it is natural that the first question a student asks about a new book on physiology should be, "Is it the book for the College?" or the M.B., or whatever may be the examination most in vogue at his school. And this question is typical of the effect of examinations for evil, of their tendency to make men read exclusively up (or down) to the requirements of the examiners, disregarding the fact that the elementary physiology and anatomy they learn are to furnish their only weapons with which to attack the, for them, far weightier problems of pathology and treatment in their medical and surgical aspects.

On the other hand, it is a consolation to think that a good text-book must extend its beneficial influence to examinations as well as examinees, and thus improve the physiological teaching, not only by providing a trustworthy book of reference for the students, but also by putting a stop to cramming for examinations, which now forms so large a part of the teaching at London schools; for so surely as examinations improve will cramming assimilate itself to the proper teaching, and so become a work of supererogation.

I may say at the outset that Dr. Waller's book falls into the latter category, and is really the best recent work in the English language on human physiology. It presents a complete elementary account of the present state of the science, and is especially distinguished from the text-book most in vogue at the present time by its objectivity.

Without loading his text with references and names, Waller retains personal interest in his work, and quotes original experiments sufficiently to attract the attention of the reader, and to give him (so far as is possible in a text-book), a real knowledge of the subject, and opportunity to discriminate between the diverse views with which the science is burdened.

I mean, no reader is compelled to accept the facts he learns here on the ipse dixit of the author. The facts are presented plainly enough, and their significance discussed, but the student can, if he has the habit of thought, weigh the evidence for himself, and perhaps come to a different conclusion from the author.

If we may be allowed to alter the context of a sentence of the preface, giving references and original experiments is useful "because it helps to correct that credulous bias or primitive suggestibility' which is a physiological property of the human brain, and only too apt to be fostered by unmitigated bookwork.”

Dr. Waller follows the time-honoured division of the subject into vegetative and animal physiology; the latter, which includes the nervous system and its instruments, occupying half the entire work (270 pages).

Some might consider this too much space to be devoted to this part of the subject in a book intended primarily for, and certain to be used chiefly by, medical students. But one must consider that no other department of physiology can be so immediately applied to clinical work as that treating of the nervous system. In fact, a third year's man, who has learnt this well, requires merely a little book knowledge to recognize the most recondite forms of nervous disease, which would hopelessly elude the diagnostic powers of many an older practitioner, less versed in the latest advancements of neurological science.

In the eye wards, too, an exact knowledge of the

working of the normal eye is absolutely essential, and one often hears oculists complain that they have to teach students the physiology of the normal eye before they can start on their own proper subject ; and this is partly owing to the fact that these subjects are perhaps the hardest part of physiology, and partly because the student comes to them at the end of the session, and is tempted to treat them as coming last also in importance. This, however, he will be unable to do if he takes the work before us for his text-book.

The second part is treated evidently con amore, and is an excellent account of this branch of physiology. The introductory chapter on "The General Plan of the Nervous System" (which occupies only ten pages) is especially to be commended for its lucid brevity, the outcome of a masterly grasp of the subject.

This chapter is followed in order by the physiology (1) of the peripheral organs, muscle and nerve; (2) of the sense-organs, eye, ear, &c. ; (3) of the central organs, spinal cord, spinal bulb, and brain.

The section on muscle is prefaced with a short account of the chief instruments used in electrical experiments on muscle and nerve, and of Ohm's law.

The fulness with which nervous physiology is treated will make the work very acceptable to general readers, and especially to those who wish to acquire a physiological standpoint from which to attack the problems of psychology.

The first part of the work-"The Phenomena of Nutrition "treats adequately of the subjects of the blood and circulation, respiration, nutrition, excretion, and animal heat, but does not quite reach the high standard of excellence of the second part.

In a second edition one would like to see the questions of coagulation and of the origin of urea treated a little more fully and precisely. Its value, too, as a textbook would be much improved if the headings at the beginning of each chapter were also incorporated in the text, or put at the side of the page so as to arrest the reader's attention.

The whole work shows evidence of careful revision, and is marvellously free from mistakes or printers' errors. On p. 103, in describing the effect of the interrupted current on the ventricle, it should be mentioned that the frog's ventricle is meant, and not the mammalian. In conclusion, I may mention that the work is furnished with a useful bibliography (confessedly incomplete) and a good index. E. H. STARLING.

OUR BOOK SHELF. Bulletin of the New York Mathematical Society. Vol. I. Nos. 2, 3. (New York: 1891, November, December.) No. 2 opens with an article by Truman H. Safford founded upon three volumes of the "Catalog der Astronomischen Gesellschaft" (vols. iii., iv., xxiv., Leipzig, 1890), in which a sketch of the modes of observation since Bradley's time is given, and the excellence of the plan formulated by Argelander upheld. Prof. M. Merriman discusses the problem in least squares,-" to determine, by the method of least squares, the most probable values of a and b in the formula y = ax + b when the observed values of both y and x are liable to error." An account is then given of a new Italian mathematical journal (Rivista di Matematica), edited by G. Peano, the cha

racter of which is said to be somewhat similar to that of the Bulletin. Reviews follow of a work on the "Photochronograph (Hagen and Fargis, of the Georgetown College Observatory), and of Dr. Craig's "Treatise on Linear Differential Equations, vol. i. (by J. C. Fields). Besides there is a note on "Nomenclature of Mechanics" (our readers are familiar with the discussion raised by Prof. Greenhill, anent the same matter, the equation W=Mg). The "Notes" (in both numbers) give information respecting the Society and its doings. One property of numbers, out of many given, we give here—

4 + 5 + 6 + 7o + 9o + 115

=

125.

In No. 3 Dr. Fiske prints a résumé of a lecture, before the Society, "On the Doubly Infinite Products," which bristles with references to papers on the subject. Prof. Hathaway then, in a very interesting note on the "Early History of the Potential," sums up, in correction of an error that occurs in Todhunter's "History of the Theories of Attraction" (vol. ii. § 789, 1007, and 1138), "the evidence in favour of assigning to Lagrange" (as against Laplace) "the honour of the introduction of the potential into dynamics." Mr. J. E. Davies contributes a favourable review of Preston's "The Theory of Light."

To each number is appended a long list of new publications. This Bulletin, it will be seen, breaks new ground, and presents several points of interest to mathematicians. Guide to the Examinations in Chemistry. By W. Jerome Harrison, F.G S. Pp. 56. (London: Blackie and

Son.)

THE greater portion of this little book consists of answers to the questions which have been set in elementary inorganic chemistry in the examinations held by the Science and Art Department during the period 1884 to 1891. The rest of the book contains general information regarding the Department and its examinations, and also supplies hints for the successful working of the papers.

The answers are but moderately satisfactory; it may be taken that the author has frequently underrated the difficulty of expressing concisely, and at the same time clearly, the meaning which he wishes to convey. The following extracts may be taken as instances:-"Gunpowder. depends for its energy upon the suddenness with which the nitre parts with its oxygen." "The terminations -ide, -ite, and ate are given to the names of the acid-forming portions of salts."

"Nitrous water [oxide ?] dissolves in water equally, and as a whole. Air dissolves unequally in water, the oxygen being more soluble than the nitrogen."

The book is intended to be a companion to Sexton's Chemistry, Theoretical and Practical."

Manipulation of the Microscope By Edward Bausch. (New York: Bausch and Lomb Optical Company, 1891.)

THIS little treatise on the microscope, which is now in its second edition, is sure to find favour with workers with this instrument, as it forms a good introduction to books of a more advanced nature. The subject is not treated extensively, but just so far as to enable a beginner to know the whys and the wherefores of the various manipulations.

The first two chapters deal with the simple and compound microscopes, describing their adjustments, &c. Under "Objectives and Eye-pieces," which forms the heading of the next chaper, we find short but good de scriptions relating to achromatism, resolving power, flatness of field, magnifving power, &c. In the chapters on "Requisites for Work," "How to Work," and "Advanced Manipulation," the beginner is shown how to set up his instrument, to illuminate the field properly, to use the high-power objectives, and, among other things, receives instruction in the dry and immersion adjustable objectives.

The selection of an instrument is always an important item to be thought of, and the author here gives some good sound advice both about it and the choice of its accessories, and about the care which should be bestowed on it to keep it in the best working condition. The appendix contains some considerations in the testing of objectives.

The work is one which all beginners with the microscope should read, while many a hint might be gathered by an advanced student.

Harrow Birds. By G. E. H. Barrett-Hamilton. (Harrow Sold for the Harrow School Scientific Society by J. C. Willbee, 1892.)

THIS little volume ought to be of good service to the Harrow School Scientific Society, for whose benefit it has been prepared. The author was a member of Harrow School from 1885 to 1890, and evidently made excellent use of his opportunities for ornithological study. For facts which have not come within his own observation he has had recourse to the best authorities, and various gentlemen, whose names he gives, have contributed notes on the birds observed about Harrow during their schoollife. The district covered in the list is contained within a radius of about five miles around Harrow. The list

includes 197 species, of which 55 are partially or wholly resident, 27 are regular summer visitors, about 22 appear annually on migration or in winter, and the remaining 94 are visitors of rare or accidental occurrence. The species which breed regularly number 82.

LETTERS TO THE EDITOR. [The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertake to return, or to correspond with the writers of, rejected manuscripts intended for this or any other part of NATURE. No notice is taken of anonymous communications.]

The Theory of Solutions.

IN NATURE, vol. xlv. p. 293, appears a letter by Prof. Ostwald, in which he replies to a portion of my review of his book on solutions (NATURE, vol. xlv. p. 193).

ence

Prof. Ostwald finds his main cause for objection in my conclusion that he is a supporter of the "physical" as distinguished from the "chemical" theory of solution. To such a statement he objects on the ground that he " cannot at all admit the existof a "contrast" between the two theories; and further that he intentionally neither set up nor attempted to answer the question-Is solution a physical or a chemical process?-because he holds it to be "unclear and therefore very harmful." In the rest of the letter he concerns himself mainly with expounding what he prefers to name the "new theory "of solution, and seeks to show that between it and the hydrate theory there is no antagonism or rivalry.

The first point to consider as bearing on the question at issue is the definition of the "new theory" which may be gathered from extracts such as the following:

"The theory of solutions which I represent and defend consists" "of a certain number of laws, i.e. of exact relations between measurable quantities.'

"The presentation of laws of solutions, as known up to the present, forms the subject of my book."

But surely it cannot be admitted that a number of exact relationships constitute a theory; for theory is concerned with saying why such relationships should exist, with supplying ideas to connect them together. Now, contrary to the apparent meaning of the last quotation given above, Prof. Ostwald's book contained much of the nature of a true theory. Indeed, the ideas which seemed to determine the general treatment of the subject, and which formed the only justification for the free use made in the book of gaseous laws, were the hypothetical functions ascribed to the solvent and the dissolved substance. The hypothesis bere involved, in conformity with what has been the usual custom in this country I termed the "physical theory," and I am at a loss to see how any reasoning based on the definition of the "new theory" affects the use of this term. For the theoretical matter given in the book evidently refers

to ideas differing from those involved in the "new theory," which, so far as extracts such as the above go, appears to include nothing whatever of a theoretical nature.

Even in Prof. Ostwald's letter there are, however, indications that in his book he went beyond the mere statement of the laws of solutions. For example, he says: "In my book the question is this one of facts, and although I have therein made more use of molecular considerations than I should at present hold to be proper, yet I have done so only to render more clear the actual relations, and never to prove quantitative laws."

Now it was solely the "development of the consequences of facts"-this use, which Prof. Ostwald admits to have been excessive, of "molecular considerations "-which has generally been, and was by me, styled the "physical theory." The facts themselves no one can question; indeed, I took pains to point out in my review that the facts, as given in the book, would alone serve to make it valuable. The theoretical matter, however, called for separate consideration. It alone was, and, so far as I can see, it alone could be, designated the "physical theory." In denying the contrast between the so-called chemical and physical theories, Prof. Ostwald declares that he never maintained that no interaction takes place between the solvent and the dissolved substance." If such was his opinion when writing his book, it may be asked, Why in all fairness should he have defined solutions as homogeneous mixtures? Why did he not state clearly that interactions between solvent and dissolved substance were possible? It is quite true that, in my review, instances were given of chemical expressions used in the book, but no stress was put upon these by the author as indicating the general occurrence of chemical changes in solutions. They seemed to arise, not because of, but rather in spite of, the author's idea of the nature of solution, and could only be regarded as inconsistencies. The theme of the book was the explanation of the properties even of concentrated solutions by considering the interactions of molecules of the same kind, by treating the dissolved substance as if it were gasified. If such a method of treatment were described as physical," I think the commonly accepted meaning of the word was in no way impaired.

Indeed, much of Prof. Ostwald's book can hardly be justifed if interactions of a chemical nature are probable in solutions. For instance, several pages are devoted to the use of van der Waals's equation in dealing with solutions. To anyone familiar with the deduction of this equation, the validity of its application to a solution even when the solvent is regarded as indifferent is highly questionable. If, however, it is admitted that something of the nature of a chemical reaction may occur between solvent and dissolved substance, that the latter may not be in a pseudo-gaseous condition, then the application of the equation can hardly be termed otherwise than meaningless.

In conclusion, I can only express regret if my review has tended to create further misconception on this vexed question of solution. At the same time, I hope I have been able to indicate to Prof. Ostwald the points which led to my use of the terms to which he objects; and I venture to think that in the discrepancies which appear to exist between the ideas as given in his letter, and those which the reader has to gather from his book, is to be found sufficient reason for the use of the statements to which exception has been taken. J. W. RODGER.

London, February 1.

Arrow Poison.

LAST year a French naval surgeon, M. Ledantec, published in the Annales de l'Institut Pasteur the result of some investigations he had made into the nature of the arrow poison of the natives of the New Hebrides. Wounds from these arrows give rise, as is well known, to tetanus, and M. Ledantec was able, by the subcutaneous injection of the scraped off poison, to kill guinea-pigs under typical tetanic symptoms. He learnt from a Kanaka that they are prepared by smearing the arrow-heads (which are made of human bone) first with tree gum and then with mud from a swamp, which mud he found to contain numbers of Nicolaier's tetanus bacillus.

As far as I am aware, this has been recorded only of the natives of the New Hebrides and some of the neighbouring groups (the arrow poison of Stanley's dwarfs is certainly not the same), and I was therefore much interested some days ago by coming accidentally upon an old record which seems to show that the natives of the Cape Verd coast were accustomed, more than three hundred years ago, to get rid of their enemies in a

similar manner. In Hakluyt's "Voyager's Tales," published in 1589 (I refer to the little reprint edited in 1889 by Henry Morley), is the narrative of one Miles Phillips, in which occurs the following passage:-"Upon the 18th day of the same month (November 1567) we came to an anchor upon the coast of Africa at Cape Verde, in twelve fathoms of water, and here our General landed certain of our men, to the number of 160 or thereabouts, seeking to take some negroes. And they, going up into the country for the space of six miles, were encountered with a great number of negroes, who with their envenomed arrows did hurt a great number of our men, so that they were enforced to retire to the ships, in which contest they recovered but a few negroes; and of these our men which were hurt with their envenomed arrows, there died to the number of seven or eight in a very strange manner, with their mouths shut, so that we were forced to put sticks and other things into their mouths to keep them open." In the language of modern medicine, they succumbed to tetanus traumaticus. The voyagers left the coast soon after, and there is no further mention of the natives or of the wounded.

There is, of course, no proof that the arrows were poisoned with mud or earth, but the probability is considerable. The chief interest lies in the age of the record, which forms in some manner a pendent to the researches of M. Bossano (Comptes rendus, 1888), which showed the tetanus bacillus to have a very wide distribution in space.

It is a curious consideration that this and the other famous arrow poison, curare, both kill by their action on the voluntary muscles, the action of one being diametrically opposed to that of the other. A. COPPEN JONES.

Davos Platz, Switzerland, January 30.

The Implications of Science.

HITHERTO prevented from again writing, I cannot now remair passive and allow Mr. Dixon to escape from bis irrational position under cover of a cloud of verbiage-like a cuttle-fish through water made turbid by its ink.

In my lecture I pointed out that certain truths are implied in all physical science. They are so implied. If Mr. Dixon thinks they are not, it is for him to show how experimental science could be carried on, with any real, serious doubt about them. This he has certainly not yet done.

Our knowledge of our own existence "in the present," is knowledge of a particular concrete fact, not of an abstract necessary truth. That "whatever feels, simultaneously exists," is such a "necessary truth," but it is an abuse of language to apply that term to anything which may cease to exist the moment after its existence is recognized.

That " nothing can simultaneously be existent and nonexistent," does not at all depend upon "terms or "definitions," but is a law of " things.' It would not lose its validity and objective truth, not only if there were no such things as "terms" and "definitions"; it would not lose it if the whole human race came to an end.

I am glad to find my critic does "not doubt" that if he lost an eye his condition would thereby be modified, but if he does not also see that this applies and must apply everywhere and everywhen, I do not envy him his power of mental vision. Oriental Club, February 2. ST. GEORGE MIVART.

The New Forest in Danger.

IN connection with my letter which appeared in NATURE of the 28th ult. (p. 295), it may interest some of your readers to know that the petitions, to which I referred, in support of the Bill for excepting the New Forest from the operation of the Ranges Act, 1891, have already been signed by Lord Walsingham, F. R.S. Prof. C. Stewart (President of the Linnean Society), Sir Joseph D. Hooker, F.R.S., Dr. P. L. Sclater, F.R.S., Mr. Osbert Salvin, F. R.S., Dr. A. Günther, F.R.S., Dr. H. Woodward, F.R.S., Mr. W. Carruthers, F.R.S., Dr. D. Sharp, F.R. S., Mr. Thiselton-Dyer, C.M.G., F. R.S., Mr. H. W. Bates, F.R.S., Mr. F. DuCane-Godman, F. R.S., Dr. G. Buchanan, F.R.S., Dr. B. Richardson, F.R.S., Prof. J. O. Westwood (Professor of Zoology, Oxford), Dr. Thorne-Thorne, F. R. S., Mr. J. G. Baker, F. R.S., Mr. W. H. Preece, F.R.S., Mr. Botting Hemsley, F. R. S., Mr. E. B. Poulton, F.R.S., Mr. R. McLachlan, F.R.S., Mr. C. B. Clarke, F.R.S., Major-General Carden, Prof. Jeffrey Bell (Secretary of the Microscopical

Society), Dr. Franklin Parsons, Mr. Daydon Jackson (Secretary of the Linnean Society), Mr. J. E. Harting, Dr. Bowdler Sharpe, Mr. J. Britten, Mr. E. Saunders, Colonel Swinhoe, Mr. A. W. Bennett (Vice-President of the Linnean Society), Mr. Percy Sladen (Secretary of the Linnean Society), Mr. D. Morris, Mr. Miller-Christy, and by a large number of other Fellows of the Linnean, Geological, Zoological, and Entomological Societies of London; and by the editors of the Geological Magazine, the Journal of Botany, the Zoologist, the Entomologists' Monthly Magazine, and the Entomologist. HERBERT Goss.

Linnean Society, Burlington House, W., February 6.

WE

ON THE NEW STAR IN AURIGA.

E were enabled last week to make an announcement of the discovery of a new star in the constellation Auriga, as we received on Wednesday the Edinburgh Circular giving an account of the manner in which the first information had been received. A telegram was sent by Dr. Copeland to the Astronomer-Royal on the date of the reception of the post card-Monday, February 1—and, as we have since learnt from the Astronomische Nachrichten, a telegram was also sent by Dr. Copeland and the Astronomer-Royal to Kiel. Unfortunately there is at present in England no local system for the distribution of astronomical intelligence of this character, so that it will probably be found that the fine night of Monday was only devoted to observations of the new star in a very restricted number of Observatories. The necessity for correcting this state of things has been pointed out by Mr. Lockyer in the Times of Friday, and it is to be hoped that some steps may be taken to rectify the defect. As it turns out, however, no very great harm has been done, for the new star, instead of degrading its light rapidly from the day of its discovery on February 1, seems if anything to have brightened, so that the changes in its light between Monday and Wednesday were probably not so great as those observed in Nova Cygni during the first two or three days of its visibility.

A telegram from Prof. Pickering communicated by the Astronomer-Royal to the Times of Monday seems to show that the star, instead of bursting forth suddenly about the date when the anonymous post-card was sent to Dr. Copeland, has really been visible since last December, perhaps even for a longer time; but in any case it has not been registered in any recognized Catalogue. Prof. Pickering states that he finds this star visible on three plates belonging to the series of the Draper photographs at different dates during the month of December. The telegram through the "Centralstelle für Astronomische Telegramme," Kiel, runs as follows:-"Copeland's Nova bright on photograph December 10, faint December 1; maximum December 20; spectrum unique. -PICKERING." It would thus appear that Prof. Pickering had photographed the new star on the three dates named in the course of the photographic mapping of stars and their spectra which he is carrying out at Harvard College Observatory. We do not yet know whether the plates were examined at the date on which they were taken, or whether the telegrams relating to the appearance of the Nova may have caused an examination to be made, but the spectrum was visible on all three plates.

As we stated last week, the observations in England, commenced on Monday night at Edinburgh, on which date Dr. Copeland saw bright lines, and at the Royal Observatory on the same evening, when the new photographic 13-inch refractor was used for determining the exact position of the star. With this fine instrument the Astronomer-Royal was able to detect that the star differed from the other stars on the plate in appearance.

As to the work on Tuesday night, at present we know nothing. An announcement of the discovery appeared in the Times of Wednesday, on which date also, as we have already stated, Dr. Copeland's Edinburgh Circular

was received in London. On that night, therefore, which happened to be fine, observations were commenced at South Kensington, and two photographs were obtained, together with some eye-observations, which were communicated to the Royal Society by Mr. Norman Lockyer on the next day in a preliminary note, from which we make the following extracts :

"Last night was fortunately fine, and two photographs were taken of the spectrum-the first exposed from 7.30 to 9, or for 1h. 30m.; the second exposed from 9.30 to 12.30, or for 3h. cm. The first registered 13 lines; the second appears to contain some additional ones, but they are very faint, and have not yet been measured. A complete discussion of these photographs will form the substance of a subsequent communication, but already the following approximations to the wave-lengths have been obtained, the photographs being treated absolutely

66

independently, means, however, being taken for the four

least refrangible lines, as there has not yet been time to construct a proper curve for this region :

"I have recently taken up the question of stellar spectra. and find that a 6-inch object-glass with a prism in front of it is all that is required for the brighter stars. This instrument was employed upon the Nova, which is of about the fifth magnitude, so the exposures were necessarily long.

"For the eye-observations, the new 3-foot mirror which has recently been presented to the Astro-Physical Laboratory by Mr. Common was employed, but unfortunately the clock is not yet mounted, so that the observations were very difficult.

"C was the brightest line observed. In the green there were several lines, the brightest of which was in all probability F, the position being estimated by comparison with the flame of a wax taper. Another line was coincident—with the dispersion employed-with the radiation at wave-length 500 from burning magnesium wire. A fainter line between the two last-named was probably near 495, thus completing the trio of lines which is characteristic of the spectra of nebulæ. There was also a fairly bright line or band coincident with the edge of the carbon fluting at A 517 given by the flame of the taper. A feeble line in the yellow was coincident under the conditions employed with the sodium line at D.

"The hydrogen line at G was distinctly seen, as well as a band, or group of lines, between G and F.

"Nearly all the lines appear to be approximately, if not actually, coincident with lines seen in the various types of Cygnus stars, the chief difference being the apparent existence of carbon, hydrocarbon, and calcium in the Nova.

"The colour was estimated by Mr. Fowler as reddishyellow, and by Mr. Baxandall as rather purplish. My own impression was that the star was reddish, with a purple tinge. This was in the 10-inch achromatic. In the 3-foot reflector it was certainly less red than many star of Group II. No nebulosity was observed either in the 3-foot or the 10-inch refractor, nor does any appear in a photograph of the region taken by a 3-inch Dallmeyer lens with three hours' exposure. It should be stated that the camera was carried by the photographic telescope, the clock of which had had its normal rate purposely changed to give breadth to the spectrum. "The photographs were taken and reduced by Messrs. Fowler and Baxandall. The eye-observations and comparisons were made by Mr. Fowler."

The nights of Thursday, Friday, and Saturday were hopelessly bad, but on Sunday night the weather cleared, and more photographs were taken at South Kensington, an account of which, we believe, has been communicated to the Royal Society. Observations of the Nova are therefore well in hand, and there is no doubt that a comparison of the photographic plates obtained in December and February will provide us with much minute information regarding the behaviour of our new visitor.

The remark in Mr. Lockyer's communication to the Royal Society, that the spectrum of the star contained nearly all the lines visible in the stars in Cygnus, is one of considerable interest and importance, because, if it be confirmed by subsequent observations, it will show that these stars in Cygnus cannot be stars in the true sensethat is, bodies like our sun. This seems pretty evident from the fact that their spectroscopic phenomena can be reproduced by another body which suddenly appears, and probably will rapidly become invisible. The idea that any of these bodies are "worlds on fire," as was once thought, need now no longer be discussed.

MR. TESLA'S LECTURES ON ALTERNATE CURRENTS OF HIGH POTENTIAL AND FREQUENCY.

IT is not often that the outward and visible signs of a great scientific success are so prominent as they were last week at the Royal Institution. The reports which have reached this country of the work of Mr. Nikola Tesla have made his name known to those who are watching or aiding the progress of electrical science. He was recently invited by the Institute of Electrical Engineers to lecture before it, and the interest which his coming excited spread in widening circles as the day on which he was to exhibit his experiments drew near.

It was evident that the ordinary meeting-room of the Institute would be too small, and the Managers of the Royal Institution placed their theatre at its disposal. Members of the Royal Institution, were, however, anxious to hear and see for themselves; and finally Mr. Tesla consented to lecture on two consecutive nights to the Institute and the Institution respectively.

On both occasions the room was full; on the first it was overflowing. Gathered round the lecture table was a crowd of those whose business it is, either as theorists or as practical men, to keep abreast of the wave of scientific advance; but as the youthful lecturer -who looks even younger than his years-with a modesty and charm of manner which were altogether irresistible, showed wonder after wonder, the interest of this critical audience deepened into enthusiasm. The speaker's broken English and imperfect explanations did not detract from his success. His marvellous skill as an experimentalist was evident and unmistakable, and his hearers left the room convinced, not only that another step forward has been taken, but also that in

Mr. Tesla we have a scientific explorer, who, if health and life be granted him, will travel fast and far. Briefly, Mr. Tesla has done much to attain the continuous stream of electrical oscillations which Prof. Fitzgerald, at a recent meeting of the Physical Society, compared to a continuous whistle. The oscillations which Hertz studied die out almost instantaneously. Could they be maintained, a practically new weapon would be placed in our hands. Tesla does not, indeed, maintain them, but he renews them many times per second, and the results are marvellous.

Though the potential is enormous, the electrode of the apparatus can be safely handled. If a person in conducting communication with it touches a vacuum bulb or tube it glows, and if the tube is brought near to others it sets them a-glowing too. No return is needed, the current is completed through surrounding space. The phosphorescent materials in some of the beautiful tubes lent by Mr. Crookes shone brightly when one electrode only was connected with the coil. If the terminal is surrounded by an aluminium tube, the glow is notably increased. The experiment of making a vacuum-tube luminous by simply holding it in an oscillating field was successfully performed, and the lecturer himself received with impunity a crackling discharge, some six or eight inches in length, by holding his hand at that distance from the terminal of his coil.

All these things are not merely wonders. Mr. Tesla is working with an object. He is one of those who hold that a phosphorescent glow is the light of the future. He hints at artificial aurore spreading from the summits of towers of hitherto undreamt-of height, and he has at all events got as far as producing in air at atmospheric pressure a glowing plane bounded by two rings about a foot and thirty inches in diameter respectively. Whether his visions will all be realized may be doubtful. There is is no doubt that they are guiding him aright. As Lord Rayleigh said in moving the vote of thanks, a door has been opened into a new region of inquiry, into which Mr. Crookes and Mr. Tesla have entered almost alone.

Those who some fifteen months ago heard Prof. Hertz acknowledge in terms of genuine emotion that he had built upon a foundation laid by Englishmen, that Englishmen had first recognized the importance of his work, and that from England its first reward had come, must have listened with pleasure when the part that this country has taken in the development of electrical science was referred to in a like appreciative tone by Mr. Tesla. It is not indeed that the achievements of our great electricians are bettered or rendered more important by acknowledgment, but it is pleasant to note how cosmopolitan science is becoming, and that among scientific workers the feeling of fellowship is overcoming that of rivalry. For the rest we can only congratulate Mr. Tesla alike upon his work and his reception, and the scientific world on the exhibition of a number of beautiful experiments which will afford food for useful reflection to theorist and experimenter alike.

A. W. R.

The announcement of Mr. Nikola Tesla's lecture to the Institution of Electrical Engineers excited widespread interest among all in the least degree interested in electrical science. The succession of almost marvellous experiments in which in great measure it consisted must have gone far beyond the anticipations of the most sanguine of those of the audience who had had no previous account of the nature and results of his work. It is not too much to say that the Royal Institution lectures mark a distinct epoch in the progress of theoretical and applied electricity. While, on the one hand, the experiments which the lecturer showed seemed to point to a possible revolution of our methods of electric lighting, on the other hand they must have suggested, if not for the first