At the same time, it must be remembered that the whole work is one written for the student, and from this point of view it may be maintained that the logical arrangement is to be preferred. The usefulness of such an extended general treatise on physics is, however, far from being limited to the purposes of a university course, and the convenience of the older student who needs his theory for its application to practice might well have received more consideration.

It is to be remarked also that Prof. Bouasse's "Cours de Physique" is essentially a treatise on mathematical physics. The author takes a keen interest in the most recent developments in physical science from the theoretical point of view, but it is not to him that we should turn for information as to experimental work.

This premised, it may be said that the work is one which should command attention. Prof. Bouasse has the faculty of presenting his mathematics in a clear and attractive form, and his theoretical discussion of practical points often presents novelties of value to the practical experimenter.

The first chapter is devoted to the discussion of Maxwell's equations of the electromagnetic field. It is unfortunate that so much reference to vol. iii. of the work should be necessary, but, nevertheless, the matter is presented with admirable clearness, and the student has no cause to complain of the author's

dictum :

"The reader cannot spend too much time on this first chapter; if he understands it well, all the rest of the volume will appear clear to him. If he fails to understand it-nous ne saurions trop lui conseiller d'abandonner la théorie électromagnetique de la lumière."

Then follows the section of some seventy pages on Hertzian waves and their application in wireless telegraphy. The treatment is of interest; it includes an account of the general theory and a mathematical discussion of various practical questions, especially the propagation of a disturbance along a wire; but it is necessarily incomplete, and would be of more value in a volume not so specially devoted to optical theory. The main part of the work is that devoted to the discussion of double refraction and of polarised light. The theory is directly based on that of the propagation of electromagnetic waves in an anisotropic medium; from this is deduced the equation of the wave surface and the construction of Fresnel. This leads up to a sufficiently full treatment of the phenomena connected with double refraction as dealt with in any modern treatise on physical optics; as elsewhere, the mathematical presentment has many original and attractive

features.

In the succeeding chapters reflection and refraction, dispersion and absorption are fully discussed from the standpoint of the electromagnetic theory. A somewhat brief treatment of the electron theory leads to the consideration of the Zeemann effect, and the phenomena of emission, phosphorescence and fluorescence, &c., while the concluding chapter deals with the

As has been sufficiently indicated, the whole of the section of physical optics here dealt with is treated as a deduction from the equations of the electromagnetic field. This may be a simplification from the point of view of theory, but we are inclined to think that to the student it may give an air of unreality to a subject which, above all others, is based on the most complete and exact experimental data.

OUR BOOK SHELF.

On the Poison of Venomous Snakes and the Methods of preventing Death from their Bite. Reprinted papers by the late Sir Joseph Fayrer, Sir Lauder Brunton, and Major Leonard Rogers. Pp. iii+174. (London: Macmillan and Co., Ltd., 1909.) Price 2s. 6d. net.

THIS publication consists of a re-issue in book form of six papers reprinted from the Proceedings of the Royal logical action of snake venoms. They were first pubSociety. The first four papers deal with the physiolished more than thirty years ago, and then represented important advances in knowledge. They cannot, however, be expected to reflect the present-day knowledge of the action of snake venoms. The fifth paper, bemethods of destroying the activity of cobra poison, longing to the same period, deals with chemical such as by chloride of gold or of mercury. The last paper, which was published in 1904, and is the only one of the series in which the last-named author cooperated, deals with the experimental results of the treatment of snake-bite by free exposure of the wound and local application of potassium permanganate.

To be of practical service in the treatment of snakebite, any remedial measure must be rapidly available and easily applicable. To meet these conditions, one of the authors devised a special instrument consisting of a small lancet-shaped blade to expose the wound made by the serpent's bite, this blade being set in a short wooden handle, which is hollowed so as to form a receptacle for sufficient permanganate of potash. Experiments were made on rabbits and cats to test the value of the method and instrument. The results,

especially in the latter animals, were encouraging, in so much as it was found that death could be prevented from a dose of venom considerably larger than that which was sufficient to kill a control animal. At the same time, it may be pointed out that the conditions of these experiments do not represent adequately the conditions obtaining in an ordinary case of snake-bite. The efficacy of the antidotal action of far the venom can before absorption be destroyed by potassium permanganate depends solely upon how intimate contact with the permanganate. In the authors' experiments the venom was injected into the subcutaneous tissues, in which case it was relatively easy to ensure contact of the venom with the antidote. whereas in a case of snake-bite the venom is injected difficult to bring the permanganate into contact with usually into deeper tissues, when it is much more the venom. It is thus probable that these experimental results ascribe to this method of treatment a value higher than would be found to attend it in practice.

While from its simplicity and cheapness this method of treating snake-bite ought not to be lost sight of, it is by local application and general administration of probably does not represent the ideal attainment, which an antivenomous serum, and further efforts ought to be made in the direction of obtaining such serums of

high antidotal properties. If dried, an antivenomous serum retains its neutralising power for a long period, and it possesses this great advantage over a mere chemical antidote, that it can also antagonise venom which has been absorbed, and may thus be of service for a longer time after injection of the venom. Bathy-orographical Map of Africa. 1-8,400,000. Bathy-orographical Map of Asia. 1-9,300,000. (Edinburgh: W. and A. K. Johnston, Ltd.: Price 125. each.

WE must congratulate Messrs. W. and A. K. Johnston on these excellent additions to their series of orographical maps. The elevations in Africa show 10,000, 5000, 2000, and 1000 feet and below sea-level. The general effect is satisfactory, though the very deep green is, we think, somewhat unpleasing. The 10,000-feet contour shows the higher elevations of the Atlas, Abyssinia, the Lakes Plateau and the Drakensbergen, but the tint is indistinguishable by a class. It would, however, have probably made the map more useful if the 8000-feet line had been selected, as the highest points are not of great importance for an educational map except in the region of the great lakes. As it is, the mountainous areas do not indicate their special character.

The other contours selected show the formation of Africa well. The sea depths shown are 100, 1000, 2000, and 3000 fathoms. It is to be regretted that the same contours have not been chosen to represent both the land and sea, as the plateau character of Africa would have been brought out with much greater effect.

Both in Africa and Asia, physical names have been very fully shown. As they cannot be read by a class, it is a pity that they have not been printed faintly in blue, like the initial letters of towns. The mass of black lettering largely spoils the graphic character of the maps.

Actual mistakes are few, though one may be notedin the north-east of Abyssinia the area below sealevel has been coloured as more than 1000 feet.

The map of Asia is more effective than that of Africa, possibly owing to the selection of the contours. The 10,000-feet affords a means of comparison with Africa, but it should, if possible, have been printed the same depth; then the 15,000- and 20,000-feet lines would, with suitable graduation, have illustrated the character of the Tibet Plateau. At present minute and close examination is necessary to distinguish the features of the North-West Frontier. The lower elevations are much better shown. The 100, 3000, and 6000 feet bring out well the great river valleys and depressions of Asia.

In spite of these defects, the maps are likely to prove more useful for schools than any that have previously been published of these continents. Publications of the Research Defence Society. March, 1908, to March, 1909. Selected by the Committee. Pp. xv+216. (London: Macmillan and Co., Ltd., 1909.) Price 2s. 6d. net.

THE Research Defence Society was founded on January 27, 1908, "to make known the facts as to experiments on animals in this country; the immense importance to the welfare of mankind of such experiments; and the great saving of human life and health directly attributable to them." The president is the Earl of Cromer, himself a champion in the cause of kindness to animals; the committee is a strong one, its members representing all branches of science, and also including many theologians and laymen, and in March of this year the membership of the Society numbered more than 2250.

This first volume of publications contains the presi

dent's address at the inaugural meeting, a review of the Home Office Report for 1907 on, and some facts as to the administration of the Act regulating, experiments on animals, and several essays (also published separately in pamphlet form) by well-known experts dealing with the knowledge that has been derived from experiments on animals, and the saving of human life therefrom. Prof. Cushny shows that the nature of

the action and therapeutic use of all drugs of recent

introduction, and the potency of the preparations of many of the older drugs (e.g. digitalis and ergot), have been elucidated solely by experiments on animals, the value of diphtheria antitoxin and of serum treatment discussed by Dr. Courtauld and Dr. Robb respectively, in epidemic cerebro-spinal meningitis (spotted fever) is Sir David Bruce writes on the extinction of Malta fever, and Dr. Bashford's article in NATURE on recent advances in knowledge of cancer is reprinted. The evidence of Lord Justice Fletcher Moulton before the Royal Commission on Vivisection is given in extenso, and is a powerful vindication from the ethical side of the right to employ experiments on animals for the benefit of mankind.

If the standard of its publications be maintained at the level of those contained in this volume, the Society will be doing excellent work in the cause of experimental research. R. T. H.

Milk Testing. A Simple Practical Handbook for Dairy Farmers, Estate Agents, Creamery Managers, Milk Distributors, and Consumers. By C. W. Walker-Tisdale. (Northallerton: W. R. Smithson.) Price Is. net.

THE author of this little book is already favourably known by his early publications, jointly with Mr. T. R. Robinson, on butter-making and soft cheesemaking. He holds an important position in the dairy world, and, as general manager of the Wensleydale Pure Milk Society, knows at first hand all the difficulties that beset the dairyman. The result is an admirable little volume, sound in regard to analytical methods, and direct in its appeal to the man for whom it is intended. It is more than a mere collection of methods, and includes discussions of such cognate subjects as the use of preservatives. Occasionally a request is heard in certain quarters that a preservative should be allowed in milk, but our author will have none of it, and advises the dairyman to keep clear of them all, even of a certain preservative offered for sale, 66 guaranteed to contain no boron or boric acid, and claimed to be undetectable by chemical analysis"! Quite apart from considerations of the general health of the community, the author shows that the dairyman himself would suffer, since foreign milk would invariably be imported if preservatives were allowed. E. J. R.

The Journal of the Cooper Research Laboratory. Edited by Walter E. Collinge, Director. (Berkhamsted The Cooper Research Laboratory, 1909.) THE fact that the principal of a large and well-known firm like Messrs. Cooper should start a research laboratory and publish a journal is a satisfactory proof of the widespread interest now being taken in science by all who have to do with agricultural and horticultural matters. The special province of the firm-treatment of insect and fungoid pests-certainly borders more closely than usual on pure science, and no doubt a trained staff would have been wanted in any case. But here we have something more. The laboratory, we are told, "is in no sense a financial venture or business concern." Its functions are to answer inquiries from farmers, fruitgrowers, and gardeners as to preventive and remedial treatment for diseases of plants and parasitic diseases

cussed here. Mr. Johnston will find this subject admirably treated, from a theologian's point of view, in Mr. Waggett's contribution (chapter xxiv.) to "Darwin and Modern Science.

The question of the antiquity of land-plants is of great interest. Assuming, for the sake of argument, that the highly organised lycopods and fern-like plants described by Prof. Potonié as Upper Silurian ( Die Silur und die Culmflora des Harzes Geb., Abhandl. d. k. Preuss. Geolog. Landesanstalt, Heft 36, 1901) were really of that age, it would appear certain that land-plants must then have already passed through a very long course of evolution. No one is likely, in these days, to suppose that Bothrodendron and Sphenopteridium were specially created. The doctrine of mutation (of which Mr. Johnston appears to be an adherent) does not materially help in hurrying up the process of evolution, for, as Prof. de Vries himself says, Mutations do not necessarily produce greater changes than fluctuations": ("Darwin and Modern Science," p. 73).

The problem confronts us, and its solution must simply await further evidence. D. H. SCOTT. Oakley, Hants.

The Perseids of 1909.

THE weather, fortunately, took a very favourable turn on August 3, and observations have been obtained nearly every night since, though moonlight has rather seriously interfered with the work and obliterated many small meteors. Up to August 9, and including that date, the display of Perseids was decidedly poor, and quite disappointed expectation. On August 7 and 9, particularly, there appeared to be very few meteors, but the moon was shining rather strongly in the east.

On August 8 there were several brilliant Perseids observed. At 10 p.m. a fine, long-pathed meteor shot from Camelopardalus across к Draconis towards Ursæ Majoris. At 10.8 p.m. another Perseid, equal in brightness to Jupiter, passed from x to between B and Draconis. At 10.34 p.m. a third shot exactly from a Cygni to close to B Cygni. These meteors left streaks, and, in combination with a few other paths recorded on the same night, indicated a radiant at 41°+57°.

The shower will probably arrive at its most abundant phase on August 11 or 12 this year, so that the meteors already reported are merely the vanguard of the approaching main group. W. F. DENNING.

Bristol, August 10.

The Ringing of House-bells without Apparent Cause. KINDLY allow me space for a few remarks upon Sir Oliver Lodge's theory, put forth in NATURE of July 22 (p. 98), to the effect that "the bells get charged with electricity (atmospheric), and are attracted to a neighbouring wall or pipe, and then released suddenly by a spark. Now, while it is conceivable that a bell might be rung under certain conditions in this manner, during the progress of a thunderstorm or display of sheet-lightning, and granting that ordinary non-electric bells have been rung and wires fused when a house has been struck by the electric current during such storms, still, this theory is inadequate to explain those cases of mysterious bellringing on record, and for one reason, among others, that these ringings, often violent and prolonged, have been extended over a term of several weeks or months, and have constantly taken place when no storms or strong electrical conditions were apparent, and when every effort was being made to ascertain the cause.

I speak from personal experience of a case which occurred in my house when resident in the south. For a period of two months there were constant ringings-often violent, the bell lashing to and fro of the indoor bells, without apparent cause. In the case of one bell the wires were cut, but still it rang. The utmost endeavours were made to solve the mystery, but it defied all our efforts. There were no rats, the house having been made rat-proof, nor did we see one rodent during our stay. The wires were carefully traced and examined. Pendulums were affixed to all the bells to detect slight motion, and they were strongly illuminated by a powerful light and a watch

kept, sometimes all through the night. The chief offender among the bells was one communicating with a private room. The wire from this ran, high up near the ceiling, upon the varnished paper, except where it passed through a wall, which it did through a half-inch pipe. It was impossible for a rat or mouse to touch it all along its course. This bell rang repeatedly from early morn to late at night. The room was thoroughly searched and secured the shutters put up and barred and the door locked. Still the bell rang, and defied all our efforts to elucidate the mystery. On one occasion, when the whole household was together in another room, some little distance away, one of them said, "I wonder if it will ring to-night?' The words were scarcely spoken before the bell rang out, first faintly, then so violently that the bell lashed from side to side. All ran out and saw it swaying. I can state that during the whole pericd we had no thunderstorm, it being winter, and the ringings were so frequent that it would have needed scores of storms and abnormal electrical conditions to produce them, even if these had been the cause. This theory is ingenious, but one doubts whether Sir Oliver advances it seriously. Whatever is the cause of these mysterious ringings, it is patent to anyone having had experience of them, or knowing the cases on record, that it is not electricity, atmospheric or other. C. L. TWEEDALE.

Weston Vicarage, Otley, Yorks, August 6.

Variation in Relative Intensity of Helium Lines. IT has long been an open question whether the spectra of gases were subject to any general law of intensity variation such as the Wien-Paschen displacement law for incandescent solids. Reasoning from Kirchhoff's law, it is frequently assumed that the Wien-Paschen function must be an envelope to the radiation spectrum of any gas, at least for certain selected lines. Pflüger's work with the mercury lamp (Ann. Ph., July, 1908) indicated some such variation in relative intensity, but the energy (temperature) effect was obscured by the effect of varying vapour density. The latter is known to be large, so that the existence of the former was not proven.

We have recently taken up this question, using a pair of helium lamps containing very pure gas at 5 mm. pressure, and found no variation whatever when the intensity was varied by a factor of eighteen. The method was to hold one of this pair of lamps constant at a moderate current (5 milliamperes per mm.2), while the intensity of the other was varied from 0.15 to 2.70 times this value. Spectrophotometric settings were made on the brightest red line ( 668) and the bright blue line λ 447. The uncertainty in the ratios of high/low intensities was less than 2 per cent. in both red and blue; the observed difference in these ratios between red and blue was less than I per cent. The red and blue lines then increase in the same proportion over a wide range of intensity.

According to the Wien-Paschen function, an incandescent body should, for an increase in total radiation of 18 fold, increase in temperature 2.06 fold. If this increase is from 1500° to 3090°, then λ 668 would increase in that intensity, so that the blue increases 38.8 times as much range 1721 fold, and λ 447 would increase 66,850 fold in

as the red, whereas for helium we found no difference so great as I per cent. P. G. NUTTING. ORIN TUGMAN. Department of Commerce and Labour, Bureau of Standards, Washington.

Kohlrausch's "Physical Measurements."

I SHOULD like, through the medium of NATURE, to direct attention to an erratum in Kohlrausch's " Physical Measurements (third English edition, Churchill, 1894), p. 434, table 8. The value for k(s=2.0) is given as 0.458, its true value being 0-457(1). Other editions, English or German, not being at hand, I do not know whether the mistake is repeated or not. As this occurs in a very useful table in a universally used reference work, it should be of interest to a number of your readers. E. W. NELson. The Laboratory, Citadel Hill, Plymouth, August 2.

THE BRITISH EXPLOSIVES INDUSTRY.1

A VALUABLE addition to the literature on explosives has been published under the auspices of the seventh International Congress of Applied Chemistry by its explosives section, with Mr. Brayler Hodgetts as editor. It owes its inception to Mr. Oscar Guttmann, to whom the publishers pay a well-deserved

strictions on manufacture and storage, the supervision was very lax, leading to great carelessness in the manufacture and handling of such dangerous substances. Colonel Moody's report on the disastrous explosion of powder magazines on the river-bank at Erith in 1864 (from which report some startling extracts are given) fully emphasised the necessity for more stringent regulations, and led in October of

FIG. 1.-Charcoal Chambers in 1798. Back View.

tribute for his able assistance and the facilities he has afforded them by placing his unique and valuable library at their disposal.

All who have been associated with the compilation of the work are to be highly congratulated on having produced a volume which will certainly fulfil the hope expressed by Captain Tulloch in his preface, that it will"in years to come be looked upon as a work of reference connecting the past with the future," for all will agree with him, after perusing it, that "it is the only work of the kind containing so complete a history of the manufacture of explosives in this country.

It is

The book is divided into two main sections, historical and descriptive. In the former are articles devoted to each of the principal explosives, and such related subjects as percussion caps, safety fuses, and fireworks, contributed by writers specially competent to deal with each.' impossible to single out any one article for comment, but the contributions of Mr. G. W. Macdonald on the literature relating to researches on gunpowder, nitro-. glycerine, and nitrocellulose, with the full references to the original papers, will prove of considerable value.

that year to the appointment of Colonel Boxer to inspect and examine any mill, magazine or place " in which any kind of explosive was manufactured or kept. Later, a further disaster at Birmingham, by which fifty-three lives were lost, resulted in the ap pointment of permanent inspectors on the recommendation of the late Colonel Sir V. D. Majendie. K.C.B., who, as chief inspector. became so well known to the public at the time of the Fenian outrages. The Explosives Act of 1875 was the final outcome of these disasters, an Act which has proved of the greatest value through the tactful administration of the inspector> and the conscientious manner in which its provisions have been observed by the industry.

Special mention must be made of the bibliography and of the chronology. It is claimed for the former that it gives a complete list of the books on explosives published in England, whilst the the chronology covers the period 1242-1700, and is a remarkably complete work reflecting the greatest credit on those responsible for its compilation. The licences granted and the restrictions imposed for the sale of the ingredients of powder and for its manufacture are often

Subliming House for Sulphur at Feversham

Outside of what may be regarded as the purely scientific or technical articles, that on legislation, contributed by the editor, is of great interest. Although prior to 1860 there had been many Acts placing re

1 "The Rise and Progress of the British Explosives 'ndustry," Published under the Auspices of the Seventh International Congress of Applied Chemistry by its Explosives Section. Pp. xiv +418. (London: Whittaker and Co., 1909.) Price 15s. net.

extremely quaint and of great interest. This chronology should appeal to the antiquarian equally with the student of applied science.

In the second section of the book, devoted to description of existing factories, the information as to development, specialities of manufacture, organisation, &c., is very complete. Space only permits of reference to the articles dealing with Government