A HISTORY OF SCIENCE

By Henry Smith Williams

Assisted By Edward H. Williams

In Five Volumes

VOLUME V.

Aspects Of Recent Science

New York And London

Harper And Brothers

Copyright, 1904, by Harper & Brothers.

Published November, 1904.



CONTENTS

BOOK V

CHAPTER I—THE BRITISH MUSEUM

The founding of the British Museum, p. 4—Purchase of Sir Hans Sloane's collection of curios by the English government, p. 4—Collection of curios and library located in Montague Mansion, p. 5—Acquisition of the collection of Sir William Hamilton, p. 5—Capture of Egyptian antiquities by the English, p. 5—Construction of the present museum building, p. 6—The Mesopotamian department, p. 8—The Museum of Natural History in South Kensington, p. 8—Novel features in the structure of the building, p. 9—Arrangement of specimens to illustrate evolution, protective coloring, etc., p.— —Exhibits of stuffed specimens amid their natural surroundings, p. 10—Interest taken by visitors in the institution, p. 12.

CHAPTER II—THE ROYAL SOCIETY OP LONDON FOR IMPROVING NATURAL KNOWLEDGE

The Royal Society, p. 14—Weekly meetings of the society, p. 15—The tea before the opening of the lecture, p. 15—Announcement of the beginning of the lecture by bringing in the great mace, p. 16—The lecture-room itself, p. 17—Comparison of the Royal Society and the Royal Academy of Sciences at Berlin, p. 18—The library and reading-room, p. 19—The busts of distinguished members, p. 20—Newton's telescope and Boyle's air-pump, p. 21.

CHAPTER III—THE ROYAL INSTITUTION AND LOW-TEMPERATURE RESEARCHES

The founding of the Royal Institution, p. 29—Count Rumford, p. 30—His plans for founding the Royal Institution, p. 32—Change in the spirit of the enterprise after Rumford's death, p. 33—Attitude of the earlier workers towards the question of heat as a form of motion, p. 34—Experiments upon gases by Davy and Faraday, p. 35—Faraday's experiments with low temperatures, p. 39—Other experiments to produce lower temperature, p. 39—Professor De-war begins low-temperature research, p. 39—His liquefaction of hydrogen, p. 43—Hampson's method of producing low temperatures, p. 44—Dewar's invention of the vacuum vessel, p. 53—Its use in retaining liquefied gases, p. 54—Changes in physical properties of substances at excessively low temperatures, p. 56—Magnetic phenomena at low temperatures, p. 56—Changes in the color of substances at low temperatures, p. 57—Substances made luminous by low temperatures, p. 58—Effect of low temperatures upon the strength of materials, p. 59—Decrease of chemical activity at low temperatures, p. 60—Olzewski's experiments with burning substances in liquid oxygen, p. 61—Approach to the absolute zero made by liquefying hydrogen, p. 69—Probable form of all matter at the absolute zero, p. 70—Uncertain factors that enter into this determination, p. 71.

CHAPTER IV—SOME PHYSICAL LABORATORIES AND PHYSICAL PROBLEMS

Sir Norman Lockyer and Spectroscopic Studies of the Sun and Stars, p. 73—Observations made at South Kensington by Sir Norman and his staff, p. 74—His theories as to the influence of sun-spots and terrestrial weather, p. 75—Spectroscopic studies of sun-spots, p. 76—Studies of the so-called reverse lines of the spectrum, p. 78—Discovery of the new star in the constellation of Perseus, p. 80—Spectroscopic studies of the new star, p. 81—Professor Ramsay and the new gases, p. 82—University College in London, p. 83—Professor Ramsay's laboratory and its equipment, p. 84—The discovery of argon, p. 86—Professor Ramsay's work on krypton, neon, and zenon, p. 87—Discoveries of new constituents of the atmosphere, p. 88—Interesting questions raised by these discoveries, p. 89—Professor J. J. Thomson and the nature of electricity, p. 92—Study of gases in relation to the conduction of electricity, p. 93—Electricity regarded as a form of matter, p. 97—Radio-activity, p. 97—The nature of emanations from radio-active bodies, p. 10a—The source of energy of radioactivity, p. 106—Radio-activity and the structure of the atom, p. 108—Effect of radio-activity upon heat-giving life of the sun and the earth, p. 111.

CHAPTER V—THE MARINE BIOLOGICAL LABORATORY

The aquarium, p. 113—The arrangement of the tanks and exhibits, p. 114—The submarine effect of this arrangement, p. 115—Appearance of the submarine dwellers in their natural surroundings, p. 116—The eels and cuttle-fishes, p. 116—The octopuses, p. 117—The technical department of the laboratory, p. 119—The work of Dr. Anton Dohrn, founder of the laboratory, p. 121—The associates of Dr. Dohrn, p. 122—The collecting of surface specimens, p. 123—Collecting specimens by dredging, p. 124—Fauna of the Bay of Naples, p. 124—Abundance of the material for biological study, p. 125—Advantages offered by marine specimens for biological study, p. 126—Method of preserving jelly-fish and similar fragile creatures, p. 127—Uses made of the specimens in scientific study, p. 128—Different nationalities represented among the workers at the laboratory, p. 130—Methods of investigation, p. 131—Dr. Diesch's studies of heredity at the laboratory, p. 131—Other subjects under scientific investigation, p. 132—The study of chromosomes, p. 133—Professor Weismann's theory of heredity based on these studies, p. 33—Experiments in the division of egg-cells, p. 134—Experiments tending to refute Weismann's theory, p. 136—Dr. Dohrn*s theory of the type of the invertebrate ancestor, p. 137—Publications of the laboratory, p. 139—Meetings of the investigators at Signor Bifulco's, p. 141—Marine laboratories of other countries, p. 142.

CHAPTER VI—ERNST HAECKEL AND THE NEW ZOOLOGY

The "dream city" of Jena, p. 145—The old market-place, p. 147—The old lecture-halls of the university, p. 148—Ernst Haeckel, p. 151—His discoveries of numerous species of radiolarians, p. 153—The part played in evolution by radiolarians, p. 156—Haeckel's work on morphology, and its aid to Darwinian philosophy, p. 156—Freedom of thought and expression in the University of Jena, p. 157—Haeckel's laboratory, p. 160—His method of working, p. 161—His methods of teaching, p. 164—The import of the study of zoology, p. 166—Its bearing upon evolution, p. 168—The present status of Haeckel's genealogical tree regarding the ancestry of man, p. 171—Dubois's discovery of the skull of the ape-man of Java, p. 173—Its close resemblance to the skull of the ape, p. 173—Man's line of descent clearly traced by Haeckel, p. 175—The "missing link" no longer missing, p. 176.

CHAPTER VII—SOME MEDICAL LABORATORIES AND MEDICAL PROBLEMS

The Boulevard Pasteur, p. 179—The Pasteur Institute, p. 180—The tomb of Pasteur within the walls, p. 181—Aims and objects of the Pasteur Institute, p. 182—Antirabic treatment given, p. 183—Methods of teaching in the institute, p. 185—The director of the institute and his associates, p. 185—The Virchow Institute of Pathology, p. 186—Studies of the causes of diseases, p. 187—Organic action and studies of cellular activities, p. 188—The discoveries of Rudolph Virchow, p. 188—His work in pathology, p. 189—Character of the man, his ways of living and working, p. 189—His methods of lecturing and teaching, p. 191—The Berlin Institute of Hygiene, p. 193—Work of Professor Koch as carried on in the institute, p. 194—Work of his successors in the institute, p. 195—Investigations in hygiene, p. 196—Investigations of the functions of the human body in their relations to everyday environment, p. 197—The Museum of Hygiene, p. 198—Studies in methods of constructing sewerage systems in large cities, p. 199—Studies in problems of ventilation, p. 200.

CHAPTER VIII—SOME UNSOLVED SCIENTIFIC PROBLEMS

The ever-shifting ground of scientific progress, p. 203—Solar and telluric problems, p. 205—Mayer's explanation of the continued heat of the sun, p. 206—Helmholtz's suggestion as to the explanation, p. 207—The estimate of the heat-giving life of the sun by Lord Kelvin and Professor Tait, p. 208—Lockyer's suggestion that the chemical combination of elements might account for the sun's heat, p. 209—Computations as to the age of the earth's crust, p. 210—Lord Kelvin's computation of the rigidity of the telluric structure, p. 211—Estimates of the future life of the earth, p. 212—Physical problems, p. 213—Attempts to explain the power of gravitation, p. 214—The theory of Le Sage, p. 214—Speculations based upon the hypothesis of the vortex atom, p. 216—Lord Kelvin's estimate of the vortex theory, p. 217—Attempted explanation of the affinity of atoms, p. 217—Solubility, as explained by Ostwald and Mendeleef, p. 218—Professor Van 't Hoof's studies of the space relations of atoms, p. 219—Life problems, p. 220—Question as to living forms on other worlds besides our own, p. 21 x—The question of the "spontaneous generation" of living protoplasm, p. 222—The question of the evolution from non-vital to vital matter, p. 223—The possibility of producing organic matter from inorganic in the laboratory, p. 224—Questions as to the structure of the cell, p. 225—Van Beneden's discovery of the centrosome, p. 226—Some problems of anthropology, p. 227.

CHAPTER IX—RETROSPECT AND PROSPECT

The scientific attitude of mind, p. 2 30—Natural versus supernatural, p. 233—Inductive versus deductive reasoning, p. 235—Logical induction versus hasty generalization, p. 239—The future of Darwinism, p. 241.

APPENDIX

A LIST OF SOURCES



A HISTORY OF SCIENCE—BOOK V



ASPECTS OF RECENT SCIENCE

STUDENTS of the classics will recall that the old Roman historians were accustomed to detail the events of the remote past in what they were pleased to call annals, and to elaborate contemporary events into so-called histories. Actuated perhaps by the same motives, though with no conscious thought of imitation, I have been led to conclude this history of the development of natural science with a few chapters somewhat different in scope and in manner from the ones that have gone before.

These chapters have to do largely with recent conditions. Now and again, to be sure, they hark back into the past, as when they tell of the origin of such institutions as the British Museum, the Royal Society, and the Royal Institution; or when the visitor in modern Jena imagines himself transplanted into the Jena of the sixteenth century. But these reminiscent moods are exceptional. Our chief concern is with strictly contemporary events—with the deeds and personalities of scientific investigators who are still in the full exercise of their varied powers. I had thought that such outlines of the methods of contemporary workers, such glimpses of the personalities of living celebrities, might form a fitting conclusion to this record of progress. There is a stimulus in contact with great men at first hand that is scarcely to be gained in like degree in any other way. So I have thought that those who have not been privileged to visit the great teachers in person might like to meet some of them at second hand. I can only hope that something of the enthusiasm which I have gained from contact with these men may make itself felt in the succeeding pages.

It will be observed that these studies of contemporary workers are supplemented with a chapter in which a hurried review is taken of the field of cosmical, of physical, and of biological science, with reference to a few of the problems that are still unsolved. As we have noted the clearing up of mystery after mystery in the past, it may be worth our while in conclusion thus to consider the hordes of mysteries which the investigators of our own age are passing on to their successors. For the unsolved problems of to-day beckon to the alluring fields of to-morrow.



I. THE BRITISH MUSEUM

IN the year 1753 a remarkable lottery drawing took place in London. It was authorized, through Parliament, by "his gracious Majesty" King George the Second. Such notables as the archbishop of Canterbury and the lord chancellor of the realm took official interest in its success. It was advertised far and wide—as advertising went in those days—in the Gazette, and it found a host of subscribers. Of the fifty thousand tickets—each costing three pounds—more than four thousand were to be of the class which the act of Parliament naively describes as "fortunate tickets." The prizes aggregated a hundred thousand pounds.

To be sure, state lotteries were no unique feature in the England of that day. They formed as common a method of raising revenue in the island realm of King George II. as they still do in the alleged continental portion of his realm, France, and in the land of his nativity, Germany. Indeed, the particular lottery in question was to be officered by the standing committee on lotteries, whose official business was to "secure two and a half million pounds for his Majesty" by this means. But the great lottery of 1754 had interest far beyond the common run, for it aimed to meet a national need of an anomalous kind—a purely intellectual need. The money which it was expected to bring was to be used to purchase some collections of curiosities and of books that had been offered the government, and to provide for their future care and disposal as a public trust for the benefit and use of the people. The lottery brought the desired money as a matter of course, for the "fool's tax" is the one form of revenue that is paid without stint and without grumbling. Almost fifty thousand pounds remained in the hands of the archbishop of Canterbury and his fellow-trustees after the prizes were paid. And with this sum the institution was founded which has been increasingly famous ever since as the British Museum.

The idea which had this splendid result had originated with Sir Hans Sloane, baronet, a highly respected practising physician of Chelsea, who had accumulated a great store of curios, and who desired to see the collection kept intact and made useful to the public after his death. Dying in 1753, this gentleman had directed in his will that the collection should be offered to the government for the sum of twenty thousand pounds; it had cost him fifty thousand pounds. The government promptly accepted the offer—as why should it not, since it had at hand so easy a means of raising the necessary money? It was determined to supplement the collection with a library of rare books, for which ten thousand pounds was to be paid to the Right Honorable Henrietta Cavendish Holies, Countess of Oxford and Countess Mortimer, Relict of Edward, Earl of Oxford and Earl Mortimer, and the Most Noble Margaret Cavendish, Duchess of Portland, their only daughter.

The purchases were made and joined with the Cottonian library, which was already in hand. A home was found for the joint collection, along with some minor ones, in Montague Mansion, on Great Russell Street, and the British Museum came into being. Viewed retrospectively, it seems a small affair; but it was a noble collection for its day; indeed, the Sloane collection of birds and mammals had been the finest private natural history collection in existence. But, oddly enough, the weak feature of the museum at first was exactly that feature which has been its strongest element in more recent years—namely, the department of antiquities. This department was augmented from time to time, notably by the acquisition of the treasures of Sir William Hamilton in 1773; but it was not till the beginning of the nineteenth century that the windfall came which laid the foundation for the future incomparable greatness of the museum as a repository of archaeological treasures.

In that memorable year the British defeated the French at Alexandria, and received as a part of the conqueror's spoils a collection of Egyptian antiquities which the savants of Napoleon's expedition had gathered and carefully packed, and even shipped preparatory to sending them to the Louvre. The feelings of these savants may readily be imagined when, through this sad prank of war, their invaluable treasures were envoyed, not to their beloved France, but to the land of their dearest enemies, there to be turned over to the trustees of the British Museum.

The museum authorities were not slow to appreciate the value of the treasures that had thus fallen into their hands, yet for the moment it proved to them something of a white elephant. Montague Mansion was already crowded; moreover, its floors had never been intended to hold such heavy objects, so it became imperatively necessary to provide new quarters for the collection. This was done in 1807 by the erection of a new building on the old site. But the trustees of that day failed to gauge properly the new impulse to growth that had come to the museum with the Egyptian antiquities, for the new building was neither in itself sufficient for the needs of the immediate future nor yet so planned as to be susceptible of enlargement with reasonable architectural effect. The mistakes were soon apparent, but, despite various tentatives and "meditatings," fourteen years elapsed before the present magnificent building was planned. The construction, wing by wing, began in 1823, but it was not until 1846 that the last vestige of the old museum buildings had vanished, and in their place, spreading clear across the spacious site, stood a structure really worthy of the splendid collection for which it was designed.

But no one who sees this building to-day would suspect its relative youth. Half a century of London air can rival a cycle of Greece or Italy in weathering effect, and the fine building of the British Museum frowns out at the beholder to-day as grimy and ancient-seeming as if its massive columns dated in fact from the old Grecian days which they recall. Regardless of age, however, it is one of the finest and most massive specimens of Ionic architecture in existence. Forty-four massive columns, in double tiers, form its frontal colonnade, jutting forward in a wing at either end. The flight of steps leading to the central entrance is in itself one hundred and twenty-five feet in extent; the front as a whole covers three hundred and seventy feet. Capping the portico is a sculptured tympanum by Sir Richard Westmacott, representing the "Progress of Civilization" not unworthily. As a whole, the building is one of the few in London that are worth visiting for an inspection of their exterior alone. It seems admirably designed to be, as it is, the repository of one of the finest collections of Oriental and classical antiquities in the world.

There is an air of repose about the ensemble that is in itself suggestive of the Orient; and the illusion is helped out by the pigeons that flock everywhere undisturbed about the approaches to the building, fluttering to be fed from the hand of some recognized friend, and scarcely evading the feet of the casual wayfarer. With this scene before him, if one will close his ears to the hum of the great city at his back he can readily imagine himself on classical soil, and, dreaming of Greece and Italy, he will enter the door quite prepared to find himself in the midst of antique marbles and the atmosphere of by-gone ages.

I have already pointed out that the turning-point in the history of the British Museum came just at the beginning of the century, with the acquisition of the Egyptian antiquities. With this the institution threw off its swaddling-clothes. Hitherto it had been largely a museum of natural history; in future, without neglecting this department, it was to become equally important as a museum of archaeology. The Elgin marbles, including the wonderful Parthenon frieze, confirmed this character, and it was given the final touch by the reception, about the middle of the century, of the magnificent Assyrian collection just exhumed at the seat of old Nineveh by Mr. (afterwards Sir Henry) Layard. Since then these collections, with additions of similar character, have formed by far the most important feature of the British Museum. But in the mean time archaeology has become a science.

Within recent years the natural history collection has been removed in toto from the old building to a new site far out in South Kensington, and the casual visitor is likely to think of it as a separate institution. The building which it occupies is very modern in appearance as in fact. It is a large and unquestionably striking structure, and one that gives opportunity for very radical difference of opinion as to its architectural beauty. By some it is much admired; by others it is almost equally scoffed at. Certain it is that it will hardly bear comparison with the parent building in Great Russell Street.

Interiorly, the building of the natural history museum is admirably adapted for its purpose. Its galleries are for the most part well lighted, and the main central hall is particularly well adapted for an exhibition of specimens, to which I shall refer more at length in a moment. For the rest there is no striking departure from the conventional. Perhaps it is not desired that there should be, since long experience seems to have settled fairly well the problem of greatest economy of space, combined with best lighting facilities, which always confronts the architect in founding a natural history museum.

There is, however, one striking novel feature in connection with the structure of the natural history museum at Kensington which must not be overlooked. This is the quite unprecedented use of terra-cotta ornamentation. Without there is a striking display of half-decorative and half-realistic forms; while within the walls and pillars everywhere are covered with terracotta bas-reliefs representing the various forms of life appropriate to the particular department of the museum which they ornament. This very excellent feature might well be copied elsewhere, and doubtless will be from time to time.

As to the exhibits proper within the museum, it may be stated in a word that they cover the entire range of the faunas and floras of the globe in a variety and abundance of specimens that are hardly excelled anywhere, and only duplicated by one or two other collections in Europe and two or three in America.

It would be but a reiteration of what the catalogues of all large collections exhibit were one to enumerate the various forms here shown, but there are two or three exhibits in this museum which are more novel and which deserve special mention. One of these is to be found in a set of cases in the main central hall. Here are exhibited, in a delightfully popular form, some of the lessons that the evolutionist has taught us during the last half-century. Appropriately enough, a fine marble statue of Darwin, whose work is the fountain-head of all these lessons, is placed on the stairway just beyond, as if to view with approval this beautiful exemplification of his work.

One of these cases illustrates the variations of animals under domestication, the particular specimens selected being chiefly the familiar pigeon, in its various forms, and the jungle-fowl with its multiform domesticated descendants.

Another case illustrates very strikingly the subject of protective coloration of animals. Two companion cases are shown, each occupied by specimens of the same species of birds and animals—in one case in their summer plumage and pelage and in the other clad in the garb of winter. The surroundings in the case have, of course, been carefully prepared to represent the true environments of the creatures at the appropriate seasons. The particular birds and animals exhibited are the willow-grouse, the weasel, and a large species of hare. All of these, in their summer garb, have a brown color, which harmonizes marvellously with their surroundings, while in winter they are pure white, to match the snow that for some months covers the ground in their habitat.

The other cases of this interesting exhibit show a large variety of birds and animals under conditions of somewhat abnormal variation, in the one case of albinism and the other of melanism. These cases are, for the casual visitor, perhaps the most striking of all, although, of course, they teach no such comprehensive lessons as the other exhibits just referred to.

The second of the novel exhibits of the museum to which I wish to refer is to be found in a series of alcoves close beside the central cases in the main hallway.

Each of these alcoves is devoted to a class of animals—one to mammals, one to birds, one to fishes, and so on. In each case very beautiful sets of specimens have been prepared, illustrating the anatomy and physiology of the group of animals in question. Here one may see, for example, in the alcove devoted to birds, specimens showing not only details of the skeleton and muscular system, but the more striking examples of variation of form of such members as the bill, legs, wings, and tails. Here are preparations also illustrating, very strikingly, the vocal apparatus of birds. Here, again, are finely prepared wings, in which the various sets of feathers have been outlined with different-colored pigments, so that the student can name them at a glance. In fact, every essential feature of the anatomy of the bird may be studied here as in no other collection that I know of. And the same is true of each of the other grand divisions of the animal kingdom. This exhibit alone gives an opportunity for the student of natural history that is invaluable. It is quite clear to any one who has seen it that every natural history museum must prepare a similar educational exhibit before it can claim to do full justice to its patrons.

A third feature that cannot be overlooked is shown in the numerous cases of stuffed birds, in which the specimens are exhibited, not merely by themselves on conventional perches, but amid natural surroundings, usually associated with their nests and eggs or young. These exhibits have high artistic value in addition to their striking scientific worth. They teach ornithology as it should be taught, giving such clews to the recognition of birds in the fields as are not at all to be found in ordinary collections of stuffed specimens. This feature of the museum has, to be sure, been imitated in the American Museum of Natural History in New York, but the South Kensington Museum was the first in the field and is still the leader.

A few words should be added as to the use made by the public of the treasures offered for their free inspection by the British Museum. I shall attempt nothing further than a few data regarding actual visits to the museum. In the year 1899 the total number of such visits aggregated 663,724; in 1900 the figures rise to 689,249—well towards three-quarters of a million. The number of visits is smallest in the winter months, but mounts rapidly in April and May; it recedes slightly for June and July, and then comes forward to full tide in August, during which month more than ninety-five thousand people visited the museum in 1901, the largest attendance in a single day being more than nine thousand. August, of course, is the month of tourists—particularly of tourists from America—but it is interesting and suggestive to note that it is not the tourist alone who visits the British Museum, for the flood-tide days of attendance are always the Bank holidays, including Christmas boxing-day and Easter Monday, when the working-people turn out en masse. On these days the number of visits sometimes mounts above ten thousand.

All this, it will be understood, refers exclusively to the main building of the museum on Great Russell Street. But, meantime, out in Kensington, at the natural history museum, more than half a million visits each year are also made. In the aggregate, then, about a million and a quarter of visits are paid to the British Museum yearly, and though the bulk of the visitors may be mere sight-seers, yet even these must carry away many ideas of value, and it hardly requires argument to show that, as a whole, the educational influence of the British Museum must be enormous. Of its more direct stimulus to scientific work through the trained experts connected with the institution I shall perhaps speak in another connection.



II. THE ROYAL SOCIETY OF LONDON FOR IMPROVING NATURAL KNOWLEDGE

A SESSION OF THE SOCIETY

THERE is one scientific institution in London more venerable and more famous even than the British Museum. This, of course, is the Royal Society, a world-famous body, whose charter dates from 1662, but whose actual sessions began at Gresham College some twenty years earlier. One can best gain a present-day idea of this famous institution by attending one of its weekly meetings in Burlington House, Piccadilly—a great, castle-like structure, which serves also as the abode of the Royal Chemical Society and the Royal Academy of Arts. The formality of an invitation from a fellow is required, but this is easily secured by any scientific visitor who may desire to attend the meeting. The programme of the meeting each week appears in that other great British institution, the Times, on Tuesdays.

The weekly meeting itself is held on Thursday afternoon at half-past four. As one enters the door leading off the great court of Burlington House a liveried attendant motions one to the rack where great-coat and hat may be left, and without further ceremony one steps into the reception-room unannounced. It is a middle-sized, almost square room, pillared and formal in itself, and almost without furniture, save for a long temporary table on one side, over which cups of tea are being handed out to the guests, who cluster there to receive it, and then scatter about the room to sip it at their leisure. We had come to hear a lecture and had expected to be ushered into an auditorium; but we had quite forgotten that this is the hour when all England takes its tea, the elite of the scientific world, seemingly, quite as much as the devotees of another kind of society. Indeed, had we come unawares into this room we should never have suspected that we had about us other than an ordinary group of cultured people gathered at a conventional "tea," except, indeed, that suspicion might be aroused by the great preponderance of men—there being only three or four women present—and by the fact that here and there a guest appears in unconventional dress—a short coat or even a velvet working-jacket. For the rest there is the same gathering into clusters of three or four, the same inarticulate clatter of many voices that mark the most commonplace of gatherings.

But if one will withdraw to an inoffensive corner and take a critical view of the assembly, he will presently discover that many of the faces are familiar to him, although he supposed himself to be quite among strangers. The tall figure, with the beautiful, kindly face set in white hair and beard, has surely sat for the familiar portrait of Alfred Russel Wallace. This short, thick-set, robust, business-like figure is that of Sir Norman Lockyer. Yonder frail-seeming scholar, with white beard, is surely Professor Crookes. And this other scholar, with tall, rather angular frame and most kindly gleam of eye, is Sir Michael Foster; and there beyond is the large-seeming though not tall figure, and the round, rosy, youthful-seeming, beautifully benevolent face of Lord Lister. "What! a real lord there?" said a little American girl to whom I enumerated the company after my first visit to the Royal Society. "Then how did he act? Was he very proud and haughty, as if he could not speak to other people?" And I was happy to be able to reply that though Lord Lister, perhaps of all men living, would be most excusable did he carry in his manner the sense of his achievements and honors, yet in point of fact no man could conceivably be more free from any apparent self-consciousness. As one watches him now he is seen to pass from group to group with cordial hand-shake and pleasant word, clearly the most affable of men, lord though he be, and president of the Royal Society, and foremost scientist of his time.

Presently an attendant passed through the tearoom bearing a tremendous silver mace, perhaps five feet long, surmounted by a massive crown and cross, and looking like nothing so much as a "gigantic war-club." This is the mace which, when deposited on the president's desk in the lecture-room beyond, will signify that the society is in session. "It is the veritable mace," some one whispers at your elbow, "concerning which Cromwell gave his classical command to 'Remove that bauble.'" But since the mace was not made until 1663, some five years after Cromwell's death, this account may lack scientific accuracy. Be that as it may, this mace has held its own far more steadily than the fame of its alleged detractor, and its transportation through the tea-room is the only manner of announcement that the lecture is about to open in the hall beyond. Indeed, so inconspicuous is the proceeding, and so quietly do the members that choose to attend pass into the lecture-hall, leaving perhaps half the company engaged as before, that the "stranger "—as the non-member is here officially designated—might very readily fail to understand that the seance proper had begun. In any event, he cannot enter until permission has been formally voted by the society.

When he is allowed to enter he finds the meeting-room little different from the one he has left, except that it is provided with a sort of throne on a raised platform at one end and with cushioned benches for seats. On the throne, if one may so term it, sits Lord Lister, scarcely more than his head showing above what seems to be a great velvet cushion which surmounts his desk, at the base of which, in full view of the society, rests the mace, fixing the eye of the "stranger," as it is alleged to have fixed that of Cromwell aforetime, with a peculiar fascination. On a lower plane than the president, at his right and left, sit Sir Michael Foster and Professor Arthur William Rucker, the two permanent secretaries. At Sir Michael's right, and one stage nearer the audience, stands the lecturer, on the raised platform and behind the desk which extends clear across the front of the room. As it chances, the lecturer this afternoon is Professor Ehrlich, of Berlin and Frankfort-on-the-Main, who has been invited to deliver the Croonian lecture. He is speaking in German, and hence most of the fellows are assisting their ears by following the lecture in a printed translation, copies of which, in proof, were to be secured at the door.

The subject of the lecture is "Artificial Immunization from Disease." It is clear that the reader is followed with interested attention, which now and again gives rise to a subdued shuffle of applause.

The fact that the lecturer is speaking German serves perhaps to suggest even more vividly than might otherwise occur to one the contrast between this meeting and a meeting of the corresponding German society—the Royal Academy of Sciences at Berlin. Each is held in an old building of palatial cast and dimensions, of which Burlington House, here in Piccadilly, is much the older—dating from 1664—although its steam-heating and electric-lighting apparatus, when contrasted with the tile stoves and candles of the other, would not suggest this. For the rest, the rooms are not very dissimilar in general appearance, except for the platform and throne. But there the members of the society are shut off from the audience both by the physical barrier of the table and by the striking effect of their appearance in full dress, while here the fellows chiefly compose the audience, there being only a small company of "strangers" present, and these in no way to be distinguished by dress or location from the fellows themselves. It may be added that the custom of the French Academy of Sciences is intermediate between these two. There the visitors occupy seats apart, at the side of the beautiful hall, the main floor being reserved for members. But the members themselves are not otherwise distinguishable, and they come and go and converse together even during the reading of a paper almost as if this were a mere social gathering. As it is thus the least formal, the French meeting is also by far the most democratic of great scientific gatherings. Its doors are open to whoever may choose to enter. The number who avail themselves of this privilege is not large, but it includes, on occasions, men of varied social status and of diverse races and colors—none of whom, so far as I could ever discern, attracts the slightest attention.

At the German meeting, again, absolute silence reigns. No one thinks of leaving during the session, and to make any sound above a sigh would seem almost a sacrilege. But at the Royal Society an occasional auditor goes or comes, there are repeated audible signs of appreciation of the speaker's words, and at the close of the discourse there is vigorous and prolonged applause. There is also a debate, of the usual character, announced by the president, in which "strangers" are invited to participate, and to which the lecturer finally responds with a brief Nachwort, all of which is quite anomalous from the German or French stand-points. After that, however, the meeting is declared adjourned with as little formality in one case as in the others, and the fellows file leisurely out, while the attendant speedily removes the mace, in official token that the seance of the Royal Society is over.

THE LIBRARY AND READING-ROOM

But the "stranger" must not leave the building without mounting to the upper floor for an inspection of the library and reading-room. The rooms below were rather bare and inornate, contrasting unfavorably with the elegant meeting-room of the French institute. But this library makes full amends for anything that the other rooms may lack. It is one of the most charming—"enchanting" is the word that the Princess Christian is said to have used when she visited it recently—and perhaps quite the most inspiring room to be found in all London. It is not very large as library rooms go, but high, and with a balcony supported by Corinthian columns. The alcoves below are conventional enough, and the high tables down the centre, strewn with scientific periodicals in engaging disorder, are equally conventional. But the color-scheme of the decorations—sage-green and tawny—is harmonious and pleasing, and the effect of the whole is most reposeful and altogether delightful.

Chief distinction is given the room, however, by a row of busts on either side and by certain pieces of apparatus on the centre tables.

The busts, as will readily be surmised, are portraits of distinguished fellows of the Royal Society. There is, however, one exception to this, for one bust is that of a woman—Mary Somerville, translator of the Mecanique Celeste, and perhaps the most popular of the scientific writers of her time. It is almost superfluous to state that the row of busts begins with that of Newton. The place of honor opposite is held by that of Faraday. Encircling the room to join these two one sees, among others, the familiar visages of Dr. Gilbert; of Sir Joseph Banks, the famous surgeon of the early nineteenth century, who had the honor of being the only man that ever held the presidential chair of the Royal Society longer than it was held by Newton; of James Watts, of "steam-engine" fame; of Sabine, the astronomer, also a president of the society; and of Dr. Falconer and Sir Charles Lyell, the famous geologists.

There are numerous other busts in other rooms, some of them stowed away in nooks and crannies, and the list of those selected for the library does not, perhaps, suggest that this is the room of honor, unless, indeed, the presence of Newton and Faraday gives it that stamp. But in the presence of the images of these two, and of Lyell, to go no farther, one feels a certain sacredness in the surroundings.

If this is true of the mere marble images, what shall we say of the emblems on the centre table? That little tubular affair, mounted on a globe, the whole cased in a glass frame perhaps two feet high, is the first reflecting telescope ever made, and it was shaped by the hand of Isaac Newton. The brass mechanism at the end of the next table is the perfected air-pump of Robert Boyle, Newton's contemporary, one of the founders of the Royal Society and one of the most acute scientific minds of any time. And here between these two mementos is a higher apparatus, with crank and wheel and a large glass bulb that make it conspicuous. This is the electrical machine of Joseph Priestley. There are other mementos of Newton—a stone graven with a sun-dial, which he carved as a boy, on the paternal manor-house; a chair, said to have been his, guarded here by a silk cord against profanation; bits of the famous apple-tree which, as tradition will have it, aided so tangibly in the greatest of discoveries; and the manuscript of the Principia itself—done by the hand of an amanuensis, to be sure, but with interlinear corrections in the small, clear script of the master-hand itself. Here, too, is the famous death-mask, so much more interesting than any sculptured portrait, and differing so strangely in its broad-based nose and full, firm mouth from the over-refined lineaments of the sculptured bust close at hand. In a room not far away, to reach which one passes a score or two of portraits and as many busts of celebrities—including, by-the-bye, both bust and portrait of Benjamin Franklin—one finds a cabinet containing other mementos similar to those on the library tables. Here is the first model of Davy's safety-lamp; there a chronometer which aided Cook in his famous voyage round the world. This is Wollaston's celebrated "Thimble Battery." It will slip readily into the pocket, yet he jestingly showed it to a visitor as "his entire laboratory." That is a model of the double-decked boat made by Sir William Petty, and there beyond is a specimen of almost, if not quite, the first radiometer devised by Sir William Crookes.

As one stands in the presence of all these priceless relics, so vividly do the traditions of more than two centuries of science come to mind that one seems almost to have lived through them. One recalls, as if it were a personal recollection, the founding of the Royal Society itself in 1662, and the extraordinary scenes which the society witnessed during the years of its adolescence.

As one views the mementos of Boyle and Newton, one seems to be living in the close of the seventeenth century. It is a troublous time in England. Revolution has followed revolution. Commonwealth has supplanted monarchy and monarchy commonwealth. At last the "glorious revolution" of 1688 has placed a secure monarch on the throne. But now one external war follows another, and the new king, William of Orange, is leading the "Grand Alliance" against the French despot Louis XIV. There is war everywhere in Europe, and the treaty of Ryswick, in 1697, is but the preparation for the war of the Spanish Alliance, which will usher in the new century. But amid all this political turmoil the march of scientific discovery has gone serenely on; or, if not serenely, then steadily, and perhaps as serenely as could be hoped. Boyle has discovered the law of the elasticity of gases and a host of minor things. Robert Hooke is on the track of many marvels. But all else pales before the fact that Newton has just given to the world his marvellous law of gravitation, which has been published, with authority of the Royal Society, through the financial aid of Halley. The brilliant but erratic Hooke lias contested the priority of discovery and strenuously claimed a share in it. Halley eventually urges Newton to consider Hooke's claim in some of the details, and Newton yields to the extent of admitting that the great fact of gravitational force varying inversely as the square of the distance had been independently discovered by Hooke; but he includes also Halley himself and Sir Christopher Wren, along with Hooke, as equally independent discoverers of the same principle. To the twentieth-century consciousness it seems odd to hear Wren thus named as a scientific discoverer; but in truth the builder of St. Paul's began life as a professor of astronomy at Gresham College, and was the immediate predecessor of Newton himself in the presidential chair of the Royal Society. Now, at the very close of the seventeenth century, Boyle is recently dead, but Hooke, Wren, Halley, and Newton still survive: some of them are scarcely past their prime. It is a wonderful galaxy of stars of the first magnitude, and even should no other such names come in after-time, England's place among the scientific constellations is secure.

But now as we turn to the souvenirs of Cooke and Wollaston and Davy the scene shifts by a hundred years. We are standing now in the closing epoch of the eighteenth century. These again are troublous times. The great new colony in the West has just broken off from the parent swarm. Now all Europe is in turmoil. The French war-cloud casts its ominous shadow everywhere. Even in England mutterings of the French Revolution are not without an echo. The spirit of war is in the air. And yet, as before, the spirit of science also is in the air. The strain of the political relations does not prevent a perpetual exchange of courtesy between scientific men and scientific bodies of various nations. Davy's dictum that "science knows no country" is perpetually exemplified in practice. And at the Royal Society, to match the great figures that were upon the scene a century before, there are such men as the eccentric Cavendish, the profound Wollaston, the marvellously versatile Priestley, and the equally versatile and even keener-visioned Rumford. Here, too, are Herschel, who is giving the world a marvellous insight into the constitution of the universe; and Hutton, who for the first time gains a clear view of the architecture of our earth's crust; and Jenner, who is rescuing his fellow-men from the clutches of the most deadly of plagues; to say nothing of such titanic striplings as Young and Davy, who are just entering the scientific lists. With such a company about us we are surely justified in feeling that the glory of England as a scientific centre has not dimmed in these first hundred and thirty years of the Royal Society's existence.

And now, as we view the radiometer, the scene shifts by yet another century, and we come out of cloud-land and into our own proper age. We are at the close of the nineteenth century—no, I forget, we are fairly entering upon the twentieth. Need I say that these again are troublous times? Man still wages warfare on his fellow-man as he has done time out of mind; as he will do—who shall say how long? But meantime, as of yore, the men of science have kept steadily on their course. But recently here at the Royal Society were seen the familiar figures of Darwin and Lyell and Huxley and Tyndall. Nor need we shun any comparison with the past while the present lists can show such names as Wallace, Kelvin, Lister, Crookes, Foster, Evans, Rayleigh, Ramsay, and Lock-yer. What revolutionary advances these names connote! How little did those great men of the closing decades of the seventeenth and eighteenth centuries know of the momentous truths of organic evolution for which the names of Darwin and Wallace and Huxley stand! How little did they know a century ago, despite Hutton's clear prevision, of these marvellous slow revolutions through which, as Lyell taught us, the earth's crust had been built up! Not even Jen-ner could foresee a century ago the revolution in surgery which has been effected in our generation through the teachings of Lister.

And what did Rumford and Davy know of energy in its various manifestations as compared with the knowledge of to-day, of Crookes and Rayleigh and Ramsay and Kelvin? What would Joseph Priestley, the discoverer of oxygen, and Cavendish, the discoverer of nitrogen, think could they step into the laboratory of Professor Ramsay and see test-tubes containing argon and helium and krypton and neon and zenon? Could they more than vaguely understand the papers contributed in recent years to the Royal Society, in which Professor Ramsay explains how these new constituents of the atmosphere are obtained by experiments on liquid air. "Here," says Professor Ramsay, in effect, in a late paper to the society, "is the apparatus with which we liquefy hydrogen in order to separate neon from helium by liquefying the former while the helium still remains gaseous." Neon, helium, liquid air, liquid hydrogen—these would seem strange terms to the men who on discovering oxygen and nitrogen named them "dephlogisticated air" and "phlogisti-cated air" respectively.

Again, how elementary seems the teaching of Her-schel, wonderful though it was in its day, when compared with our present knowledge of the sidereal system as outlined in the theories of Sir Norman Lock-yer. Herschel studied the sun-spots, for example, with assiduity, and even suggested a possible connection between sun-spots and terrestrial weather. So far, then, he would not be surprised on hearing the announcement of Professor Lockyer's recent paper before the Royal Society on the connection between sun-spots and the rainfall in India. But when the paper goes on to speak of the actual chemical nature of the sun-spots, as tested by a spectroscope; to tell of a "cool" stage when the vapor of iron furnishes chief spectrum lines, and of a "hot" stage when the iron has presumably been dissociated into unknown "proto-iron" constituents—then indeed does it go far beyond the comprehension of the keenest eighteenth-century intellect, though keeping within the range of understanding of the mere scientific tyro of to-day.

Or yet again, consider a recent paper contributed by Professor Lockyer to the Royal Society, entitled "The New Star in Perseus: Preliminary Note"—referring to the new star that flashed suddenly on the vision of the terrestrial observers at more than first magnitude on February 22, 1901. This "star," the paper tells us, when studied by its spectrum, is seen to be due to the impact of two swarms of meteors out in space—swarms moving in different directions "with a differential velocity of something like seven hundred miles a second." Every astronomer of to-day understands how such a record is read from the displacement of lines on the spectrum, as recorded on the photographic negative. But imagine Sir William Herschel, roused from a century's slumber, listening to this paper, which involves a subject of which he was the first great master. "Ebulae," he might say; "yes, they were a specialty of mine; but swarms of meteors—I know nothing of these. And 'spectroscopes,' 'photographs'—what, pray, are these? In my day there were no such words or things as spectroscope and photograph; to my mind these words convey no meaning."

But why go farther? These imaginings suffice to point a moral that he who runs may read. Of a truth the march of science still goes on as it has gone on with steady tread throughout the long generations of the Royal Society's existence. If the society had giants among its members in the days of its childhood and adolescence, no less are there giants still to keep up its fame in the time of its maturity. The place of England among the scientific constellations is secure through tradition, but not through tradition alone.



III. THE ROYAL INSTITUTION AND THE LOW-TEMPERATURE RESEARCHES

FOUNDATION AND FOUNDER

"GEORGE THE THIRD, by the Grace of God King of Great Britain, France, and Ireland, Defender of the Faith, etc., to all to whom these presents shall come, greeting. Whereas several of our loving subjects are desirous of forming a Public Institution for diffusing the knowledge and facilitating the general introduction of Useful Mechanical Inventions and Improvements; and for teaching, by Courses of Philosophical Lectures and Experiments, the Application of Science to the Common Purposes of Life, we do hereby give and grant"—multifarious things which need not here be quoted. Such are the opening words of the charter with which, a little more than a century ago, the Royal Institution of Great Britain came into existence and received its legal christening. If one reads on he finds that the things thus graciously "given and granted," despite all the official verbiage, amount to nothing more than royal sanction and approval, but doubtless that meant more in the way of assuring popular approval than might at first glimpse appear. So, too, of the list of earls, baronets, and the like, who appear as officers and managers of the undertaking, and who are described in the charter as "our right trusty and right well-beloved cousins," "our right trusty and well-beloved counsellors," and so on, in the skilfully graduated language of diplomacy. The institution that had the King for patron and such notables for officers seemed assured a bright career from the very beginning. In name and in personnel it had the flavor of aristocracy, a flavor that never palls on British palate. And right well the institution has fulfilled its promise, though in a far different way from what its originator and founder anticipated.

Its originator and founder, I say, and say advisedly; for, of course, here, as always, there is one man who is the true heart and soul of the movement, one name that stands, in truth, for the whole project, and to which all the other names are mere appendages. You would never suspect which name it is, in the present case, from a study of the charter, for it appears well down the file of graded titles, after "cousins" and "counsellors" have had their day, and is noted simply as "our trusty and well-beloved Benjamin, Count of Rumford, of the Holy Roman Empire." Little as there is to signalize it in the charter, this is the name of the sole projector of the enterprise in its incipiency, of the projector of every detail, of the writer of the charter itself even. The establishment thus launched with royal title might with full propriety have been called, as indeed it sometimes is called, the Rumford Institution.

The man who thus became the founder of this remarkable institution was in many ways a most extraordinary person. He was an American by birth, and if not the most remarkable of Americans, he surely was destined to a more picturesque career than ever fell to the lot of any of his countrymen of like eminence. Born on a Massachusetts farm, he was a typical "down-east Yankee," with genius added to the usual shrewd, inquiring mind and native resourcefulness. He was self-educated and self-made in the fullest sense in which those terms can be applied. At fourteen he was an unschooled grocer-lad—Benjamin Thompson by name—in a little New England village; at forty he was a world-famous savant, as facile with French, Italian, Spanish, and German as with his native tongue; he had become vice-president and medallist of the Royal Society, member of the Berlin National Academy of Science, of the French Institute, of the American Academy of Science, and I know not what other learned bodies; he had been knighted in Great Britain after serving there as under-secretary of state and as an officer; and he had risen in Bavaria to be more than half a king in power, with the titles, among others, of privy councillor of state, and head of the war department, lieutenant-general of the Bavarian armies, holder of the Polish order of St. Stanislas and the Bavarian order of the White Eagle, ambassador to England and to France, and, finally, count of the Holy Roman Empire. Once, in a time of crisis, Rumford was actually left at the head of a council of regency, in full charge of Bavarian affairs, the elector having fled. The Yankee grocer-boy had become more than half a king.

Never, perhaps, did a man of equal scientific attainments enjoy a corresponding political power. Never was political power wielded more justly by any man.

For in the midst of all his political and military triumphs, Rumford remained at heart to the very end the scientist and humanitarian. He wielded power for the good of mankind; he was not merely a ruler but a public educator. He taught the people of Bavaria economy and Yankee thrift. He established kitchens for feeding the poor on a plan that was adopted all over Europe; but, better yet, he created also workshops for their employment and pleasure-gardens for their recreation. He actually banished beggary from the principality.

It was in the hope of doing in some measure for London what he had done for Munich that this large-brained and large-hearted man was led to the project of the Royal Institution. He first discussed his plans with a committee of the Society for Alleviating the Condition of the Poor, for it was the poor, the lower ranks of society, whom he wished chiefly to benefit. But he knew that to accomplish his object, he must work through the aristocratic channels; hence the name of the establishment and the charter with its list of notables. The word institution was selected by Rumford, after much deliberation, as, on the whole, the least objectionable title for the establishment, as having a general inclusiveness not possessed by such words as school or college. Yet in effect it was a school which Rumford intended to found—a school for the general diffusion of useful knowledge. There were to be classes for mechanics, and workshops, kitchens, and model-rooms, where the "application of science to the useful purposes of life" might be directly and practically taught; also a laboratory for more technical investigations, with a "professor" in charge, who should also deliver popular lectures on science. Finally, there was to be a scientific library.

All these aims were put into effect almost from the beginning. The necessary funds were supplied solely by popular subscription and by the sale of lecture tickets (as all funds of the institution have been ever since), and before the close of the year 1800 Rumford's dream had become an actuality—as this practical man's dreams nearly always did. The new machine did not move altogether without friction, of course, but on the whole all went well for the first few years. The institution had found a local habitation in a large building in Albemarle Street, the same building which it still occupies, and for a time Rumford lived there and gave the enterprise his undivided attention. He appointed the brilliant young Humphry Davy to the professorship of chemistry, and the even more wonderful Thomas Young to that of natural philosophy. He saw the workshops and kitchens and model-rooms in running order—the entire enterprise fully launched. Then other affairs, particularly an attachment for a French lady, the widow of the famous chemist Lavoisier (whom he subsequently married, to his sorrow), called him away from England never to return. And the first chapter in the history of the Royal Institution was finished.

METHOD AND RESULT

Rumford, the humanitarian, gone, a curious change came over the spirit of the enterprise he had founded. The aristocrats who at first were merely ballast for the enterprise now made their influence felt. With true British reserve, they announced their belief that the education of the masses involved a dangerous political tendency. Hence the mechanics' school was suspended and the workshops and kitchens abolished; in a word, the chief ends for which the institution was founded were annulled. The library and the lectures remained, to be sure, but they were for the amusement of the rich, not for the betterment of the poor. It was the West End that made a fad of the institution and a society function of the lectures of Sydney Smith and of the charming youth Davy. Thus the institution came to justify its aristocratic title and its regal patronage; and the poor seemed quite forgotten.

But indeed the institution itself was poor enough in these days, after the first flush of enthusiasm died away, and it is but fair to remember that without the support of its popular lectures its very existence would have been threatened. Nor in any event are regrets much in order over the possible might-have-beens of an institution whose laboratories were the seat of the physical investigations of Thomas Young, through which the wave theory of light first gained a footing, and of the brilliant chemical researches of Davy, which practically founded the science of electro-chemistry and gave the chemical world first knowledge of a galaxy of hitherto unknown elements. Through the labors of these men, and through the popular lecture-courses delivered at the institution by such other notables of science as Wollaston, Dalton, and Rum-ford, the enterprise had become world-famous before the close of the first decade of its existence.

From that day till this the character of the Royal Institution has not greatly changed. The enterprise shifted around during its earliest years, while it was gaining its place in the scheme of things; but once that was found, like a true British institution it held its course with an inertia that a mere century of time could not be expected to alter. Rumford was the sole founder of the enterprise, but it was Davy who gave it the final and definitive cast. He it was who established the tradition that the Royal Institution was to be essentially a laboratory for brilliant original investigations, the investigator to deliver a yearly course of lectures, but to be otherwise untrammelled. It occupied, and has continued to occupy, the anomalous position of a school to which pupils are on no account admitted, and whose professors teach nothing except by a brief course of lectures to which whoever cares to pay the admission price may freely enter.

But the marvellous results achieved at the Royal Institution have more than justified the existence of so anomalous an enterprise. Superlatives are always dangerous, but it may well be doubted whether there is another single institution in the world where so many novel original discoveries in physical science have been made as have been brought to light in the laboratories of the building on Albemarle Street during this first century of its occupancy; for practically all that is to be credited to Thomas Young, Humphry Davy, Michael Faraday, and John Tyndall, not to mention living investigators, is to be credited also to the Royal Institution, whose professorial chairs these great men have successively occupied. Davy spent here the best years of his youth and prime. Faraday, his direct successor, came to the institution in a subordinate capacity as a mere boy, and was the life of the institution for half a century. Tyndall gave it forty years of service. What wonder, then, that the Briton speaks of the institution as the "Pantheon of Science"?

If you visit the Royal Institution to-day you will find it in most exterior respects not unlike what it presumably was a century ago. Its long, stone front, dinged with age, with its somewhat Pantheon-like colonnade, has an appearance of dignity rather than of striking impressiveness. The main entrance, jutting full on the sidewalk, is at the street level, and the glass door gives hospitable glimpses of the interior. Entering, one finds himself in a main central hall, at the foot of the main central staircase. The air of eminent respectability so characteristic of the British institution is over all; likewise the pervasive hush of British reserve. But you will not miss also the atmosphere of sincere if uneffusive British courtesy.

At your right, as you mount the stairway, is a large statue of Faraday; on the wall right ahead is a bronze medallion of Tyndall, placed beneath a large portrait of Davy. At the turn of the stairs is a marble bust of Wollaston. Farther on, in hall and library, you will find other busts of Faraday, other portraits of Davy; portraits of Faraday everywhere, and various other busts of notables who have had connection with the institution. You will be shown the lecture-hall where Davy, Faraday, and Tyndall pronounced their marvellous discourses; the arrangement, the seats, the cushions even if appearances speak truly, and certainly the lecture-desk itself, unchanged within the century. You may see the crude balance, clumsy indeed to modern eyes, with which Davy performed his wonders. The names and the memories of three great men—Davy, Faraday, and Tyndall—will be incessantly before you, and the least impressionable person could not well escape a certain sense of consecration of his surroundings. The hush that is over everything seems but fitting.

All that is as it should be. But there are other memories connected with these surroundings which are not so tangibly presented to the senses. For where, amid all these busts and portraits, is the image of that other great man, the founder of the institution, the sole originator of the enterprise which has made possible the aggregation of all these names and these memories? Where are the remembrances of that extraordinary man whom the original charter describes as "our well-beloved Benjamin, Count of Rumford?" Well, you will find a portrait of him, it is true, if you search far enough, hung high above a doorway in a room with other portraits. But one finds it hard to escape the feeling that there has been just a trifling miscarriage of justice in the disposal. Doubtless there was no such intention, but the truth seems to be that the glamour of the newer fame of Faraday has dazzled a little the eyes of the rulers of the institution of the present generation. But that, after all, is a small matter about which to quibble. There is glory enough for all in the Royal Institution, and the disposal of busts and portraits is unworthy to be mentioned in connection with the lasting fame of the great men who are here in question. It would matter little if there were no portrait at all of Rumford here, for all the world knows that the Royal Institution itself is in effect his monument. His name will always be linked in scientific annals with the names of Young, Davy, Faraday, and Tyndall. And it is worthy such association, for neither in native genius nor in realized accomplishments was Rumford inferior to these successors.

FROM LIQUID CHLORINE TO LIQUID HYDROGEN

Nor is it merely by mutual association with the history of the Royal Institution that these great names are linked. There was a curious and even more lasting bond between them in the character of their scientific discoveries. They were all pioneers in the study of those manifestations of molecular activity which we now, following Young himself, term energy. Thus Rumford, Davy, and Young stood almost alone among the prominent scientists of the world at the beginning of the century in upholding the idea that heat is not a material substance—a chemical element—but merely a manifestation of the activities of particles of matter. Rumford's papers on this thesis, communicated to the Royal Society, were almost the first widely heralded claims for this then novel idea. Then Davy came forward in support of Rumford, with his famous experiment of melting ice by friction. It was perhaps this intellectual affinity that led Rumford to select Davy for the professorship at the Royal Institution, and thus in a sense to predetermine the character of the scientific work that should be accomplished there—the impulse which Davy himself received from Rum-ford being passed on to his pupil Faraday. There is, then, an intangible but none the less potent web of association between the scientific work of Rumford and some of the most important researches that were conducted at the Royal Institution long years after his death; and one is led to feel that it was not merely a coincidence that some of Faraday's most important labors should have served to place on a firm footing the thesis for which Rumford battled; and that Tyndall should have been the first in his "beautiful book" called Heat, a Mode of Motion, to give wide popular announcement to the fact that at last the scientific world had accepted the proposition which Rumford had vainly demonstrated three-quarters of a century before.

This same web of association extends just as clearly to the most important work which has been done at the Royal Institution in the present generation, and which is still being prosecuted there—the work, namely, of Professor James Dewar on the properties of matter at excessively low temperatures. Indeed, this work is in the clearest sense a direct continuation of researches which Davy and Faraday inaugurated in 1823 and which Faraday continued in 1844. In the former year Faraday, acting on a suggestion of Davy's, performed an experiment which resulted in the production of a "clear yellow oil" which was presently proved to be liquid chlorine. Now chlorine, in its pure state, had previously been known (except in a forgotten experiment of Northmore's) only as a gas. Its transmutation into liquid form was therefore regarded as a very startling phenomenon. But the clew thus gained, other gases were subjected to similar conditions by Davy, and particularly by Faraday, with the result that several of them, including sulphurous, carbonic, and hydrochloric acids were liquefied. The method employed, stated in familiar terms, was the application of cold and of pressure. The results went far towards justifying an extraordinary prediction made by that extraordinary man, John Dalton, as long ago as 1801, to the effect that by sufficient cooling and compressing all gases might be transformed into liquids—a conclusion to which Dalton had vaulted, with the sureness of supreme genius, from his famous studies of the properties of aqueous vapor.

Between Dalton's theoretical conclusion, however, and experimental demonstration there was a tremendous gap, which the means at the disposal of the scientific world in 1823 did not enable Davy and Faraday more than partially to bridge. A long list of gases, including the familiar oxygen, hydrogen, and nitrogen, resisted all their efforts utterly—notwithstanding the facility with which hydrogen and oxygen are liquefied when combined in the form of water-vapor, and the relative ease with which nitrogen and hydrogen, combined to form ammonia, could also be liquefied. Davy and Faraday were well satisfied of the truth of Dalton's proposition, but they saw the futility of further efforts to put it into effect until new means of producing, on the one hand, greater pressures, and, on the other, more extreme degrees of cold, should be practically available. So the experiments of 1823 were abandoned.

But in 1844 Faraday returned to them, armed now with new weapons, in the way of better air-pumps and colder freezing mixtures, which the labors of other workers, chiefly Thilorier, Mitchell, and Natterer, had made available. With these new means, and without the application of any principle other than the use of cold and pressure as before, Faraday now succeeded in reducing to the liquid form all the gases then known with the exception of six; while a large number of these substances were still further reduced, by the application of the extreme degrees of cold now attained, to the condition of solids. The six gases which still proved intractable, and which hence came to be spoken of as "permanent gases," were nitrous oxide, marsh gas, carbonic oxide, oxygen, nitrogen, and hydrogen.

These six refractory gases now became a target for the experiments of a host of workers in all parts of the world. The resources of mechanical ingenuity of the time were exhausted in the effort to produce low temperatures on the one hand and high pressures on the other. Thus Andrews, in England, using the bath of solid carbonic acid and ether which Thilorier had discovered, and which produces a degree of cold of—80 deg. Centigrade, applied a pressure of five hundred atmospheres, or nearly four tons to the square inch, without producing any change of state. Natterer increased this pressure to two thousand seven hundred atmospheres, or twenty-one tons to the square inch, with the same negative results. The result of Andrews' experiments in particular was the final proof of what Cagniard de la Tour had early suspected and Faraday had firmly believed, that pressure alone, regardless of temperature, is not sufficient to reduce a gas to the liquid state. In other words, the fact of a so-called "critical temperature," varying for different substances, above which a given substance is always a gas, regardless of pressure, was definitively discovered. It became clear, then, that before the resistant gases would be liquefied means of reaching extremely low temperatures must be discovered. And for this, what was needed was not so much new principles as elaborate and costly machinery for the application of a principle long familiar—the principle, namely, that an evaporating liquid reduces the temperature of its immediate surroundings, including its own substance.

Ingenious means of applying this principle, in connection with the means previously employed, were developed independently by Pictet in Geneva and Cailletet in Paris, and a little later by the Cracow professors Wroblewski and Olzewski, also working independently. Pictet, working on a commercial scale, employed a series of liquefied gases to gain lower and lower temperatures by successive stages. Evaporating sulphurous acid liquefied carbonic acid, and this in evaporating brought oxygen under pressure to near its liquefaction point; and, the pressure being suddenly released (a method employed in Faraday's earliest experiments), the rapid expansion of the compressed oxygen liquefies a portion of its substance. This result was obtained in 1877 by Pictet and Cailletet almost simultaneously. Cailletet had also liquefied the newly discovered acetylene gas. Five years later Wroblewski liquefied marsh gas, and the following year nitrogen; while carbonic oxide and nitrous oxide yielded to Olzewski in 1884. Thus forty years of effort had been required to conquer five of Faraday's refractory gases, and the sixth, hydrogen, still remains resistant. Hydrogen had, indeed, been seen to assume the form of visible vapor, but it had not been reduced to the so-called static state—that is, the droplets had not been collected in an appreciable quantity, as water is collected in a cup. Until this should be done, the final problem of the liquefaction of hydrogen could not be regarded as satisfactorily solved.

More than another decade was required to make this final step in the completion, of Faraday's work. And, oddly enough, yet very fittingly, it was reserved for Faraday's successor in the chair at the Royal Institution to effect this culmination. Since 1884 Professor Dewar's work has made the Royal Institution again the centre of low-temperature research. By means of improved machinery and of ingenious devices for shielding the substance operated on from the accession of heat, to which reference will be made more in detail presently, Professor Dewar was able to liquefy the gas fluorine, recently isolated by Moussan, and the recently discovered gas helium in 1897. And in May, 1898, he was able to announce that hydrogen also had yielded, and for the first time in the history of science that* elusive substance, hitherto "permanently" gaseous, was held as a tangible liquid in a cuplike receptacle; and this closing scene of the long struggle was enacted in the same laboratory in which Faraday performed the first liquefaction experiment with chlorine just three-quarters of a century before.

It must be noted, however, that this final stage in the liquefaction struggle was not effected through the use of the principle of evaporating liquids which has just been referred to, but by the application of a quite different principle and its elaboration into a perfectly novel method. This principle is the one established long ago by Joule and Thomson (Lord Kelvin), that compressed gases when allowed to expand freely are lowered in temperature. In this well-known principle the means was at hand greatly to simplify and improve the method of liquefaction of gases, only for a long time no one recognized the fact. Finally, however, the idea had occurred to two men almost simultaneously and quite independently. One of these was Professor Linde, the well-known German experimenter with refrigeration processes; the other, Dr. William Hampson, a young English physician. Each of these men conceived the idea—and ultimately elaborated it in practice—of accumulating the cooling effect of an expanding gas by allowing the expansion to take place through a small orifice into a chamber in which the coil containing the compressed gas was held. In Dr. Hampson's words:

"The method consists in directing all the gas immediately after its expansion over the coils which contain the compressed gas that is on its way to the expansion-point. The cold developed by expansion in the first expanded gas is thus communicated to the oncoming compressed gas, which consequently expands from, and therefore to, a lower temperature than the preceding portion. It communicates in the same way its own intensified cold to the succeeding portion of compressed gas, which, in its turn, is made colder, both before and after expansion, than any that had gone before. This intensification of cooling goes on until the expansion-temperature is far lower than it was at starting; and if the apparatus be well arranged the effect is so powerful that even the smaller amount of cooling due to the free expansion of gas through a throttle-valve, though pronounced by Siemens and Coleman incapable of being utilized, may be made to liquefy air without using other refrigerants."

So well is this principle carried out in Dr. Hamp-son's apparatus for liquefying air that compressed air passing into the coil at ordinary temperature without other means of refrigeration begins to liquefy in about six minutes—a result that seems almost miraculous when it is understood that the essential mechanism by which this is brought about is contained in a cylinder only eighteen inches long and seven inches in diameter.

As has been said, it was by adopting this principle of self-intensive refrigeration that Professor Dewar was able to liquefy hydrogen. More recently the same result has been attained through use of the same principle by Professor Ramsay and Dr. Travers at University College, London, who are to be credited also with first publishing a detailed account of the various stages of the process. It appears that the use of the self-intensification principle alone is not sufficient with hydrogen as it is with the less volatile gases, including air, for the reason that at all ordinary temperatures hydrogen does not cool in expanding, but actually becomes warmer. It is only after the compressed hydrogen has been cooled by immersion in refrigerating media of very low temperature that this gas becomes amenable to the law of cooling on expansion. In the apparatus used at University College the coil of compressed hydrogen is passed successively through (1) a jar containing alcohol and solid carbonic acid at a temperature of—80 deg. Centigrade; (2) a chamber containing liquid air at atmospheric pressure, and (3) liquid air boiling in a vacuum bringing the temperature to perhaps 2050 Centigrade before entering the Hampson coil, in which expansion and the self-intensive refrigeration lead to actual liquefaction. With this apparatus Dr. Travers succeeded in producing an abundant quantity of liquid hydrogen for use in the experiments on the new gases that were first discovered in the same laboratory through the experiments on liquid air—gases about which I shall have something more to say in another chapter.

PRINCIPLES AND EXPERIMENTS

At first blush it seems a very marvellous thing, this liquefaction of substances that under all ordinary conditions are gaseous. It is certainly a little startling to have a cup of clear, water-like liquid offered one, with the assurance that it is nothing but air; still more so to have the same air presented in the form of a white "avalanche snow." In a certain sense it is marvellous, because the mechanical difficulties that have been overcome in reducing the air to these unusual conditions are great. Yet, in another and broader view, there is nothing more wonderful about liquid air than about liquid water, or liquid mercury, or liquid iron. Long before air was actually liquefied, it was perfectly understood by men of science that under certain conditions it could be liquefied just as surely as water, mercury, iron, and every other substance could be brought to a similar state. This being known, and the principles involved understood, had there been nothing more involved than the bare effort to realize these conditions all the recent low-temperature work would have been mere scientific child's-play, and liquid air would be but a toy of science. But in point of fact there are many other things than this involved; new principles were being searched for and found in the course of the application of the old ones; new light was being thrown into many dark corners; new fields of research, some of them as yet barely entered, were being thrown open to the investigator; new applications of energy, of vast importance not merely in pure science but in commercial life as well, were being made available. That is why the low-temperature work must be regarded as one of the most important scientific accomplishments of our century.

At the very outset it was this work in large measure which gave the final answer to the long-mooted question as to the nature of heat, demonstrating the correctness of Count Rumford's view that heat is only a condition not itself a substance. Since about the middle of the century this view, known as the mechanical theory of heat, has been the constant guide of the physicists in all their experiments, and any one who would understand the low-temperature phenomena must keep this conception of the nature of heat clearly and constantly in mind. To understand the theory, one must think of all matter as composed of minute isolated particles or molecules, which are always in motion—vibrating, if you will. He must mentally magnify and visualize these particles till he sees them quivering before him, like tuning-forks held in the hand. Remember, then, that, like the tuning-fork, each molecule would, if left to itself, quiver less and less violently, until it ran down altogether, but that the motion thus lessening is not really lost. It is sent out in the form of ether waves, which can set up like motion in any other particles which they reach, be they near or remote; or it is transmitted as a direct push—a kick, if you will—to any other particle with which the molecule comes in physical contact.

But note now, further, that our molecule, while incessantly giving out its energy of motion in ether waves and in direct pushes, is at the same time just as ceaslessly receiving motion from the ether waves made by other atoms, and by the return push of the molecules against which it pushes. In a word, then, every molecule of matter is at once a centre for the distribution of motion (sending out impulses which affect, sooner or later, every other atom of matter in the universe), and, from the other point of view, also a centre for the reception of motion from every direction and from every other particle of matter in the universe. Whether any given molecule will on the whole gain motion or lose it depends clearly on the simple mechanical principles of give and take.

From equally familiar mechanical principles, it is clear that our vibrating molecule, in virtue of its vibrations, is elastic, tending to be thrown back from every other molecule with which it comes in contact, just as a vibrating tuning-fork kicks itself away from anything it touches. And of course the vigor of the recoil will depend upon the vigor of the vibration and the previous movements. But since these movements constitute temperature, this is another way of saying that the higher the temperature of a body the more its molecules will tend to spring asunder, such separation in the aggregate constituting expansion of the mass as a whole. Thus the familiar fact of expansion of a body under increased temperature is explained.

But now, since all molecules are vibrating, and so tending to separate, it is clear that no unconfined mass of molecules would long remain in contiguity unless some counter influence tended to draw them together. Such a counter influence in fact exists, and is termed the "force" of cohesion. This force is a veritable gravitation influence, drawing every molecule towards every other molecule. Possibly it is identical with gravitation. It seems subject to some law of decreasing in power with the square of the distance; or, at any rate, it clearly becomes less potent as the distance through which it operates increases.

Now, between this force of cohesion which tends to draw the molecules together, and the heat vibrations which tend to throw the molecules farther asunder, there seems to be an incessant battle. If cohesion prevails, the molecules are held for the time into a relatively fixed system, which we term the solid state. If the two forces about balance each other, the molecules move among themselves more freely but maintain an average distance, and we term the condition the liquid state. But if the heat impulse preponderates, the molecules (unless restrained from without) fly farther and farther asunder, moving so actively that when they collide the recoil is too great to be checked by cohesion, and this condition we term the gaseous state.

Now after this statement, it is clear that what the low-temperature worker does when he would liquefy a gas is to become the champion of the force of cohesion. He cannot directly aid it, for so far as is known it is an unalterable quantity, like gravitation. But he can accomplish the same thing indirectly by weakening the power of the rival force. Thus, if he encloses a portion of gas in a cylinder and drives a piston down against it, he is virtually aiding cohesion by forcing the molecules closer together, so that the hold of cohesion, acting through a less distance, is stronger. What he accomplishes here is not all gain, however, for the bounding molecules, thus jammed together, come in collision with one another more and more frequently, and thus their average activity of vibration is increased and not diminished; in other words, the temperature of the gas has risen in virtue of the compression. Compression alone, then, will not avail to enable cohesion to win the battle.

But the physicist has another resource. He may place the cylinder of gas in a cold medium, so that the heat vibrations sent into it will be less vigorous than those it sends out. That is a blow the molecule cannot withstand. It is quite impotent to cease sending out the impulses however little comes in return; hence the aggregate motion becomes less and less active, until finally the molecule is moving so sluggishly that when it collides with its fellow cohesion is able to hold it there. Cohesion, then, has won the battle, and the gas has become a liquid.

Such, stated in terms of the mechanical theory of heat, is what is brought to pass when a gas is liquefied in the laboratory of the physicist. It remains only to note that different chemical substances show the widest diversity as to the exact point of temperature at which this balance of the expansive and cohesive tendencies is affected, but that the point, under uniform conditions of pressure, is always the same for the same substance. This diversity has to do pretty clearly with the size of the individual molecules involved; but its exact explanation is not yet forthcoming, and, except in a general way, the physicist would not be able to predict the "critical temperature" of any new gas presented to him. But once this has been determined by experiment, he always knows just what to expect of any given substance. He knows, for example, that in a mixture of gases hydrogen would still remain gaseous after all the others had assumed the liquid state, and most of them the solid state as well.

These mechanical conceptions well in mind, it is clear that what the would-be liquefier of gases has all along sought to attain is merely the insulation of the portion of matter with which he worked against the access of heat-impulse from its environment. It is clear that were any texture known which would permit a heat-impulse to pass through it in one direction only, nothing more would be necessary than to place a portion of gas in such a receptacle of this substance, so faced as to permit egress but not entrance of the heat, and the gas thus enclosed, were it hydrogen itself, would very soon become liquid and solid, through spontaneous giving off of its energy, without any manipulation whatever. Contrariwise, were the faces of the receptacle reversed, a piece of iron placed within it would be made red-hot and melted though the receptacle were kept packed in salt and ice and no heat applied except such as came from this freezing mixture. One could cook a beefsteak with a cake of ice had he but such a material as this with which to make his stove. Not even Rumford or our modern Edward Atkinson ever dreamed of such economy of fuel as that.

But, unfortunately, no such substance as this is known, nor, indeed, any substance that will fully prevent the passage of heat-impulses in either direction. Hence one of the greatest tasks of the experimenters has been to find a receptacle that would insulate a cooled substance even partially from the incessant bombardment of heat-impulses from without. It is obvious that unless such an insulating receptacle could be provided none of the more resistent gases, such as oxygen, could be long kept liquid, even when once brought to that condition, since an environment of requisite frigidity could not practicably be provided.

But now another phase of the problem presents itself to the experimenter. Oxygen has assumed the quiescent liquid state, to be sure, but in so doing it has fallen below the temperature of its cooling medium; hence it is now receiving from that medium more energy of vibration than it gives, and unless this is prevented very soon its particles will again have power to kick themselves apart and resume the gaseous state. Something, then, must be done to insulate the liquefied gas, else it will retain the liquid state for too short a time to be much experimented with. How might such insulation be accomplished?

The most successful attack upon this important problem has been made by Professor Dewar. He invented a receptacle for holding liquefied gases which, while not fulfilling the ideal conditions referred to above, yet accomplishes a very remarkable degree of heat insulation. In consists of a glass vessel with double walls, the space between which is rendered a vacuum of the highest practicable degree. This vacuum, containing practically no particles of matter, cannot, of course, convey heat-impulses to or from the matter in the receptacle with any degree of rapidity. Thus one of the two possible means of heat transfer is shut off and a degree of insulation afforded the liquefied substance. But of course the other channel, ether radiation, remains. Even this may be blocked to a large extent, however, by leaving a trace of mercury vapor in the vacuum space, which will be deposited as a fine mirror on the inner surface of the chamber. This mirror serves as an admirable reflector of the heat-rays that traverse the vacuum, sending more than half of them back again. So, by the combined action of vacuum and mirror, the amount of heat that can penetrate to the interior of the receptacle is reduced to about one-thirtieth of what would enter an ordinary vessel. In other words, a quantity of liquefied gas which would evaporate in one minute from an ordinary vessel will last half an hour in one of Professor Dewar's best vacuum vessels. Thus in one of these vessels a quantity of liquefied air, for example, can be kept for a considerable time in an atmosphere at ordinary temperature, and will only volatilize at the surface, like water under the same conditions, though of course more rapidly; whereas the same liquid in an ordinary vessel would boil briskly away, like water over a fire. Only, be it remembered, the air in "boiling" is at a temperature of about one hundred and eighty degrees below zero, so that it would instantly freeze almost any substance placed into it. A portion of alcohol poured on its surface will be changed quickly into a globule of ice, which will rattle about the sides of the vessel like a marble. That is not what one ordinarily thinks of as a "boiling" temperature.

If the vacuum vessel containing a liquefied gas be kept in a cold medium, and particularly if two vacuum tubes be placed together, so that no exposed surface of liquid remains, a portion of liquefied air, for example, may be kept almost indefinitely. Thus it becomes possible to utilize the liquefied gas for experimental investigation of the properties of matter at low temperatures that otherwise would be quite impracticable. Great numbers of such experiments have been performed in the past decade or so by all the workers with low temperatures already mentioned, and by various others, including, fittingly enough, the holder of the Rumford professorship of experimental physics at Harvard, Professor Trowbridge. The work of Professor Dewar has perhaps been the most comprehensive and varied, but the researches of Pictet, Wroblewski, and Olzewski have also been important, and it is not always possible to apportion credit for the various discoveries accurately, since the authorities themselves are in unfortunate disagreement in several questions of priority. But in any event, such questions of exact priority have no great interest for any one but the persons directly involved. We may quite disregard them here, confining attention to the results themselves, which are full of interest.