Significant Books of Science

THE progress of knowledge appears immediately only in special papers, brief for the most part, highly technical, hardly readable except by the professional investigator. The amateur of learning, like another Lady of Shalott, sees but in a glass more or less darkly. Now the books which to the general reader mirror the gains of science fall rather naturally into three classes. There is, to begin with, the great negligible mass of works whose authors are more familiar with the typewriter than with the instruments of scientific research. Not infrequently, however, it happens that some special occasion, the leisure of old age, a worthy desire to turn an honest penny, induces some man of science to climb down from his high tower and converse on level terms with the man in the street. Once in a while, often apparently by sheer accident, a new contribution to science comes in readable form. Books of the first sort give one some idea of the outward fact; only those of the second, and especially of the third, reveal the inner spirit of science, its efficiency and its patience.

I

In certain ways the most remarkable book ever written is Euclid’s Geometry. Older texts are known to scholars, a few books as ancient are read by the multitude; what other work after twenty-two hundred years is still one of the best of school text-books and among the first authorities in its field ? Moreover, for every schoolboy of a larger growth, the country which he entered by way of the Asses’ Bridge remains his home as no other portion of the realm of knowledge ever does. Even though he remember the parallelopiped only as a dragon of the prime, he will, until he die, continue to think in terms of that Euclidian space into which he thinks he was born; while the higher criticism of Euclid’s axioms will always have a flavor of impiety.

Now for the first time in English, the writer of an elementary work attempts to go behind the intuitions which Euclid mistook for self-evident truths, and to introduce the race of schoolboys to a geometry based on pure reason. To be sure, when it comes to the parting of the ways, Professor Halsted’s pupils are to follow Euclid in assuming that through a given point there is only one parallel to a given line, and are to accept the conventional opinion concerning the sum of the angles of a triangle. Unlike Euclid, however, they will do these things with their eyes open, recognizing their choice as a convenient assumption among a group of possibilities equally reasonable and equally in accord with their daily experience. No longer, if the Non-Euclidians have their way, is the human mind to be fettered to the superstition that space is continuous, or that a line rotated about one of its points still retains its original length. Thus is the innate idea hunted from its last refuge. Thus is self-evident truth crushed permanently to earth.

II

Three books, hardly older in decades than Euclid in millenniums, have lately appeared in translation from new German editions. Wundt’s Physiological Psychology, Haeckel’s Evolution of Man, Suess’s Face of the Earth, are too well known to require comment; too important to be passed over in silence. Each is commonly thought to be the first authority in its field: together they set forth pretty completely all that is known thus far of “the bodily substrate of the mental life’’ of man, of the origin and history of the body itself, and of the outward aspect of the world on which it wanders up and down.

Haeckel, in addition to the translation of the Anthropogenie, has also a new book this year — but in quite his old manner. As always, he is prodigious of learning, fertile alike in illuminating suggestion and extraordinary new words; and as always, totally at sea as to what may reasonably be said in a popular book. There are, in fact, two Haeckels, as there are two Kants and two Tartarins. Haeckel Sancho Panza, the “practical” Haeckel, is one of the great, lights of nineteenth century science; Haeckel Quixote, the “pure” Haeckel, is the victim of a strange obsession concerning Monism and a violent antipathy toward persons in black coats. Haeckel I is a master of detailed evidence: for Haeckel II the eternal mystery of the relation of the soul to the nervous system becomes somehow plain if only each material atom be supposed to have a little soul of its own, — as if one hundred cents were fundamentally a different thing from one dollar. How the same man who wrote the Anthropogenie comes to write sentences like the following is one of those things which only the Society for Psychical Research can find out. “We find in crystallization, as in every chemical process, certain movements which are unintelligible without sensation —unconscious sensation, of course.” “We are bound to assume that there is a low degree of sensation (not of consciousness) in order to explain the orderly arrangement of the moving molecules in a definite structure.” “I am convinced that sensation is, like movement, found in all matter, and that this trinity of substance provides the safest basis for modern Monism.” What this means, I, at least, have but the haziest idea. Apparently it is intended to be “Monism:” obviously it is not Science.

The part which Haeckel took in the great controversy over the evolution of man was pretty accurately duplicated some two decades later by Weismann, in the debate over that extreme selectionism which, lucus a non lucendo, the world has taken to calling Darwinism. “When,” writes Weismann, “a life of pleasant labor is drawing to a close, the wish naturally asserts itself to gather together the main results, and to combine them in a well defined and harmonious picture which may be left as a legacy to succeeding generations.” From this worthy ambition have come Haeckel’s three volumes and Weismann’s Evolution Theory.

It is no slight evidence of the strength of his fundamental position that Weismann, who in absence of pride of opinion is hardly inferior to Darwin himself, after twenty years of battering, still stands to his guns. The course of a well-knit argument carries the reader along pleasant by-ways of insect coloration, protective mimicry, carnivorous plants, the marvels of animal instinct, and the strange lore of heredity which is the author’s especial field. Sooner or later, however, everything comes back to the set of opinions which Weismann has most completely elaborated and of which he has long been the foremost exponent. Not The, but My, Evolution Theory should have been Weismann’s title.

Weismann expressly declines to commit himself to the current doctrine that organic evolution must of necessity be so exceedingly slow a process that no appreciable advance can occur within the limits of one human lifetime. Nor was this Darwin’s opinion. Darwin, to be sure, took as a sort of motto, Natura non facit saltum ; but for all that, he saw that Nature, if she does not skip and jump, may on occasion take very unladylike strides. He knew among other things that peach trees occasionally bear nectarines, and the common rose-bush moss roses, and he knew that wheat, though cultivated from time out of mind, still continues to produce new varieties. In short, he recognized the possibility that within somewhat narrow limits the transmutation of species might take place suddenly. He did not, however, follow out this idea, but confined his attention to evolution by the slow accumulation of minute differences, believing this to be the more common type.

It has been the special work of Hugo de Vries of the University of Amsterdam to develop the side of the Darwinian theory which Darwin himself touched but lightly. De Vries, nevertheless, was by no means the first man to enter this field. Some ten years ago, Bateson, a zoölogist, brought out a bulky volume of observations on the discontinuity of inheritance among animals, — cases of extra digits, teeth, ribs, and limbs; of bull-dog faced cattle; of hairy birds; of “ angora ” cats, rabbits, cavies, and mice;—dimorphic species of all sorts; in which individuals have differed from their nearest ancestors very much as certain animal groups differ from their nearest allies. From these, Bateson argued very naturally that organic evolution, far more than is commonly supposed, takes place by fits and starts. Therefore, Bateson suggests, it may fall to the lot of some man to see a new species come into the world. De Vries is this fortunate man.

The toad flax, the common “butter and eggs” of childhood, though normally bearing irregular blossoms, has a variety the flowers of which are always regular. This regular form, first observed by a pupil of the great Linnæus, has been found growing wild in several different places, some of them so well known to collectors and so isolated from one another, that the plant must have originated somewhat suddenly and independently in more than one locality. Moreover, plants of the common type are known occasionally to produce one or two regular blossoms. In 1886, de Vries, chancing upon a plant of this sort, transferred it to his garden with the hope that, the change to Linaria vulgaris peloria might take place under his eyes. Eight years of vain waiting gave him no more than sporadic regular blossoms; and, thinking the experiment doomed to failure, he destroyed all his plants except two, one of which had borne the single regular flower of that year. During the next season the two plants bloomed freely, but produced only the common labiate flowers and about a teaspoonful of seed. A portion of this seed gave rise to some fifty plants, and of these one produced regular flowers only. Here, then, for the first time in the history of evolutionary studies, a new form appeared spontaneously under experimental conditions, from a known parentage and under the eye of a competent naturalist. In spite of all theory, the new plant did as a matter of fact come per saltum. Its ancestry was known during four generations; its immediate parents had borne, during two seasons, only one regular blossom out of thousands. Yet the variant produced nothing else, and never exhibited the slightest tendency to revert toward its forbears. The break of continuity occurred once, and once for all.

Later work has, of course, carried de Vries far beyond his first success. He has found several cases like the toad flax, and, in the still more remarkable instance of the mutations of Lamarck’s primrose, he has seen the origin of a really new species by one clean jump. The plant which had only Oenotheria Lamarckiana for its ancestors has only Oenotheria gigas for its descendants. Somewhere between one generation and the next the change occurs complete and final: there are no “links.” Moreover, de Vries has shown, by a wonderfully keen analysis of facts long known to every amateur botanist and gardener, how the essential phenomena of transmutation have been masked by their accessories; and has thus, for the first time, given a satisfactory account of the theory which underlies the rule-ofthumb devices of the practical breeder of domesticated animals and plants.

Species and Varieties, then, within the field of natural science, is clearly the book of the year. On the practical side it gives unity and significance to the random observations of every lover of plants; and makes clear how Mr. Luther Burbank, by applying on a characteristically Western scale the essential principles which have come down from pre-Darwinian times, has accomplished his marvelous results. On the theoretical side, the work articulates with Mendel’s old doctrine of the unit character, the heredity atom which either is or is not, and never splits in passing from one generation to the next: while the facts which it sets forth appear to have their most obvious interpretation in Weismann’s speculations concerning the mechanism of inheritance. Moreover, these strange breaks of continuity between parent and offspring, the sports of Darwin, the discontinuous variations of Bateson, the mutations of de Vries, have in them a curious flavor of the old-time doctrine of special creation. So far as this opinion admitted any precise statement, it connoted, apparently, phenomena of the same order, if on a somewhat larger scale, as that presented by the mutations of the great evening primrose and the toad flax. Once more, therefore, appears the ancient principle that no opinion generally held by seriousminded and able men is ever wholly wrong.

III

Physics, oldest of the natural sciences, so far from having settled down into respectable middle age, its field accurately delimited, its fundamental doctrines established once for all, has of late years, by its startling discoveries, quite put to shame the youngest of its grandchildren. Curiously, too, this revolution of opinion, probably the most rapid in the entire history of science, though it has extended into regions very remote from common interests, is involved in no small degree in so commonplace a matter as the interpretation of what really happens when the cook salts the broth. For the great contribution of the new science of physical chemistry, even now hardly more than half way toward its majority, has been the theory of solutions. On one side this theory has run off into the doctrine of solid solutions, which for the first time makes possible a really scientific metallurgy and gives us at last some profitable insight into the differences among cast iron, wrought iron, and steel. On the other hand, while we now know that one solid may be truly dissolved in another, we know also that, a solid, dissolved in a liquid, is essentially a gas; and that the osmotic pressure of a solution is ultimately the same thing as the expansive force of a confined vapor. Since, however, all the fluids of the living body are dilute solutions, the study of osmosis has done quite as much as any other one thing to make possible modern plant and animal physiology. To-day we know that osmotic pressure controls growth, and that even the artificial development of unfertilized eggs depends upon varying to just the right degree the osmotic tension within them.

Salted water, moreover, offers yet another set of problems. Sodium chloride in solution not only behaves like a gas, it also dissociates into free sodium and free chlorine. With the doctrine of ions comes at last an explanation of the cleansing power of soap anti of the action on the body of poisons and drugs. All this leads naturally to the ionization of gases and to the interpretation of the mysterious “fourth state of matter,” which is neither solid, liquid, nor gas. This in turn, most inappropriately, comes back to earth with a contribution to the theory of fogs. Nor is even this by any means the whole story.

The free ions of sodium and chlorine carry also their electric charges. In this lies the theory of electric batteries and the general behavior of electrolytes. But the negative charge of the chlorine ion, freed from its atomic bonds, appears as the cathode ray and also as one of the emanations of radium. With this goes inevitably the X-ray and the rest of the alphabetical forms of energy, which, in their turn, are more or less tied up with wireless telegraphy, the electro-magnetic theory of light, and the constitution of matter and of the ether itself. Not even the flower in the crannied wall can outdo a handful of table salt in revealing the nature of things.

The history of the astonishing discoveries of the last half dozen years has been set forth in a multitude of works which it were folly to enumerate. Many of them are excellent specimens of popular exposition in a difficult field; many, alas, are mere catalogues of signs and wonders hardly less confusing for an occasional lapse into accuracy. Beside these, however, there are some half dozen books which deserve special mention. All of them are by men who have made important contributions to knowledge in their special fields; all of them are untechnical without being fatuously popular; all of them, finally, are devoted less to expounding particular discoveries than to setting forth the relations and the real significance of the facts which most of us are supposed to have learned through the newspapers and magazines.

As an aid to orienting oneself in a field as obscure as it is interesting, I commend especially a little book by Professor Righi of the University of Bologna. One number of the Atlantic would contain it three times over; it presupposes on the part of the reader no more than a schoolboy’s knowledge; but it brings together into one coherent view all the fundamental ideas of the newer parts of physics, from the ionization of salted broth to the nature of electrons and the ultimate constitution of matter. Van’t Hoff of Berlin, equally brief but not quite equally simple, keeps well to the chemical side of the field. He is concerned for the most part with the theory of solutions, its application to solid solution, and the physical chemistry of living organisms. Loeb of California takes up the last of these topics from the physiological side. His studies include the action of ionized salts on living tissue, especially their influence upon growth and the regeneration of lost parts. In his two volumes are included all the more important of the original papers in which he announced the successive steps of his famous investigation into the development of unfertilized eggs. The experiments here discussed include the set in which he nursed his little fatherless sea-urchins safely through their larval stages. Far away on the other side of the field, Michelson of Chicago takes up the nature of ordinary light, with special attention to his own fruitful work with the latest tool of science, the interferometer, while Blondlot, by assembling the original papers in which he announced his discovery of the somewhat problematical “N” rays, affords a model of straightforward exposition.

Least in bulk of the books of this group, simplest in form, most radical in opinion, is an essay by a father in the scientific Israel. Mendeléeff’s “Periodic Table of the Chemical Elements” and the smell of hydrogen sulphide are the two items of school chemistry which are apt to linger longest in the adult mind. Mendeléeff’s Periodic Law, with its hints at the compound nature of the atom and the transmutation of metals, used to give the one suggestion of romance to the student whose interest lay in other fields. Of the newly discovered elements, radium dropped at once into the place which has been waiting for it a third of a century, and there is no reason for supposing that any other of the new metals will prove less tractable. The inert gases of the atmosphere, on the other hand, have shown no lack of energy in resisting all attempts to bring them into the periodic fold. The veteran Russian now essays to round out the great achievement of his life by corraling argon, helium, neon, krypton, xenon, the hypothetical coronium, and even the luminiferous ether itself. No bad way, this, to mark the completion of fifty years of scientific work.

IV

It now seems reasonably clear, in the light of recent work in Comparative Psychology, that there is but slender basis for the common assumption that conduct is either reasoned or instinctive. Far down below the level of true instincts lies the region of “tropisms.” The plant sends its roots toward water and its stem toward light, the blossom closes at eve,

by virtue of impulses which, in any proper sense, are no more “instinctive” than the behavior of iron filings in the field of a magnet.

Inevitably the doctrine of tropisms has colored all our interpretation of animal acts. It is no longer the fashion to admire the courage and intelligence of the salmon when it finds its way from the sea to its own birthplace among the hills; since it appears that the alleged instinct is but the exaggeration in the gravid fish of the general tendency of most water creatures to head up stream, like boats at anchor. This general point of view is especially well set forth by Professor Loeb, whose brilliant work in the no-man’s-land which lies about equally within the spheres of influence of Physical Chemistry, Physiology, and Psychology has made him the most conspicuous American exponent of these almost Cartesian opinions.

But if there is a type of animal behavior too primitive to be called instinctive, there is also another type, neither instinctive nor rational, which, lying between the two, may simulate the appearance of either. In fact, no small part of our own human conduct, to put the matter bluntly, which we flatter ourselves is determined by reason, is in reality the outcome of a series of random trials from which we have selected for repetition those of which the outcome chanced to be to our minds. Most of us seldom reason about everyday matters. We try one thing. If it works, we try it again. If it does not work, we try something else. Rarely in either case do we reason, save perhaps by analogy, toward an unknown condition. Practically most human conduct is intelligent, but not especially rational.

The great problem of animal psychology is to determine how far beasts, birds, and creeping things are only complex vegetables, and how far they are simplified men. On this point Dr. Jennings (for whom the life of even the simplest creatures is not altogether a problem of physics) has fairly carried the war into Africa by showing, as the result of a series of experiments extending over some halfdozen years, that even among the minute Infusoria, where rigid tropisms have been thought to reign supreme, there is nevertheless behavior founded on trial and failure essentially of the infrarational human sort. Unfortunately, Dr. Jennings’s studies (though his account of them is straightforward and intelligible) lie in a field remote from popular interests. Fortunately, the same ultimate problem has been taken up in a group of animals which has always appealed to the amateur of natural history.

Wasps, Social and Solitary, on its face, differs from half a hundred other “nature books” only in being considerably better. Here is, in more than usual measure, the leisurely charm, the lively humor, the sense of summer afternoons and still leaves and holding down the ground with one’s back, which one expects to find in books of this sort. Here, also, is no lack of amusing gossip concerning the doings of very fascinating little creatures. Beyond all this, however, there is “a hidden wealth of thought and of austerity” which makes the book a worthy contribution to science and a monument of patient and skillful research in a difficult field.

The work of Mr. Peckham and his wife, done both in private and on the Wisconsin Biological Survey, has already given them a more than national reputation among professional naturalists. Possibly because two heads, not too much alike, are better than one, they have combined to an unusual degree the basal excellences of the field observer with the critical habit of mind and the ability to make their work count toward the solution of some definite general problem which mark the man of science. The almost unique value of their work lies in the fact that they have been able to do in the field, under natural conditions, what other Students have done only in the laboratory.

Their evidence, because of the “strategic position” of the insects, cuts both ways. On the one hand, the everyday behavior of these most intelligent of invertebrates is utterly irrational; the most important acts of their lives have clearly no sort of meaning for them. So much for the sentimental “nature student.” On the other hand, the insects as a group have been thought to be preëminently the bond servants of instinct, the last of wellequipped animals to do anything for themselves. Nevertheless, it transpires that there is no little individuality among wasps of the same species, and that when the inherited impulse fails to accomplish its purpose the creature may on occasion adapt its behavior to circumstances. So much for the believers in the all-sufficiency of instincts.

Of late years an increasing body of evidence has seemed to indicate that the behavior of the higher animals is, for the most part, neither instinctive, in the sense that it is fixed by inheritance once for all, irrespective of the animal’s personal experience, nor rational, in the sense that the animal has any power of analyzing its own experience and recombining its elements to fit any new condition. An unreasoning intelligence based on a group of somewhat fluid instincts seems to guide the actions of the creatures which we know best. The observations of the Peckhams support amply this opinion. Wasp conduct turns out to be of the same general type as that of Infusorians and Atlantic readers. But the wasps, more than most of their fellow creatures, have had their side of the problem discussed with singular clarity and charm.

One must, it seems, look upon the wasp as a creature which is at times essentially a Cartesian machine, and yet at times also in some dim fashion a free agent. Over and over again in the observations of Mr. and Mrs. Peckham one sees the momentary loosening of the bonds of instinct, the single intelligent act, ere the shades of the prison-house close in again and the nervous mechanism takes control once more. Professor Davenport’s study of revivals of religion shows the same phenomenon under another guise. A being habitually intelligent, and occasionally rational, may also on occasion relapse into the life of instinct. The psychologists, indeed, will have it that we men have more different instincts than any other creature, and that only the conflict of diverse impulses makes possible our rational choice. But let any one of the great basal instincts, fear or imitation, burst its bounds and work its way unchecked, and it holds savage and philosopher alike in a grip like that of a tropism. In revivals of religion, as in other times of stress, shipwreck or theatre fire or financial panic, the fountains of the great deep are broken up and the blind primitive instincts submerge for the time the marketplaces and temples of the City of Mansoul. Who of us, after all, has not known occasions when his own conduct has been rather that of a wasp than of a man! For Professor Davenport revival meeting and lynching party alike show human nature stripped of its civilized garb and left naked to its enemies.

One may, however, admit in general terms that the essential phenomena of revivals lie within the field of comparative psychology, without feeling that Professor Davenport has been especially successful in treating the resulting problems. Sociologists as a group are inclined to take too much to heart the admonition of Dr. McCosh to the psychologists, not to let their subject degenerate into a mere science; and our author, like not a few of his colleagues, while trying hard to be a man of science, still sighs for the fleshpots of a sentimental Egypt. Too often there is but a ha’penny worth of evidence to an intolerable deal of edification. The three prominent ideas of the book — that the great awakenings of religion in America have started in communities which previously had been badly frightened, that an old-time revival rests ultimately on instinctive terror and is therefore impossible in a well-ordered modern state, that converts are often in part hypnotized — are all generalizations important enough to warrant a more rigidly scientific treatment than Professor Davenport sees fit to give them. Logan, Simpson, and Todd counties in Kentucky were the centre of the great revival of 1800, “During the entire first half of the nineteenth century this region was the home of bloody feuds, and during the latter half of the same century it was the great centre of the lynching spirit in Kentucky. This is but a single piece of evidence, and we may have here simply a coincidence.” Shades of Darwin! What does an investigator in the least of the real sciences do when he strikes a promising “coincidence?”

In the absence of anything corresponding to a coming-out party, it becomes a question of private judgment whether Psychical Research (for want of a better name) is a branch of science or not. Certainly Lord Layleigh, Sir William Crooks, Oliver Lodge, William James, Langley, Wallace, Henry Sidgwick, Balfour Stewart, are highly respectable chaperons for any scientific debutante. Moreover, the young science (if it be one) has done at least one good piece of work: to it, largely, orthodox Psychology owes the doctrine of the Subliminal Consciousness. But for F. W. H. Myers and the Society for Psychical Research, the world would know even less than it does of the cellars and galleries, the measureless caverns and the sunless seas of our human nature which stretch underneath the tidy apartments in which the conscious soul keeps house.

No one can, I think, follow the work for the last dozen years of a group of men whose achievements in other fields are a warrant for their accuracy and their skepticism in this, without feeling that (all interpretations aside) one fact at least has been established. Certain persons are able somehow or other to tap stores of detailed information which are tight shut to other men. It takes a pretty skeptical man nowadays to believe in ghosts, and a somewhat credulous man to believe in “brain waves.” Between telepathy and Spiritism there is at present neither a third possibility nor any considerable basis for a reasonable choice. The Society for Psychical Research commits itself officially to neither.

A modest volume by a vice-president of the Society sums up with admirable clearness the case between the two possibilities. Professor Hyslop’s book stands related to the general mass of “borderland” phenomena just about as the group of books which I have already mentioned is related to the newer discoveries in physics and physical chemistry,— it is a popular digest of a considerable body of more technical works, in which, naturally, the results of the author’s own investigations appear with some fullness. It belongs therefore with a group of books, numerable on the fingers of one hand, which, treating of matters occult, articulate with a body of fact and doctrine in aspect at least scientific. Now science, like the common law, has adopted certain conventions with regard to admissible evidence. Doubtless because of them many a villain goes unhanged and many a sound opinion is accounted superstition. Doubtless, too, in the long run, these conventions do help to make truth and justice prevail. At any rate, there they are; and we are not supposed to hang manifest rascals nor accept obvious facts without conforming to them. That Professor Hyslop has taken the trouble to be formally scientific makes no small part of the value of his discussion. So far as it shall turn out that he is wrong, his mistakes are those of a just and competent judge, not those of one who lends money to a plausible stranger.

What, from any point of approach, is one to make of a fact like this ? Here is a woman’s hand, which, while its nominal owner is engaged in the give and take of question and answer (not, to be sure, quite in propria persona), maintains by means of pencil and paper its own independent conversation; replies coherently to remarks addressed to it; and in general behaves like a rational being, even when the left hand which goes with it is struggling undextrously to write out quite a different message! Moreover, it, or she, or he, claims to be a deceased member of the Society for Psychical Research, reminds one of its officers of a promise made in private to have a hand in the work of the society from the other side of the gulf; recognizes its alleged friends and belongings; exhibits (albeit with many unaccountable lapses) an intimate knowledge of its mundane affairs; goes to work systematically to prove its identity; offers valuable suggestion and advice concerning the conduct of the experiment; and in general comports itself as a member of the Psychical Society triumphant might naturally be expected to do. One’s dogmatic slumbers must indeed be deep if he does not feel the jolt of facts like these in whatever way he interprets them. No longer, however, may the sleeper lull himself again to dreamland with gentle murmurs of “fraud;” “a fraud which is no assigned kind of fraud, but simply ‘fraud’at large, fraud in abstracto, can hardly be regarded as a specifically scientific explanation of specific concrete facts.”

v

Highly characteristic of the scale of values of the latest and most, ambitious general history of science is the relative space allotted to some of the worthies whom I have mentioned. Van’t Hoff and Wundt get half a dozen lines apiece, Suess and de Vries do not appear at all. Mendeléeff gets a page, and Weismann something more. Haeckel gets thirty-odd pages, some four times the number given to Bacon, Leibnitz, and Descartes together! For the reason, doubtless, that there is at present no very clear call for a critical treatment of his subject, Dr. Williams has frankly addressed himself to the general reading public, and has produced a work as interesting as novels once had the reputation of being, and interesting in much the same way. Inevitably, the murmuring shallows of science are more in evidence than its silent deeps; its thaumaturgics than its revelations. All this is somewhat trying to the student. For the student, however, there is already no lack of adequate works in this field; he should be the last to begrudge to the general reader the one book which best meets his demands.

I began this review with a book in which our deepest-seated intuitions are so far reduced to mere conventions that, for all we really know, a straight line indefinitely prolonged may return on itself after passing round through the other side of nowhere. Another maintains, against the universal consensus of mankind, that all the evil which men do, and all the good, are alike interred with their bones, so far as any effect on the heritage of their sons is concerned; while the author of a third would not need to revise his fundamental ideas if he discovered a bramble bush bearing some sort of grapes. A fourth treats of a mysterious ether, the basis of pretty much all the phenomena of the physical world, a medium at the same time “far more solid than steel and far less viscous than the lightest known gas;” vet in spite of this, “the only form of matter about which we know anything at all.” For a fifth this same anomalous ether is merely a chemical element of the argon group. Finally, comes a book in which the dead speak with tongues. All but one of these opinions are respectable, orthodox science. Who, without being told, could guess which ?