Popular Science Monthly/Volume 45/August 1894/Popular Miscellany

From Wikisource
Jump to: navigation, search


Prof. William Dwight Whitney.—Prof. William Dwight Whitney, of Yale College, the foremost and greatest American philologist, died June 7th, in the sixty-eighth year of his age. He was born at Northampton, Mass., in 1827; was graduated from Williams College in 1845; after spending three years in the Northampton Bank, he went to Lake Superior in 1849 as an assistant in botany and ornithology in the United States Geological Survey. Having begun the study of Sanskrit, he continued it at Yale College, under Prof. Salisbury, for one year after his return from this work. He then studied in Germany, under Prof. Weber, of Berlin, and Prof. Roth, of Tübingen. Before he was thirty years of age he had edited, with Prof. Roth, the Atharda Veda, and had become Professor of Sanskrit in Yale College. He prepared a series of German text-books which have sustained an excellent reputation, and continued the publication of Sanskrit books in rapid succession, crowning the series with a Sanskrit grammar in English and German, and a book on the Roots, Verb Forms, and Primary Derivatives of the Sanskrit Language, which appeared in 1879. These works, says the Nation, "are based, not on the dicta of predecessors, but upon actual observation of the facts of the language, which are subjected to masterly classification and vigorously scientific induction." He wrote frequent and valuable essays on Hindu astronomy, phonetics, comparative grammar, and mythology; Oriental religions and literature, and the origin and nature of languages; and delivered lectures at the Smithsonian and Lowell Institutions, out of which grew the volume on the Life and Growth of Language of the International Scientific Series and his book on Language and the Study of Language, which have been widely translated. Other essays were embodied in the book. Oriental and Linguistic Studies. He was an important contributor to the Sanskrit-German Lexicon published by the Imperial Academy of Russia, 1852-'75; was a member and officer of the American Oriental Society for fifty-one years, and its president after 1884; was first president of the American Philological Association and a frequent contributor to its Transactions and Proceedings; was editor-in-chief of the Century Dictionary, and was a member of numerous learned societies abroad. A biographical sketch of Prof. Whitney was given, with portrait, in The Popular Science Monthly for May, 1879 (Vol. XV).


Women and Education in the South. A valuable circular published by the United States Bureau of Education is that on Southern Women in the Recent Educational Movement in the South, which has been prepared by the Rev. A. D. Mayo, and embodies a review of what he has seen and learned during twelve years that he has been engaged in the service of education in the South, in which he has come in contact with every variety of school, both races, and all classes. The essay presents three main divisions, relating respectively to Southern schools for the education of girls; the work of Northern and Southern women in the superior schools for colored youth; and the common school; in all of which departments the women of the South are becoming every year more broadly and vitally interested. To the principal paper are added in an appendix several essays, originally presented as lectures or magazine articles, bearing on the subject of education in the South.


Cause of the Migration of Birds.—Concerning the reason of birds migrating. Canon Tristram observed in the British Association that observation has brought to light many facts which seem to increase the difficulties of a satisfactory answer to the question. The autumnal retreat from the breeding quarters might be explained by a want of sufficient sustenance as winter approaches in the higher latitudes, but this will not account for the return migration in spring, since there is no perceptible diminution of supplies in the winter quarters. The northward movement of all the others must be through some impulse not yet ascertained. In many other instances it is not dependent on the weather at the moment. This is especially the case with sea birds. Prof. Newton observes they can be trusted as the almanac itself. Foul weather or fair, heat or cold, the puffins—Fratercula arctica— repair to some of their stations punctually on a given day, as if their movements were regulated by clockwork. In like manner, whether the summer be cold or hot, the swifts leave their summer home in England about the first week in August July occasional stragglers ever being seen after that date. To say that migration is performed by instinct is no explanation of the marvelelous faculty; it is an evasion of the difficulty. The sense of sight can not guide birds which travel by night, or span oceans or continents in a single flight. In noticing all the phenomena of migration there yet remains a vast untilled region for the field naturalist. What Prof. Newton terms the sense of direction, unconsciously exercised, is the nearest approach yet made to a solution of the problem. He remarks how vastly the sense of direction varies in human beings, contrasting its absence in the dwellers in towns compared with the power of the shepherd and the countryman, and, infinitely more, with the power of the savage or the Arab.


Chemical Constitution and Color.—A curious side light, says Prof. James Emerson Reynolds, seems to be thrown on the nature of the elements by the chemico-physical discussion of the connection existing between the constitution of certain organic compounds and the colors they exhibit. We may take it as an established fact that a relation exists between the power which a dissolved chemical compound possesses of producing the color impression within our comparatively small visual range, and the particular mode of grouping of its constituent radicals in its molecule. Further, the reality of this connection will be most freely admitted in the class of aromatic compounds—that is, in derivatives of benzene, whose constituents are so closely linked together as to exhibit quasi-elemental persistence. If, then, the possession of what we call color by a compound be connected with its constitution, may we not infer that "elements" which exhibit distinct color, such as gold and copper, in thin layers and in their soluble compounds, are at least complexes analogous to definitely decomposable substances? This inference, while legitimate as it stands, would obviously acquire strength if we could show that anything like isomerism exists among the elements; for identity of atomic weight of any two chemically distinct elements must, by all analogy with compounds, imply dissimilarity in constitution, and therefore definite structure, independently of any argument derived from color. Now, nickel and cobalt are perfectly distinct elements, as we all know, but, so far as existing evidence goes, the observed differences in their atomic weights (nickel, 58·6; cobalt, 58·7) are so small as to be within the range of the experimental errors to which the determinations were liable. Here, then, we seem to have the required example of something like isomerism among elements, and consequently some evidence that these substances are complexes of different orders; but in the cases of cobalt and nickel we also know that in transparent solutions of their salts, if not in thin layers of the metals themselves, they exhibit strong and distinct colors—compare the beautiful rosy tint of cobalt sulphate with the brilliant green of the corresponding salt of nickel. Therefore, in exhibiting characteristically different colors, these substances afford us some further evidence of structural differences between the matter of which they consist, and support the conclusion to which their apparent identity in atomic weight would lead us. By means of such side lights we may gradually acquire some idea of the nature of the elements, even if we are unable to get any clew to their origin other than such as may be found in Crookes's interesting speculations.


The Camphor Tree.—While camphor was formerly produced in Sumatra, Borneo, and other parts of the East Indies, all now known to the trade comes from Japan and Formosa. The camphor tree is a large evergreen of symmetrical proportions, somewhat resembling a linden. It bears a white flower which ripens into a red berry. Some of the trees are fifteen feet in diameter and live to a great age. A group of trees in the province of Toosa, about a century old, are estimated to be equivalent to about forty thousand pounds of crude camphor. The camphor is extracted from chips taken from the roots or from the stem near the root, the wood yielding about five per cent of camphor, and the root a larger proportion. The annual export of Japan camphor averages about five million pounds. The forests in Japan owned by the people are now almost denuded of timber, but the Government still possesses large woods of camphor trees, which, it is estimated, will maintain a full average supply of the gum for the next twenty-five years. Plantations of young trees are also making and well taken care of; and although camphor has not hitherto been extracted from trees less than seventy or eighty years old, it is expected that under the present intelligent management equally good results may be realized in twenty-five or thirty years. The Japanese Department of Forests, which has the control of these woods, is under good management.


Constitution of the Ether.—Assuming that the elastic solid theory of the ether has failed, Mr. R. T. Glazebrook thinks that the properties of the ether which would lead to the equations that represent the laws of the transmission of light, may be found in the labile ether of Lord Kelvin. This is an elastic solid, or quasi solid incapable of transmitting normal waves. Such a medium would collapse unless of infinite extent, or else fixed at its boundaries. A soap bubble affords in two dimensions an illustration of it, the tension being independent of its dimensions. Waves of displacement parallel to the surface of the film would not be transmitted. But such a film in consequence of its tension has an apparent rigidity for displacements normal to its surface; it can transmit transverse waves with a velocity which depends on the tension. Now the labile ether is a medium which has, in three dimensions, characteristics resembling those of the two dimensional film. Given such a medium—and there is nothing impossible in its conception—and the main phenomena of light follow as a necessary consequence. Lord Kelvin, again, has shown us how such a medium might be made up of molecules, having rotation in such a way that it could not be distinguished from an ordinary fluid in respect to any rotational motion; it would, however, resist rotational movements with a force proportional to the twist, just the force required. The medium has no real rigidity, but only a quasi rigidity conferred on it by its rotational motion. The actual periodic displacements of such a medium may constitute light. We may claim, then, with some confidence, to have a mechanical theory of light. But nowadays the ether has other functions to perform, and there is another theory to consider, which at present holds the field. Maxwell's equations of the electro-magnetic field are practically identical with those of the quasi-labile ether. The symbols which oocur can have an electromagnetic meaning; we speak of permeability and inductive capacity instead of rigidity and density, and take as our variables the electric or magnetic displacements instead of the actual displacement of the rotation. Still, such a thing is not mechanical, and we have no satisfactory mechanical theory of the electro-magnetic field. But the theory of the quasi-labile ether may be applied, and gives two analogies according as we regard the density of the medium to be analogous to electrostatic inductive capacity or to magnetic permeability.


Explorations in Thibet.—In a paper on Recent Explorations in Thibet, Mr. E. Delmar Morgan said in the British Association that the discoveries made by travelers, beginning with the Schlagintweit brothers and ending with Dr. Thorold's recent journey, had opened out new fields of research in hitherto inaccessible parts. They had determined the continuity of the Kuen Luen mountain system through twenty degrees of longitude, and made known the direction and structure of the principal chains. They had shown the lacustrine character of the central plateaus, and traced almost to their sources some of the mightiest rivers of Asia. They had thrown light on the climatic conditions of these lofty deserts, and seen an abundance of animal life on them. Their researches had proved the existence, in former times, of a line of flourishing oases along the northern foot of the Kuen Luen, by which the Chinese silk trade passed in the middle ages, and had brought to light the leading gold fields of northern Thibet.


Weather and the Mind.—The psychology of the weather is suggested by Dr. T. D. Crothers as a promising subject for study. He says, in Science: "Very few persons recognize the sources of error that come directly from atmospheric conditions on experimenters and observers and others. In my own case I have been amazed at the faulty deductions and misconceptions which were made in damp, foggy weather, or on days in which the air was charged with electricity and thunderstorms were impending. What seemed clear to me at these times appeared later to be filled with error. An actuary in a large insurance company is obliged to stop work at such times, finding that he makes so many mistakes which he is only conscious of later that his work is useless. In a large factory from ten to twenty per cent less work is brought out on damp days and days of threatening storm. The superintendent, in receiving orders to be delivered at a certain time, takes this factor into calculation. There is a theory among many persons in the fire-insurance business that in states of depressing atmosphere greater carelessness exists and more fires follow. Engineers of railway locomotives have some curious theories of trouble, accidents, and increased dangers in such periods, attributing them to the machinery." Dr. Crothers adds that the conviction prevails among many active brain workers in his circle that some very powerful forces coming from what is popularly called the weather control the work and its success of each one.


Seeking Perfection.—The Rev. J. A. Wylie, describing his journey through central Manchuria, speaks of a charming place, the Lao Te Ling, near Ta Shin Ho, where, at the summit of a hill, "there are several fine temples, including one, a large Buddhist temple, in course of erection; and in connection with this there is an interesting story. In a little house with eight leet by six feet of accommodation, two thirds of which is occupied by a small Kang, there lives a Buddhist priest. His head is not close-shaven, as the heads of other Buddhist priests are, for since taking up his residence in these quarters, or rather in this sentry box, he has allowed his locks to grow. For four years has he already been here, and another three years at least remain for him to stay. He is seeking to attain perfection, and he must finish what he has begun. Not until the temple is finished building will he be at liberty to leave his post. The little door of this priest's domicile is sealed up, so he never even steps out into the open air; there is only a small opening in the door or window for an attendant to hand in his meals. These meals are scanty and few; only one meal a day at noon. He drinks great quantities of tea, however; he seems to put no limit to his indulgence in that beverage. In sleep he does not stretch himself out; in fact, he never lies down, he only half reclines, and, asleep or awake, he constantly keeps pulling away at a rope which connects with the temple bell, which must never cease to ring. Travelers passing at all hours may hear the bell sounding; this is part of his work of merit. While I was with him, even although we spoke in such a way that everything else might be forgotten, he did not forget to pull the rope. How, during sleep, he manages is to me the mystery. He had heard long ago of the Christian religion; some books I offered him he refused, on the ground that before he had purified himself by completing his task it would be sacrilege to touch these books. When I pressed him he accepted them, however. How earnest must this man be when he thus denies himself! Still it is merit, and merit for himself, that he is endeavoring to attain."


Coal-dust Explosions.—A strong confirmation of the theory that coal dust is a frequent cause of explosions in coal mines is given by the experiments made in the White Moss Colliery, Skelmersdale, and recorded by Mr. Henry Hall, inspector of mines. It appears from them that the flame from a blowing-out gunpowder shot in the presence of dry coal dust is always found to ignite more or less such dust and to increase the burning and charring effects of the shot. When a large flame, such as that of a blowing-out gunpowder shot, or the flame from the ignition of a small quantity of fire damp. traverses an atmosphere containing a very moderate quantity of dry coal dust, the dusty atmosphere will explode with great violence, and the explosion will continue and pass throughout any length of such atmosphere, its violence and force increasing as it progresses. The coal dust from several seams in certain different districts is almost as sensitive to explosion as gunpowder itself, the degree of sensitiveness increasing in proportion to its high quality and freedom from impurities. In mines which are briskly ventilated there is a greater probability of explosion, while in such cases it is generally more severe. One of the most important results of the experiments made has been to demonstrate that certain high "explosives" (roburite, ammonite, etc.) are incapable of igniting or exploding coal dust. Mr. Hall, in face of these facts, is therefore led to urge the total abolition of gunpowder from coal mines for blasting purposes and the substitution of certain "high explosives"—precautionary measures which many large firms have already adopted. Apart from the danger of using gunpowder arising from the ease with which it starts a dust explosion, it appears that in mere handling alone four hundred lives have been sacrificed during the last twenty years, while the loss of life from explosions caused by gunpowder during the same time has been at least one half of the total loss—viz., 4,098 persons. With regard to preventive measures, every possible effort, it is recommended, should be made, either by watering the dry dust or removing it to avoid accumulation, so that any accidental ignition of fire damp may be limited in its effects and prevented from developing into a sweeping explosion through the agency of dust.


Birds of Michigan.—The Bird Fauna of Michigan, as described by Mr. A. J. Cook in a bulletin of the State Agricultural Experiment Station, being protected by the Great Lakes nearly surrounding the State, is very interesting. As is shown by Dr. C. Hart Merriam's colored map, it embraces representatives of three distinct faunas—viz., the boreal in the north, which includes the northern peninsula and the northern part of the southern peninsula; the transition, which occupies nearly all the southern peninsula, and reaches slightly into Indiana and Ohio; and the upper Sonoran, which, though mostly to the south of Michigan, reaches into the southeastern and southwestern corners of the State. There are met in Michigan many birds peculiar to the far north, and others that dwell for the most part in the States and countries to the south, even reaching to and beyond the Gulf. The first are illustrated in the Bohemian waxwing, the spruce partridge, the Canada jay, and the pine grosbeak; and the summer redbird, the mocking bird, and the cardinal redbird illustrate the second group. The large lakes attract many birds that are usually maritime, like the gulls and the terns; while in southern Michigan, with its prairies and woodlands, both widely distributed, are found the prairie fauna, as illustrated in the pinnated grouse, and those birds which are most at home in the forests of wooded areas, like most of the thrushes and the warblers.


The Future Work of the American University.—Addressing the Pennsylvania State Board of Agriculture on the Progress and Practical Value of Agricultural Science, Dr. Peter Collier gave a prominent place in illustration to the work that has been done in the analysis of fertilizers, whereby frauds have been exposed, and farmers have been pecuniarily benefited by the cheapening of fertilizing materials and the assurance of increased and improved crops. A further illustration is found in the progress and practical applications of bacteriology a word which, together with bacteria, does not occur in the standard dictionaries of 1868 by means of which the causes and cures of the most serious maladies that affect crops have been discovered and brought within the reach of all, and such operations as the making of butter and cheese are facilitated. One would not have imagined a short time ago that physics and physiology were the sisters of psychology, or that ethics should consort with economics and sociology in the same laboratory, or that a professor of institutional history should commend to his pupils biology as a minor subject. Yet all these things have really happened. Indeed, only since Darwin and Spencer has it been possible to discover the essential kinship of the various branches of knowledge. Projecting the future of the American university, the author assumes that it must become the representative of dynamic culture. The university should have much to do with social reforms, political regeneration, and correction of errors in the treatment of criminals. Social and political reform will be impossible without moral regeneration, in which, as the work must begin with the individual, the university has a noble part to perform. "The fact is, the American people need a tonic of the most active kind. Partly as a result of the spoils system and partly in consequence of the unnatural industrial and political conditions produced by the civil war, we have been brought to a very low plane of public morality. 'It is a familiar fact,' says Herbert Spencer, 'that the corporate conscience is ever inferior to the individual conscience.' Indeed, it seems to me that a nation is in evil straits when the standard of public morality is very much lower than the standard of private morality, and that is precisely the case with the people of the United States. Never, perhaps, has there been a greater disparity between political and private ethics. A double system of morality is a dangerous possession for any nation. Our ideal of public conduct must approximate more nearly to our ideal of private conduct if we would ever attain the best in the higher life."


Remaking our Boys.—"Boys, as they are made," as contemplated by F. H. Briggs, of the State Industrial School, Rochester, in an address concerning them, are not the boys who have home privileges and careful, competent home training, but the boys of the slums, and of the poor and the degraded. The question, How to remake them? is one that the public school should have an important part in answering. For the childboy, in the author's view, the kindergarten should be substituted for the home and street during the day, and one should be established, where all will be treated with equal consideration, in every locality where the poor abound. "The kindergarten gives the child the mental, physical, and moral exercise that it needs. . . . But what about the boys who are beyond the kindergarten age now, and about the boys who have passed through the kindergartens? Put them into manual training schools. . . . What should be the instruction in these schools? That which in a natural way develops the physical, mental, and moral faculties. The workshop should form an inseparable concomitant of every school. Children delight in doing. This is why the kindergarten is so effective as an educational agent." Our school for the boy should have drawing for its corner stone; and modeling should accompany it, that by the test of actual contact the correctness of the perceptions of size and form may be tested, and the love of the beautiful more fully gratified. Then the use of woodworking tools—the one thing that a boy always delights in. "It helps a boy to find out what square means. When he can saw to the line every time, he has a greater respect for truth. When he habitually becomes exact in the use of tools the great battle is won. Your skilled mechanic is not usually a liar. His respect for exactness makes him hard to the line in his speech. These three, then, drawing, modeling, and woodworking in its various forms, should form the foundation upon which our remaking structure should rest." And they should add development and symmetry to the whole. "These things lie at the very basis of all handicraft. They enable one trained in them to see things in new ways; to see their parts, their forms, their beauties; in fact, as training for the perceptive and conceptive faculties they have no equal. No scheme of education is complete that leaves music out." Nature has a warm place in every child's heart. It is ever presenting some new form for contemplation; "and as bud, leaf, flower, and fruit appear they challenge the child's attention and invite study. . . . Why has Nature been so long a closed book to the masses? Why is so much that is beautiful and ennobling denied to the famishing souls of little children? Why should natural history and science wait for the high-school or college course that the great mass of people never reach?"


Town Refuse as Fuel.—Experiments in seeking to utilize the refuse of towns as fuel have been carried so far that a plant, known as the Livèt plant, has been set up in Halifax, England, with which it is intended to supply electric energy. The successful working of the Livèt furnace appears to depend upon the peculiar construction of its flues, which are so built as to utilize the effect of the decreasing volume of the gases of combustion traveling toward the chimney, so promoting a high velocity to the air passing through the furnace bars and producing rapid combustion with intense heat. At the same time, the effect of this peculiarity of construction is to cause the gases themselves to move slowly through the flues, so that they may part with their useful heat before escaping into the atmosphere. The force of draught at the furnace is such that a high and constant temperature is obtained and efficiency of combustion insured, while all unpleasant odors inherent in town garbage are destroyed. As an example of the heat economy effected, it is said that whereas in previous, generators the best results ever obtained have been three quarters of a pound of water evaporated on the combustion of one pound of refuse, in the Livèt generator over three pounds of water are evaporated into steam for every pound of refuse consumed, in spite of the fact that it is frequently known to contain twenty per cent of moisture. The temperature of the gases just before entering the chimney is stated to be from 300º to 400º Fahr. lower than hitherto obtained. The progression of the gases is partially arrested at both ends of each flue for the purpose of permitting them to deposit the contained light dust in suitable expansion chambers or pits which can be cleaned out when desirable. This arrangement serves to overcome the objectionable dust, which in ordinary "destructors" tends to choke the flues and impregnate the ah-of the surrounding districts.


Uses of Drinks.—In discussing the question whether Australia will become a wine-drinking country. Dr. Murray Gibbs pointed out that different nations had always, from time immemorial, selected certain beverages as national drinks, and that the fact that the fruit, leaf, or grain supplying the essential principle of the drink was not always indigenous to the national soil was itself a proof that convenience was not the only factor indicating the choice. Many continental nations drink, of course, the wine of their particular district, and for centuries the Englishman's beer was made from the Englishman's barley. On the other hand, the universal vogue of drinking decoctions made from the Eastern shrubs tea and coffee shows that the popularity of a beverage has no geographical limits. The character of the drink adopted as national must always be largely dictated by the character of the soil and food, and this, in turn, is dependent upon the climate of the country. Sir William Roberts has said that all beverages, alcoholic or non-alcoholic, conduce to one of two conditions—retardation of the digestive process or excitation of the nervous system. The harsher climates require the stronger foods, and these—inasmuch as time is necessary for their proper assimilation—call for checks upon a too rapid and so incomplete digestion. Chief among these are the vegetable acids contained in wine, and the sedative properties of tea and coffee.


Occupations to awaken Dormant Faculties.—In a paper on Industrial Training in Reformatory Institutions (published by C. W. Bardeen, Syracuse, N. Y.) Mr. F. M. Briggs, of the State Industrial School, relates a few incidents of cases in which mental powers, before dormant, were awakened by setting pupils at work for which they had a taste. "There are boys in the State Industrial School at the present time," the author says, "whose interest we could not arouse in the common schools. Some were naturally so weak mentally that after weeks of conscientious work on the part of the teacher, they were not able to repeat from memory a four-verse stanza of a poem for children. Others would not apply themselves sufficiently long to learn anything. Some of these boys were placed in the clay-modeling and wood-carving shop. The boys who had been regarded as almost idiots soon began to show improvement. The boys who had been especially troublesome elsewhere, in the clay work ceased to be annoying. When a boy begins work with clay, he seems to feel himself in the unity of things and he becomes happy accordingly; and, as he sees the formless clay take shape beneath his touch, a sense of power is born within him which arouses and quickens him." A boy who had been cruel, cunning, and vicious, presenting no point for reaching his nature, one day in the wood-working shop asked his teacher to look at a molding board he had made. "The old spirit seemed to be gone as he showed me the result of his handiwork; unconsciously he had found the secret of power." Another boy, regarded as hardly more than an idiot, had been gaining in his shop work, with his eye taking new brightness and his face clearing; and his school work showed the effect of the shop training. Another boy, a persistent offender in shop and school, expressed a desire, when decorating was introduced, to do work of that kind. The request was granted, and "his first effort showed his ability, and a new manhood asserted itself within him."


Beginnings of Mountain Climbing.—The glaciers of the Alps began to attract the attention of scientific men toward the end of the seventeenth century, but travelers making the grand tour considered mountains hideous. It was not, says Mr. W. M. Conway, till the dawn of romanticism, a hundred years later, that the beauty of mountains began to be recognized. The first snow mountains to be climbed were the Titlis in 1739. Pococke and Windham's visit to the Chamounix followed in 1741, and with that the modern epoch of Alpine exploration may be said to have begun. In 1775 an attempt was made to reach the summit of Mont Blanc. This was repeated in several subsequent years, till in 1786 Jacques Balmat and Michel Paccard were successful. De Saussure's famous ascent was made in 1787. During the next half century the prejudice against mountains and dread of them were gradually dissolved. The Jungfrau was climbed in 1811, the Finsteraarhorn in 1812, and other peaks followed. It was not till after 1850 that systematic Alpine climbing could be said to have been introduced. The present Mr. Justice Willis's ascent of the Wetterhorn in 1854 was usually recognized as the first important "sporting" climb. Prom that time forward the exploration of the Alps advanced rapidly. Monte Rosa was climbed in 1855, Mont Blanc without guides and by a new road in 1856. In 1859 the Alpine Club was founded in London, and the example thus set was shortly afterward followed by foreign mountaineers. Thenceforward the exploration of the Alps advanced rapidly, and it might now be regarded as fairly complete, so far as the main groups are concerned.