given to break the current (that is, to cease magnetising the bar), and at once the young woman exhibited signs of discomfort, and remonstrated with Charcot for allowing such big needles to be thrust into her hand when she was devoid of sensation! My experiment had succeeded perfectly.

It would not have done to let Charcot, or anyone else (except my witness) know that when the order “Make” was given, there was no “making,” but that the bar remained as before un-magnetised. The conviction of everyone, including Charcot himself, that the bar became a magnet, and that loss of sensation would follow, was a necessary condition of the “suggestion” or control of the patient. It was thus demonstrated that the state of the iron bar as magnet or not magnet had nothing to do with the result, but that the important thing was that the patient should believe that the bar became a magnet, and that she should be influenced by her expectation, and that of all those around her, that the bar, being now a magnet, sensation would disappear from her arm. With appropriate apologies I explained to Charcot that the electric battery had been emptied by me, and that no current had been produced. The assistants rushed to verify the fact, and I was expecting that I should be frigidly requested to take my leave, when my hand was grasped, and my shoulder held by the great physician, who said, “Mais que vous avez bien fait, mon cher Monsieur!” I had many delightful hours with him in after years, both at the Salpêtrière and in his beautiful old house and garden in the Boulevard St. Germain.

There are few “subjects” in this country for the student of hypnotism to equal the patients of the Salpêtrière and other hospitals in France--and very few amongst those who read, and even write, about “occultism” and “super-normal phenomena” know the leading facts which have been established in regard to this important branch of psychology. The study of the natural history of the mind, its modes of activity, and its defects and diseases is of fundamental importance--but its results are often either unknown or greatly misunderstood by those who have most need of such knowledge, namely those who, mistaking the attitude of an ignorant child for that of “a candid inquirer,” try to form a judgment as to the truth or untruth of stories of ghosts, thought-transference, spirit-controls, crystal-gazing, divining-rods, amulets, and the evil eye.

27. _Luminous Owls and Other Luminous Animals and Plants_

A correspondent lately described in a letter to a London newspaper what he believed to have been “a luminous owl,” which was seen flying about at night in Norfolk. He mentioned the well-known fact that the dense greasy patch of feathers on the breast of the heron is said to be luminous by many trustworthy observers. It is very probable that it was some carnivorous or fish-eating bird, which was thus seen in a luminous condition at night. The occurrence is much more in accordance with known facts than most people would suppose to be the case. Light, even strong light, is produced by many natural objects without the accompaniment of heat. We usually expect not merely fire where there is smoke, but heat--in fact, great heat, where there is light or flame. Yet there are many instances to the contrary, and the word “phosphorescence” is used to indicate a production of light without heat in reference to the fact that phosphorus is luminous, even when covered with water, although no appreciable heat accompanies the light such as we are accustomed to observe in ordinary “combustion” or burning.

There is more than one kind of phosphorescence. We separate the phosphorescence which is due to the oxidation of peculiar fatty matters in the bodies of plants and of animals (such as glow-worms) from that which is caused by the breaking or heating of crystals (white arsenic and apatite), or by longer or shorter exposure to the sun’s rays (luminous paint), or by radio-activity, or by electrical discharges in vacuum tubes.

The “luminous owl” of the above-mentioned correspondent and the luminous breast of the heron probably owe their strange appearance to the birds having smeared themselves with phosphorescent carrion or dead fish, the luminosity of which is due to bacteria. The simplest case of phosphorescence in living things is that of the almost ubiquitous phosphorescent bacteria, minute microbes like those which cause putrefaction. They can be obtained and cultivated from almost any sample of sea water. A thin slice of meat placed in a shallow dish of salt water, so as to be barely covered by the liquid, will in cool, damp weather, almost certainly become covered with the growth of this phosphorescent germ and appear brilliantly luminous. The populations of seaside towns have often been terrified by all the meat in the butchers’ shops suddenly becoming thus phosphorescent. The growth may be cultivated in flasks of salt broth. I have prepared such flasks, which, when shaken so as to introduce oxygen, give out a heatless blaze of light of a greenish colour, brilliant enough to light up a room. I once found a bone in a dog’s kennel which was brilliantly phosphorescent owing to this bacterium. I kept it for several days and showed it to Huxley as well as to other friends. A certain kind of phosphorescent bacteria are parasitic in the blood of sandhoppers, causing a disease which kills them. The diseased sandhoppers shine like glow-worms. I have found them abundantly on the sea shore near Boulogne and near Trouville, but not yet on the English coast. The bacteria can be seen with the microscope and inoculated from diseased luminous sandhoppers into healthy ones by using a needle to prick first the diseased and then the healthy creature.

The animals of the sea are often provided with secreting organs, producing a fatty body which can be oxidised and made luminous at the pleasure of the animal. Thus many marine worms and minute sea-shrimps give out brilliant flashes of light. Jelly-fish of many kinds, and the minute noctiluca, no bigger than a pin’s head, and the three-horned animalcule Ceratium tripos are the usual cause of the phosphorescence of the sea on our own coast. Deep-sea fishes are provided with large phosphorescent discs or plates on the surface of the body, which are sometimes furnished with lenses like a bull’s-eye lantern. Glow-worms and fire-flies and some tropical beetles are examples of insects which have fatty phosphorescent organs which they can illuminate (oxidise) at pleasure, under the control of the nervous system. Some of the West Indian phosphorescent beetles are remarkable for having “lights” of two different colours. In the marshes around Mantua the fire-flies are so abundant at the end of June that the air for miles is full of them, and the sight so extraordinary and beautiful as to be worth a long journey to see. I have seen fire-flies as far north as Bonn on the Rhine. Once I was nearly upset by a horse shying at a glow-worm on a bank in Worcestershire. Some moulds and well-grown toadstools are phosphorescent, and a phosphorescent earthworm, a peculiar species, now well known, was first of all discovered in the South of Ireland by the late Professor Allman. In the autumn I have often picked up the phosphorescent centipede, which is remarkable for the fact that the phosphorescent material is a kind of slime which exudes from the body--the creature leaving thus a luminous trail behind it as it crawls. The piddock, or pholas--a boring sort of mussel--has brilliant phosphorescent glands, and the boys at Naples love to munch these shell-fish at night, and then to alarm the passer-by by opening their mouths, and showing a brilliant green light within. Cases are recorded, but not recently, of persons suffering from tuberculosis becoming phosphorescent; a possible, but certainly a rare, occurrence. Animal and vegetable phosphorescence is varied in colour. The light emitted is blue-green, green, yellow, orange, and even red in different cases. It is always due to the oxidation of a separate fatty chemical body, which can in many instances be extracted, then dried, and subsequently made luminous by moistening with ether, in consequence of which oxidation by the oxygen of the atmosphere is facilitated.

28. _Reminiscences of Lord Kelvin_

The late Lord Kelvin was one of the most fascinating personalities in the learned world. He uttered with a delightful simplicity the thoughts, however romantic and fanciful, which bubbled up in his wonderful brain. It was because he was so much of a poet that he was so great a man of science. Atoms and molecules and vortices, and the vibrations and gyrations of ether, and “sorting demons” were all pictured in his mind’s eye, and used as counters of thought to give shape and the equivalent of tangible reality to his conceptions. By such conceptions he was able to present to himself and his listeners the complex mechanisms of crystals, of liquids, of gases, of electrical and magnetic currents, and the endless astounding proceedings of rays of light unsuspected by the ordinary man.

I think the last occasion on which he spoke in public was after Sir David Gill’s brilliant address to the British Association at Leicester last August. Lord Kelvin was sitting close to me on that occasion, and I noticed that he never moved his gaze from the speaker. He followed Sir David’s account of stars, whose distance is stated by the number of years it takes for their light to travel to this earth, like an enraptured schoolboy, and cheered when the evidence for the existence of two great streams of movement of the heavenly bodies, in opposite directions, going no one knows whither, coming no one knows whence, was sketched to us by the lecturer. In proposing a vote of thanks to Sir David Gill, Lord Kelvin burst into a sort of rhapsody, in which, with unaffected enthusiasm, he declared that we had been taken on a journey far more wonderful than that of Aladdin on the enchanted carpet; we had been carried to the remotest stars and well-nigh round the universe, and brought back safely to Leicester on the wings of science, and the most marvellous thing about it all was that it is true!

A few weeks before this Lord Kelvin was at the dinner in celebration of the jubilee of the foundation of the Chemical Society. In the speech which he then made he referred to the painful accident of a year or so ago which we had all so much regretted, when he had burnt his hand accidentally in some experiments with phosphorus, and had had to carry his arm in a sling for some weeks. “Lord Rayleigh, the president of the Royal Society,” he said, “has just told us how, as a boy, he gave proof of his devotion to chemical science by burning his fingers with phosphorus--but I think my devotion must be considered greater than his, for I burnt my fingers very badly with phosphorus only last year, when I was 83 years old. It was at the end of April. My friends said I was old enough to know better, and it should have happened, not at the end of April, but on the first day, of that month.” Lord Kelvin was associated in work in the sixties and seventies with another splendid man, Tait, of Edinburgh, who, besides being a great professor of “Natural Philosophy,” and joint author of the celebrated treatise known as _Thomson and Tait_, was a great athlete--a golfer of the first class, a first-rate billiard player, and a wise lover of good ale, which he drank and gave to his friends to drink, whilst he discoursed as few, if any, to my knowledge, can now do, of things philosophical, mathematical, and humane.

29. _The So-called Jargon of Science_

It is often discussed as to whether science fails to obtain the attention of the public and to excite intelligent interest, owing to the obscure language which lecturers and writers use when attempting to expound scientific views and discoveries to “the ordinary man,” or whether the fault lies with the “ordinary man” himself, who is too frivolous to bother about following carefully the words addressed to him, and, moreover, has never learnt even the A B C of science at school. It is certainly the case, as Professor Turner, the Oxford professor of astronomy, has pointed out, that a popular lecturer could tell his auditors a good deal more in an hour if they already had the elements of his subject at their fingers’ ends than he can under the existing state of neglect of school education in the natural sciences. That, however, seems to be obvious enough, and does not touch the real question.

I have had a long experience, both in lecturing myself and in assisting in the training of others to lecture and also to inform the uninstructed public by means of museum-labels and popular notes. It seems to me that there are a large number of men who, even though capable of expressing themselves clearly under usual circumstances, yet fail to do so when trying to expound or to teach, in consequence of three distinct faults, any one of which is enough to render their discourse or writing hopelessly obscure to “the man in the street.” These are, first, a kind of pride in using special terms and modes of expression which infatuates the lecturer or writer, and leads him, without reflection, to an attitude of mind expressed by saying, “That is the correct statement about this matter, short and true. If you don’t understand it, there are others who can. You can leave it alone; it is not worth my while to spend time and trouble to explain further; it is for you to give yourselves the trouble to find out what I mean.” The second fault is a real incapacity (which occurs in many learned men) to realise the state of mind of the uninstructed man, woman or child who eagerly desires to be instructed: this is want of imagination and want of sympathy. There is no cure for those who fail as teachers for either of these two reasons.

The third fault is much more widely at work, and the most kindly sympathetic lecturers and writers--but more especially lecturers--often suffer from it and could easily amend their practice. It consists in the attempt to tell the audience or reader too much--vastly too much--in the limit of one hour, or within the space of a few lines or pages. This failure is well-nigh universal. I have heard a distinguished discoverer, an eloquent and able man, try to tell a completely ignorant audience in one hour the results of years of experiment and work by many men on the electrical currents observed in nerves. The audience did not know what is meant by an electrical current, nor anything about nerves, nor a single one of the technical terms necessarily used by the lecturer. The task was an impossible one. In six lectures it might have been accomplished, and great delight and increase of understanding afforded to the listeners instead of perplexity and a sense of their own incapacity and the hopeless obscurity of science. That, I am convinced, is the real trouble, viz., the attempt to tell too much in a short time, the failure by the lecturer to arrange his exposition in a series of well-considered, definite steps, each exciting the desire to know more, and each given sufficient time and experimental illustration or pictorial demonstration to lodge its meaning and value safely and soundly in the tender brain of the ignorant but willing listener. I am convinced that there is in very many lecturers a tendency to try to crowd and compress into one lecture what should occupy ten--if the willing and intelligent but ignorant listener is to feel happy and is really to understand what is said and done for his instruction. A special difficulty also arises from the fact that the lecturer often feels himself called upon to address and to say something to those among the audience who already know a good deal about his subject, as well as to make things clear to those who are absolute novices.

Some people have made this discussion the opportunity for attacking on the one hand the English language, and on the other the use of special names applied by men of science to special things and special processes. We cannot at once change the English language, even did we wish to do so. But the creation of special names to distinguish things not distinguished from one another in common speech is a necessity. It cannot be avoided. It is mere impatience and temper to call the names and terms which are necessary as counters of thought “jargon.” No doubt there may be in some lecturers and writers a tendency to excessive use of special terms and names, but the real trouble in the matter arises from the too rapid thrusting of a large number of such unfamiliar words upon an untrained audience. If new words are introduced in moderation they can be assimilated. They cannot be dispensed with altogether. A correspondent lately complained to me that I wrote of the minute creature which causes the sleeping sickness as a Trypanosome, whereas, had I called it “a blood-parasite” he would have known what I meant, and been able to follow my statement more easily. I am sorry to say that I cannot agree with him. There are many kinds of blood-parasites; there are the worms known as Filariæ, there are the vegetable microbes known as bacteria and bacilli and spirilla, and there are minute creatures of an animal nature called pyroplasma and trypanosoma (beside some others). These must be distinguished from one another if we are to understand anything about the causation of disease by microbes. It would be mere muddling and confusion to simply call them all by the same name, simply “blood parasite.” That would cause the same sort of confusion as would occur if the Smiths or Browns of our acquaintance had no Christian names by which we can separate each member of the class from the others and assign to him his own special qualities, opinions, and property. What some people call “scientific jargon” is assuredly not a thing to be proud of or to mouth with a sense of superiority. Nevertheless, it is absolutely necessary, and must be introduced gently and considerately to the stranger who can and will, if reasonably handled, appreciate the immeasurable advantage of having distinct words to signify distinct things. That, after all, is an elementary feature in all language. And just as the “jargon” of a game, a sport, or a profession has a fascination for those who use it, and forms a bond of union or special understanding between them, so inevitably does the jargon of a branch of science flourish in the thought and on the lips of those who devote themselves to that branch, and bind them in a sort of freemasonry. We do not expect cricketers or golfers to talk in plain English; why should we expect chemists or naturalists to do so? After all, it is a question of moderation and of gradually increasing the dose. The beginner must not be terrified by an array of outlandish words.

30. _Rats and the Plague_

Rats! Who said rats? That is an important question, because the word means different things to different people. To some persons “rats” means simply “nonsense”! To Sir James Crichton Browne it means the devastator of stores and the dread carrier of bubonic plague. To the naturalist it means a group or natural cohort of small mammals similar to our common rat and mouse, representatives of which are found in every quarter of the globe and in almost every island of the sea. The distinct “kinds” or “species” are numbered by the hundred. They are extraordinarily alike, and can only be distinguished and classified into proper “species” by careful examination and measurement. Mr. Oldfield Thomas, of the Natural History Museum, has made a special study of them. To give an idea of his work, it may be mentioned that ninety different names had been given by previous writers to as many apparently distinct kinds of rat occurring in India. But by careful measurement and study of the relations to one another of these rats, Mr. Thomas has reduced the number of really distinct Indian species of rats and mice (for a mouse is only a smaller rat) to nineteen. What we call in English water-rats, or water-voles, field-voles, and such little foreign beasts as the lemming and the hamster, are very close to rats in appearance, but are separated on account of clear differences of structure from true rats and mice.

At a meeting in London the total destruction of “rats” was advocated. Whether it was affirmed at the meeting, or was merely an error of those who wrote and commented on the matter afterwards, I do not know, but it was very generally stated in this connection that the old Black rat (known to naturalists as Mus rattus) is quite extinct in England, and that its place has been taken by the Norwegian, or Grey rat (Mus decumanus), also called the Hanoverian rat, because it became noticeable by its abundance in this country at the time of the accession of the Hanoverian kings. The Black rat is not extinct in England, not even very rare. Mr. Stendall lately sent me specimens caught in his warehouse in the City of London, where they are abundant. In many localities, _e.g._ Great Yarmouth, and in isolated dwelling-places they occur, and even outnumber the Norwegian rat. A most important and remarkable fact is that the rats which infest ships are often all Black rats. The Black rat, or Alexandrine rat (as Mr. Thomas calls it), lives in our houses, in the roof, in recesses of woodwork. It is a house rat, whereas the Grey, or Norwegian rat, lives in the sewers and the banks of ditches, and only comes up into the basement of houses through defective building. The Grey rat has driven out the water-voles from many river banks near towns, just as he has to a great extent taken the place of the Black rat in houses where the kitchen and food stores are close to and in communication with the sewer!

The Black rat cannot be really distinguished by his blackness. That is why some naturalists call him the Alexandrine rat, so as to avoid a misleading implication. He is often of a bright yellowish-brown colour along the back--with longer dark-brown hairs and a good deal of grey elsewhere--quite like the Norwegian or Grey rat in colour. At the same time he is often blackish, and frequently very black. The colour of all these kinds of rats and mice can vary, according to the conditions and colour surroundings in which they live. Black, white, sandy-brown, or a mixture of spots of all three colours, or a uniform “mouse-brown” tint, are (as most boys know) the possibilities revealed by allowing them to breed in captivity. Nature selects accordingly the particular tint which affords protection from observation by enemies in a given locality.

The real distinction between the Black (Alexandrine) rat and the Grey (Norwegian) rat is that the Black rat is smaller, has a tail longer than its body (125 per cent.), and long and wide ears, which stand out from the head. The Grey (Norwegian) rat is a larger, heavy-bodied rat, with a tail shorter than its body (90 per cent.), and short ears. Both these rats are common in India, but there is a third kind, which is the commonest of the three in Calcutta, and is probably the one most concerned in the dissemination of plague. It differs in some definite features from both the Black rat and the Grey rat, although it is very much like the latter in general appearance. It is called Nesokia Bengalensis, or Mole-rat. It is a big rat--its tail is only 70 per cent. the length of its body; the pads on the soles of its feet differ from those of the two other rats; its fur is thin and bristly, and when it is put into a cage it erects its bristles and spits! It is, like the Black rat, a stable and granary rat, and makes burrows in which it stores grain.

The rats of Calcutta have been carefully studied lately by Dr. Hossack, in consequence of their connection with the bubonic plague. In the older native parts of Calcutta, the Mole rat is twice as common as the Norwegian Grey rat, and the Black rat not so abundant as the latter. In the central European part of the town the Grey rat is commoner than the Mole rat--because, apparently, the better-built houses do not afford such facilities for burrowing. The Black rat is here also by a good deal the most uncommon of the three. All these rats suffer from the plague, die from it, and the fleas which lived in their fur leave them as they get cold, and make their way on to human beings, whom they consequently infect with the plague bacillus. This has now been quite conclusively proved by the Indian doctors charged by Government with the study of the causes of the plague. The plague bacillus--a minute, rod-like organism, which grows in the blood and lymph, once it has effected a lodgment, and there produces deadly poison--was discovered some fourteen years ago, but it is only recently that the plague bacillus has been shown to live in the intestine of the flea, which sucks it up with the blood or other fluids of the rat on which it lives. The flea, which readily goes to man, does not suffer from the plague bacilli which it has gorged, but conveys them to man either by its bite or by its excrement.

This being so, it becomes important to know all about the fleas of rats. Quite unexpected facts have been discovered in regard to them. In Europe a very large flea is found on the grey and the black rat. This kind has not, I believe, ever been found on human beings or been known to bite them. But in India, in the Philippines, and in the ports of the Mediterranean, this northern rat-flea is rare, and its place is taken by a smaller and more actively vagrant flea, which Mr. Charles Rothschild (who is the great authority on fleas) found upon several different kinds of small animals in Egypt. He named it “Pulex cheopis.” This is the flea (and not our big northern rat-flea) which acts as the carrier of plague-germs from rats to man in India. It appears from experiments that the common flea of man (Pulex irritans) and the cat-and-dog flea (Pulex felis), as well as the big northern rat-flea (Ceratophyllus fasciatus), can harbour the plague-bacillus if fed on plague-stricken animals, but there are no observations to show (as there are about the “Cheops flea”) that they pass habitually from man to rats and rats to men.

It is happily so long (200 years) since we had a real outbreak of plague in Europe that we are still in doubt as to whether the Grey rat or the Black rat is the more susceptible to the disease--and what flea, if any, acts, or has acted, as the carrier from rat to man in this part of the world. The suggestion has been made that the Grey Norwegian rat takes plague less easily than the Black rat, or than the Indian Mole-rat (Nesokia), and that the multiplication of the Grey rat in England and France and consequent decrease in Black rats, is, therefore, an advantage, so far as plague is concerned. Possibly with the Grey rat has come the big rat-flea, which does not attack man as does the Cheops flea. The disappearance of plague in Western Europe seems to correspond in date with the arrival of the Grey rat. But, on the other hand, an alteration in the character of our houses and their greater “accommodation” for the new rat rather than the old black species may account both for the increase of the latter and for the absence of dirt and vermin in the dwelling-rooms and bed-chambers which formerly enabled the plague-bacillus to flourish amongst us, and to reach the human population--as it does now in India and China. All this shows how necessary it is to have accurate true knowledge of such despised creatures as rats and fleas, if we are to live in great crowded cities closely packed together. And it should also make us try to gain further knowledge as to these creatures, so that we may form a reasonable anticipation of the consequences we are bringing down on our heads when we set about exterminating this or that race of animals. We are not yet sure that the Norwegian Grey rat is not a blessing in disguise.

31. _Ancient Temples and Astronomy_

Janssen, the French astronomer, who died about the same time as Lord Kelvin, acquired celebrity by his discovery of a method for seeing and studying the great flames or prominences which surround the sun. The glare of the great fiery ball is such that the eye is blinded in ordinary circumstances to the light of these prominences. They were only known from their coming into view during the total eclipse of the sun’s disc by the moon. Then they were seen as a great fringe of pointed, tongue-like flames around the darkened disc. But at other times no use of smoked glass or telescope could bring them into view. Janssen went to India in 1868 to study these prominences of the sun during the total eclipse of that year. His purpose was to examine with a spectroscope the light given out by the prominences. The day after the eclipse Janssen found that he could still examine the prominences and make out their shape and the chemical elements present in them by looking at them through the spectroscope, although the sun’s disc was now uncovered, and it was impossible to see the prominences with the unaided eye or with the telescope.

A young English astronomer, hundreds of miles apart from Janssen, on the same day, Aug. 18, 1868, made the same discovery in the same way, independently. The English astronomer was Norman Lockyer, and the French Academy of Sciences caused a medal to be struck in commemoration of this discovery. The medal is before me as I write. It shows the heads of Janssen and of Lockyer side by side, as they were forty years ago.

Each has carried on his researches and discoveries with unabated vigour since that happy conjunction. Sir Norman Lockyer has for many years added to his constant study of the sun, fixed stars, and nebulæ by means of the spectroscope and photographic record of spectra, an inquiry into the evidence afforded by astronomical facts first as to the age of Greek and Egyptian temples, and latterly as to that of the mysterious avenues and circles of stones (such as Stonehenge) scattered about the British Islands, of the history and use of which we have only vague traditions and no actual records. These stone circles and avenues are very numerous in Great Britain. The chief are Stonehenge, Avebury, and Stanton Drew in the middle South of England; the Hurlers, Boscawen-Un, Tregaseal, the Merry Maidens, and the Nine Maidens in Cornwall; Merrivale Avenue and Fernworthy Avenue in Devon; many circles in Aberdeenshire, in Cumberland, Derbyshire, and Oxfordshire, as well as monuments of the same kind in Wales. Sir Norman Lockyer has obtained measurements of most of these and plans showing the relations of the principal lines of their ground plan to the points of the compass, and so to the position occupied by the sun and by certain stars on given days of the year at the rising or setting of those heavenly bodies. It may well be asked what is Sir Norman’s object in doing this?

The explanation is as follows: The builders of Christian churches in Europe have, as a rule, set out the ground plan of the church shaped like a Latin cross, so that the arms of the cross run north and south--the head points to the east, or Orient, and the base to the west. In consequence of this custom the word “orientation” has come into use, to signify the direction purposely given to the main length of a temple or church. Now it appears that many, if not all, ancient temples (including the ancient stone circles and avenues of Britain) were purposely so “oriented” by their builders that a particular star, or the sun itself, should at a fixed day and hour in the year be seen during its movement across the heavens through an opening in the building especially designed for this purpose, so as to allow the light of the star to fall into the most sacred part of the temple, the “Naon,” or Holy of Holies. At the moment of its appearance special ceremonies were performed by the priests and worshippers in the temple. The temple was dedicated to and carefully “oriented to” that particular star. Thus, in ancient Greece, the Pleiades, Sirius (the dog star), Spica, and other stars were thus used; in Egypt, Capella, Canopus, and Alpha Centauri; in Britain, Arcturus, as well as those used by the Greeks.

These temples were really astronomical observatories, and were meant always to remain “oriented” to their special star, which must, if the earth were steady in its position, although spinning like a top, and also circling round the sun, duly appear each year at the expected day and minute in the special “window” or aperture designed so as to allow the star--then, and then only--to shine into the temple. But the astronomers have discovered that the earth is not steady! It “wobbles” very slowly and regularly as a top wobbles. The position of the axis of rotation--corresponding in position to the stem of a top--does not remain one and the same, but is pulled aside by the attraction of the sun and moon, and moves round as one may often see in the spinning of a top. The earth takes about 26,000 years for its poles to complete the cycle of its wobble. Moreover, in addition to this, there is the fact that the earth’s axis (stem of the top) is not nearly upright, but inclined at a considerable angle (23 deg.) to the horizontal or plane of its orbit round the sun, and that this inclination very slowly changes, in addition to the wobbling movement. The amount and rate of these changes in the inclination of the axis of the earth have been definitely ascertained by astronomers.

I mention the nature of these movements because they clearly enough must upset altogether the desired result of the orientation of temples. The last-mentioned slow increase of obliquity affects solar temples chiefly, and the more rapid wobbling affects the star temples--both to such a degree that temples oriented two or three thousand years ago are now quite out of line, and no longer “catch,” so to speak, their particular star or the sun on the appointed day. They no longer point truly, because the “pitch” of the earth has altered since they were set.

The next point is that astronomers are able to calculate with surprising accuracy from other observations how much exactly at this moment the “pointing,” or “alignment,” must be “out” as compared with a thousand, fifteen hundred, two, three, four, or more thousand years ago. Accordingly, if you know the star to which an ancient temple was set or aligned, the day of the solar year which was the festival or critical moment of the appearance of the star in the sacred aperture--and how much the temple is to-day out in its pointing, that is to say, the exact amount of swinging which would bring the temple back into its original relation to the star--you have a means of measuring the age of the temple; you have a measure of the time which has elapsed since it acquired this amount of departure from correct orientation. Astronomy tells you how much it must get out of line in every hundred years.

Mr. F. C. Penrose, F.R.S., investigated this matter in regard to several Greek temples; others besides Sir Norman Lockyer have written on the aberration and calculable age of Egyptian temples. It has, for instance, actually been found that the temple of Ptah was aligned to the sun in the year 5200 B.C. The alignment is no longer correct, and it appears that the Egyptians themselves discovered that some of their most ancient temples had lost correct alignment, and erected new and corrected buildings in connection with them, and re-dedicated them. Now Sir Norman is making a vigorous effort to procure all the possible measurements and indications concerning the prehistoric circles and avenues of Britain before it is too late. They are being more and more rapidly destroyed. Stonehenge has been carefully measured and its present alignment determined by various surveyors. Its age is discussed by Sir Norman Lockyer in an interesting book, but we may soon expect a further discussion of the whole subject of these prehistoric British monuments from his pen. In some cases, as in that of Stonehenge, the relation of the temple to the sun is obvious and confirmed by tradition and existing custom. But in many cases investigation is rendered very difficult by the absence of any immediate indication of what precisely is the heavenly body to which the temple was at its foundation oriented.