poussée." But they occurred on a much smaller scale, and there was no reason why the phenomena should be considered otherwise than as quite exceptional. To recognize the generality of that class of stratigraphical accidents was a conquest of a high order, not only for Scottish geology, but for all countries where the work of orogenetic disturbances has for a long time suffered from the agencies of erosion. The Highlands of Scotland belong to that part of the old European continent which in earlier Palæozoic times emerged from the sea. Near the end of the Silurian period it was subjected to enormous pressure, which resulted in folding and breaking the whole border of the dry land, raising in the air a series of high mountainous ridges, the Caledonian chain of M. Suess. But millions of years have since passed over the land, and the continued action of atmospheric powers has left but a very small part of the original mass. It is extremely difficult, therefore, to restore the broken continuity; and through the quiet appearance of the now planed ground, the geologist is everywhere bound to search after the scattered signs of previous plication and fracture. This is now the task to be fulfilled by the detailed Survey, and every stratigraphical difficulty has to be treated in the newly-acquired light.

A few years after that discovery had been made in Scotland, Prof. Marcel Bertrand made in Southern France quite similar observations, showing that very limited patches of older formations, which had been till then regarded as remnants of ancient islets, projecting out of younger geological seas, were nothing else than outliers of reversed folds, the remainder of which had disappeared under the action of rain and rivers.

In this manner the correction of a long accepted error has led to stratigraphical conclusions of the highest import. In the meantime these gigantic displacements showed themselves accompanied by intense modifications of the rocks, so that Geikie was entitled to write: "In exchange for this abandoned belief, we are presented with startling new evidence of regional metamorphism on a colossal scale, and are admitted some way into the secret of the processes whereby it has been produced."

This is not the only occasion on which Sir Archibald has given proof of his readiness to admit frankly and decidedly the correction of opinions which have long been held. Some years ago, when the Lower Cambrian fauna had been detected by the officers of the Survey much below the Durness limestone of the Highlands, in a series of strata which rests unconformably on the Torridon sandstone, he was the first to announce the fact before the Geological Society. The "Precambrian," which he had till then been rather reluctant to recognize, has now taken its place in the scale of divisions. Moreover, he has created a new name, that of "Dalradian," for the long strip of Precambrian deposits which extends from Donegal to the centre and south-west of Scotland.

As one of the most characteristic formations in Scotland is the Old Red Sandstone, we cannot be surprised that Sir Archibald has devoted much care to the description of the peculiarities of that interesting group of strata. After a long and detailed study of the whole ground, he has summed up his views in some important memoirs, published in the Transactions of the Royal Society of Edinburgh. There he has called again to life the

old and long-extinct lakes, where the grits and glomerates of the Old Red were piled up through disintegration of surrounding formations, namely, L Orcadie, Lake Caledonia, Lake Cheviot, Welsh L. and Lake of Lorne; each of them being a separate be where the work of sedimentation has been mary interrupted by volcanic outbursts, while in the adjar and more quiet seas there were accumulated the deposits of Devonshire.

But the chief work of Sir Archibald seems to be: exhaustive review of the volcanic history of the Br Isles. While his brother, Dr. James Geikie, the ar of "The Great Ice Age," has done excellent servic. deciphering the marks of former ice action on the s the United Kingdom, Sir Archibald has been partici attracted by the work of fire, i.e. by the records of volcanic activity, the evidence of which is so deeply: pressed on the scenery of the Hebrides, of Wales, other districts of Great Britain.

The British Isles are now a very quiet ground, var explosive activity and projection of stones seem to r restricted to electoral periods; and although Scotland been from time to time shaken by minor earthquakes human eye has ever seen there any volcanic oath Nevertheless, during Tertiary times, immense shees lava were poured out in the north-west of the com To discern the site of the centres of eruption, and c mine the old chimneys, the remnants of which give glimpse into the lowest parts of ascending lavas discriminate the volcanic necks, the intrusive sheets dykes, the bedded lavas and the tuffs-this was thei part of the task undertaken by Sir Archibald. B was not enough for him to re-ascend in the past to beginning of the Tertiary period. Not only in the Red of Scotland, but in the very heart of the oldest form tions known in England and Wales, there were nume evidences of previous volcanic activity. To use Cek words: "Placed on the edge of a continent and margin of a great ocean-basin, the site of Britain has along that critical border-zone where volcanic energ more active and continuous."

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The chief outlines of that marvellous story, which shardly suspected some years ago, were recently the in Geikie's presidential addresses to the Geologica ciety of London; a work which has been qualified by Iddings, the distinguished American petrographer one of the most important contributions to the bi of volcanic action." Nevertheless, it is only a preli paper, and in the same manner as he already has det a special memoir to the volcanic outbursts of Te times, Sir Archibald promises to publish in a short a detailed account of the Palæozoic eruptions.

In order to become competent for such an taking, the author had prepared himself without sp time, labour, or trouble. Having travelled over of Europe, from the north of Norway to the L Islands, he was anxious to learn from personal obse tion the broad features of that American continent geological construction of which seems to have conceived on a much larger scale than that of E Therefore in 1878 he rambled over many hundred miles in Western America, from the Archæan tel Canada to the huge volcanic plateaux of Orego

laho, where a country as large as France and Great ritain combined has been flooded with a continuous eet of basalt. But stratigraphical studies were only art of the necessary initiation. Sir Archibald had been ne of the first field-geologists in England to perceive De importance of microscopic investigation as an djunct to field work. He might well have left the care f that special study to some officer in the Survey; but e wished to make himself master of the subject, Conected by personal friendship with Zirkel, Renard, and ther eminent petrographers, he gave to that branch of he Survey such a vigorous impulse, that upwards of 5000 slices of British rocks were soon prepared and lassed in the collections of the museum in Jermyn Street; and if he can now rely with full confidence on his distinguished professional officer, Mr. Harris Teall, for any determination of rocks, he himself has won all mecessary competence in that department of science, which has been so much enlarged during the last twenty years. An undertaking so ably provided for could not but prove successful. It is not, of course, our purpose to give an account of the results arrived at. The "History of Volcanic Action in the Area of the British Isles," as it was presented in the presidential addresses for the years 1891 and 1892, is so much condensed that it must be read in extenso by every one who takes interest in the matter. We would only call attention to the final summary, where some important and far-reaching conclusions are deduced from the observed facts. One of them is that British volcanoes have been active in sinking rather than in rising areas; to which it is added that the earlier eruptions of each period were generally more basic, while the later intrusions were more acid.

When presenting "a connected narrative of ascertained knowledge regarding the successive epochs of volcanic energy in this country," Sir Archibald did more than write an important chapter of British geology. It may be said that he definitively settled the long-controverted question, whether there has been any essential difference or not between the di-play of volcanic activity at various geological periods. Not very long ago some scientific schools-above all, on the Continent-showed the greatest reluctance to admit that true volcanoes could have existed during the Palæozoic era. When they were told of Cambrian lavas and felspathic ashes, of Silurian tuffs, especially of Precambrian felsites, they could not restrain a strong feeling of incredulity. Against old granitic or porphyritic eruptions they had nothing to object; but the volcanic facies appeared to them a privilege restricted to recent geological times. To this the present writer might bear personal testimony, as he found his "way of Damas" only when he was fortunate enough to ramble over North Wales, and gather with his own hands pieces of vesicular lava embedded in the tuffs of the Snowdon, or boulders of true felsite lying at the base of the Cambrian series at Llanberis.

Not only has Sir Archibald, in common with his countrymen, always escaped that kind of misconception, but he will have contributed more effectively than any other to place the matter in the true light. Thanks to the cliffs of Scotland, he has been able to trace the roots of old volcanoes, to show true volcanic bombs entombed in

sediments, and to mark the site round which vast piles of lavas and tuffs, 5000 or 6000 feet in thickness, had been heaped up. Likewise, in his previous paper on Tertiary volcanoes, he had established by indisputable sketches that the granitic rocks of the islands of Mull and Skye were ejected during the earlier part of the Tertiary period, and that they belong to the central mass of intrusions, the lateral veins of which have taken the form of granophyres.

There is another kind of useful geological work which Sir Archibald has a right to be credited with; we allude to the restoration of the most friendly relations between the official Survey and the Geological Society of London. For many years those relations had been maintained at a rather low temperature; both independent geologists and Government's surveyors showed, as it were, more inclination to mutual and severe criticism than to brotherly co-operation. This period of misunderstanding is now well over. Thanks to the present Director, the Geological Society has more than once received the early flower of the capital results obtained by the Survey, and the recent Presidentship of Sir Archibald has solemnly sanctioned the return of a harmony which will prove of great benefit to the advancement of geological science in England.

This is a very brief and imperfect account of the chief work accomplished by the field-geologist, a work which would have been sufficient for the whole of a man's life. But we have now to consider in Sir Archibald the master who has been engaged in important educational duties. When he was appointed in 1871 to the chair of Geology at Edinburgh he had the whole work of that department to organize, a task which may be wearisome, but which involves great benefit for a man of labour, as he must face every difficulty, and obtain day by day a clear and personal idea of all that is required for teaching. To that we are indebted for the undisputed superiority which Sir Archibald has displayed in his "Text-book," as well as in his other educational writings, such as the ClassBook," a very model of clearness, whereby it has been once more demonstrated that those only are qualified for writing elementary books, who are in the fullest possession of the whole matter. Likewise he is the author of small books or "primers" on physical geology and geography, of which some hundreds of thousands of copies have been sold, and which have been translated into most European languages as well as into some Asiatic tongues. This exceptional success will be easily understood if we remember that in Sir Archibald's works the traditional barrenness of geology is always smoothed and adorned by a deep and intense feeling for nature. Nobody has done more than he to associate geological science with the appreciation of scenery. In numberless writings he has undertaken to explain the origin of existing topographical features. Among others reference may be made to the volume on "The Scenery of Scotland viewed in connection with its Physical Geology," first published in 1869, of which a new edition appeared in 1887; also to Geographical Evolution," in the Proceedings of the Royal Geographical Society for 1879; and "On the Origin of the Scenery of the British Isles," published in NATURE (vol. xxix. pp. 347, 396, 419, 442).

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Ve need not waste time in considering whether some ans could not be found to continue to take astronoal photographs of say an hour's exposure, or to use mical balances of the greatest delicacy, with a railway tramway of any kind running intermittently within nty yards of the laboratory in which the work is suped to be carried on; and it is also clear that the result ld be disastrous if the traffic were carried on at any cticable depth.

ast year a joint Committee of the Houses of Lords Commons fully considered the question as to the ciples on which future extensions of what may be ed omnibus traffic should be carried on, and they e to the conclusion that electric and cable railways structed at a considerable depth below the surface ld probably be the most convenient means for ing the various parts of the metropolis more closely. ome people have attempted to read into this part of Committee's report that given a cable or electric way there will be no shaking! And it has been sugted that all such opposition as we have expressed ve should disappear. This of course is the view of the pany-promoter, but it will commend itself to no one In fact there are special objections to an electric vay in addition to those earthquakes more or less gated which are associated with any system of tion.

o evidence was laid before the Committee as to e of the disadvantages which are incidental to the of electricity. It is true that these disadvantages not such as to interfere with the further extension lectrical railways, but they are of sufficient importto be considered in deciding on the routes which railways shall follow. Experiments made some little ago in the neighbourhood of the South London ctrical Railway proved that the electrical disturbances so great that it was doubtful whether ordinary er students' work could be carried on within a rter of a mile.

quarter of a mile! And the proposed railway, or tric way, or cable way, or tramway is to run within ty yards of electrical and magnetic laboratories. 'en n'est sacré pour un sapeur !" an evil hidden in the und ceases to be one.

must not be forgotten that the interests at stake are only those of the higher sciences and research. It t, perhaps, be argued that as the instruments used nvestigation become more sensitive, and as the necesfor accuracy increases, it may be necessary that irches of a special character should be carried out in es specially selected for their freedom from all rnal disturbance. A serious damage will, however, be to our large towns if it becomes necessary for every le-class youth who wants to master more than the ents of science to become a boarder at a country ge. It is frequently complained that there is an asing separation between class and class, those who ble to do so leaving the towns for the more distant bs. It would be a thousand pities if the higher ition were also, even in part, to be banished from our centres of population.

may be urged by the promoters of the company that I be easy for them or the Government to plant the

Royal College of Science elsewhere, but if the buildings of the College are notoriously inadequate, it was clearly stated at the time when the proposal to place a collection of pictures on the site reserved for science made it necessary to explain the future policy of the Department of Science and Art, that the collections and the laboratories attached to them were in the future to be housed on the plot close to the present site.

But as stated before, it is not necessary only to base our case upon the injury which would certainly be done to the Royal College of Science; it must be remembered that hard by is the City and Guilds Central Institution, in which extensive and costly laboratories, built by the munificence of the City Companies, have during the last few years been filled with students, many of whom are engaged in advanced studies.

Every argument which applies to the one case holds good in the other. The work of the City Companies and the interests of these institutions are endangered in the same way, and for the same reasons, as those of the Government College over the way.

On the previous occasion, when it was proposed to bring a railway at the back of the Central Institution, the Professors there, with the sanction of the City and Guilds of London Institute, opposed the scheme. We understand that the Professors have again made a representation to the Institute which in all probability will result in steps being taken to prevent the construction of any railway or tramway which would interfere with the work carried out in the Physical Department of the Central Institution.

In both these institutions it is as important that the apparatus should be used without let or hindrance from external disturbances, as say, that the reading-room in the British Museum should not be rendered uninhabitable by a nuisance produced either by private individuals or by some company in the neighbourhood.

On these grounds we protest in the name of science against a railway of any kind in Exhibition Road.

If there is one district in the metropolis which ought to be thus secured, it is the neighbourhood of the great national scientific school and its associated collections.

And here a word about these Science Collections. There are philistines among us who think that the collections would do very well without the schools, as the schools could do very well without either higher teach ing or research.

There is no doubt a certain advantage to be gained by collecting types of all sorts of apparatus, exhibiting them appropriately labelled in glass cases, through which the public may gaze with, it is to be feared, somewhat indiscriminate admiration; but it must always be recollected that the nation is proud of the British Museum and Art Galleries, not merely because they play a useful part in educating the crowds who visit them, but also because they are centres to which students resort from all parts, not only of the United Kingdom, but of the civilized world, not to gaze at the collections but to use them. In like manner a national collection of scientific apparatus should be brought together, not merely to be stared at, but to be used. By an arrangement more logical than those to which our haphazard English

customs too frequently lead, this second object is at present attained.

It is almost ludicrous that at the very moment when a Royal Commission is sitting to determine the constitution of a new University for London, Parliament should be asked to sanction a Bill which, if it serves as a precedent, may make the teaching of some of the most important sciences impossible within the metropolitan area. Indeed, in this danger we find a new confirmation of the importance of the policy which we have often urged upon those who are directly interested in the constitution of the future University.

Science teaching in Exhibition Road is threatened to-day. It may be threatened somewhere else to-morrow. It will be impossible for a number of competing colleges to defeat the railway engineers, or to preserve intact for scientific research a number of buildings planted upon sites selected without reference to the new danger which has arisen. They will be at tacked in detail, and beaten one by one. How immensely in this, as in many other matters, would their position be strengthened if they were able to speak with one voice in support of a plan decided on in common, and defended together. If the hoped-for University of the future already existed; if it s poke with the prestige of the existing University of London, combined with that of the consolidated teaching staffs of the London Colleges; if the support of a Government Department could be asked to aid a University which, like the British Museum, commanded universal respect and support; then it might be possible to obtain a ready hearing for opinions given with all the weight of a great institution of which the country would be justly proud. Till the union is effected, which alone will make science in London able to meet its enemies in the gate, we must struggle as best we can to prevent irreparable mischief.

We can only hope that the Vice-President of the Council, who is known to have the interests of the higher education at heart, will not allow a railway, electrical or other, to injure the teaching institutions clustered round the magnificent collections of apparatus in his charge.

SOUND AND MUSIC.

Sound and Music. By the Rev. J. A. Zahm, C.S.C., Professor of Physics in the University of Notre Dame. Large octavo, 452 pages. (Chicago: A. C. McClurg and Company, 1892.)

TH

HIS handsomely got-up and lavishly illustrated volume is, the author informs us, a largely expanded transcript of a course of lectures delivered by him, in 1891 "in the Catholic University of America, at Washington, D.C." Its "main purpose is to give musicians and general readers an exact knowledge, based on experiment, of the principles of acoustics, and to present at the same time a brief exposition of the physical basis of musical harmony." A clear intimation is given at the outset (p. 18) of the predominant rôle which experiment is to play in the acoustical portion of the undertaking. Had Prof. Zahm not had at his disposal "all the more delicate and important instruments" of research and verification, in the

theory of sound, constructed by Dr. Koenig of h he would "not have attempted to give the presen: tures on sound" before such an audience as that actually attended them. With Dr. Koenig's appr around him, however, he had assured means of "e taining" his hearers, and of "illustrating in a wa would otherwise be impossible the most salient facti phenomena of sound." The late Isaac Todhunte deprecated the systematic repetition of perfectly blished experiments, on the ground that their re ought to be believed on the statements of a tutorbably a clergyman of mature knowledge, recogn ability, and blameless character "-to suspect r was in itself irrational.1 Prof. Zahm's p pushes to a great length a view directly opposed to enunciated with obvious humorous exaggeratio the well-known Cambridge private tutor. Not content a single experiment decisive of each successive issue sented, he performs a whole series bringing into 2: all the resources of his superbly found collect :: acoustical apparatus. It is no detraction from the and interesting manner in which these formidably ous experiments are set forth, to say that the am space necessarily devoted to explaining the mech of the apparatus used gives to parts of Prof. Zar volume somewhat of the look of an acoustical instrace maker's illustrated catalogue. Subject, however, to defect, if defect it be, the lectures are decidedly pleasa and attractive reading. The illustrations, too. 2 thoroughly clear and beautifully executed, so tha author may be fairly congratulated on succes 'entertaining' the word is his own-his be and readers. His object, to give to general res 'exact knowledge" of the principles of acous has also been in a fair measure attained, but s to certain not inconsiderable deductions. I scribing the processes and results of experiment Zahm is clear and thoroughgoing: in expounding parts of acoustical theory which must be mast if the facts thus obtained are to be understood mutual relations, he is often vague and superficial the nature of wave-motion, the formation of stati undulations, the composition of small vibratory ments-matters of crucial importance to any conne comprehension of Acoustics-receive from himno ee elucidation. Nay, he is even chargeable with hav the misuse of a technical term of perfectly settled ing, written in a way likely to confuse his readers on these very matters. On p. 46 he calls certain p in a series of progressive waves "NODAL points there is no motion," thus confusing two things ought to be most carefully distinguished from each a point of momentary rest in a progressive wave, 23: of permanent rest in a stationary undulation. usage which restricts 'node' to this latter meaning well established that such use of it as the above is inexcusable, especially in an author who himse where, p. 146 &c., employs it in its ordinary signifa The same indifference to accuracy of expression in this volume with a frequency not creditable professor of an exact science. Thus on p. 5 return movement of a prong of a tuning fork

an

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1 "The Conflict of Studies," p. 17.