the validity of Prof. Wright's conclusions from the statistical evidence.

(5) This little book should be in the hands of every hygienist, and, since it deals largely with bovine tuberculosis, of every scientific stock owner. Behring is one of those who not only disbelieves the dictum of Koch of the essential distinction between human and bovine tuberculosis, but goes to the other extreme, and asserts that "the milk fed to infants is the chief cause of consumption," and he would insist on the pasteurisation of all milk. He asserts that pulmonary tuberculosis (phthisis or consumption of the lungs) is not an infection from inhaled tubercle bacilli. Besides pasteurisation, Behring also recommends the use of formalin as a preservative of milk, a procedure which will probably not commend itself to the authorities here, though there is a good deal to be said in its favour. Finally, he describes a method of vaccinating cattle against the tubercle bacillus by the aid of which he hopes eventually to stamp out bovine tuberculosis, and as a consequence human tuberculosis, a consummation devoutly to be hoped for. R. T. H.

THE PIONEERs of geoloGICAL THOUGHT. Karl Ernst Adolf von Hoff, der Bahnbrecher moderner Geologie. By Dr. Otto Reich. Pp. xvi+144. (Leipzig: Veit and Co., 1905.) Price 4 marks.

THIS

HIS clearly written work, undertaken with a just enthusiasm, is a welcome and permanent contribution to the biography of scientific men. Von Hoff's position as an original thinker is at least equal❘ to that of Lyell, though both writers, of course, found notable Bahnbrecher before them, in Hutton, Desmarest, and others. Karl von Zittel, in his "Geschichte der Geologie," held the balance very wisely between von Hoff and Lyell when he wrote, "The third volume (of von Hoff's "Geschichte der .. natürlichen Veränderungen der Erdoberfläche ") is clearly influenced by Charles Lyell's first volume of the Principles of Geology,' which had appeared in the meantime. Von Hoff unreservedly adopts the point of view of the great British investigator; yet Lyell's views corresponded on the whole with what von Hoff had put forward ten years before as the result of his historical researches. The fact that von Hoff's meritorious work was not properly valued, and was put in the shade by Lyell's epoch-making book, which appeared almost simultaneously, is easily explained by the circumstance that the modest German man of science derived his material mainly from books, that his position did not allow him to examine in the field the questions which he discussed, and that he enriched science by no new facts; he faced his problem as a historian, and not as an observer.”

Let us frankly admit, on the British side, that Lyell was not among the great original observers, and that his eminence rests on his brilliant perception of the meaning of correlated facts; yet his energy of movement and his frequent travels gave him an immense advantage over his contemporary. Dr. Reich shows us how von Hoff was occupied in many other affairs while preparing himself for his "Geschichte,"

a work of immense originality, and free indeed from the prejudices of his day.

In 1788 von Hoff entered the University of Jena, in his native region of Thüringia, and proceeded after two years to Göttingen. Here he found inspiration in the character and friendly help of Blumenbach; but his professional work lay in diplomacy, and in 1791 he was appointed Secretary of Legation under his own Government of Gotha, where his father was already a Privy Councillor. As in France, the scientific renaissance was accompanied by national movements that might well have extinguished private calm and study. Von Hoff was one of the delegates who, in 1806, pursued Napoleon's court from Berlin to Posen, and who secured the entry of Gotha into the saving grace of the Confederation of the Rhine. True to the interests of his State, he bore greetings to Jerome of Westphalia two years later, and helped to steer Gotha again into safe waters, this time under a German ægis, when Leipzig had seen the downfall of his alien suzerain. Yet, amid all the excitement of the times, when princes scampered rabbit-like from hole to hole, von Hoff founded a geological journal in 1801, met Werner in Gotha, and was struck by his mental limitations, spoke and corresponded heartily with Goethe, and explored the Thüringian Forest in a number of geological excursions. In the sanguinary year of 1806 he encountered Humboldt in Berlin, and the diplomat of Gotha was describing his native woodlands when the echoes of Friedland spread dismay through Germany.

In 1822 the first volume of his famous "Geschichte der durch Überlieferung nachgewiesenen natürlichen Veränderungen der Erdoberfläche appeared from the house of Justus Perthes in Gotha; and Dr. Reich does well to press the claims of this work as the foremost and most rational attempt to free geologistsfrom their popular catastrophic school. Dr. Reich (p. 107) quotes from Blumenbach to show that Hutton's views had spread to Germany in 1790, and that Voigt of Jena had already prepared the way by prior and independent conceptions of his own. Von Hoff surpassed Hutton in urging the power of existing causes working through long periods of time.. This position had been reached by him as early as 1801 (p. 111), and his biographer is inclined on this account to accuse Lyell of overshadowing wilfully his predecessor. It is idle, however, to quote from the edition of the "Principles of Geology" issued in 1872 (P 131), in which numerous alterations and additions had led to much excision. Instead of the solitary quotation from von Hoff referred to by Dr. Reich in support of his contention, we find five references in the first edition of vol. i. (1830), and two more in the second edition of vol. ii. (1833). Five references, moreover, to von Hoff remain in the eighth edition of the "Principles," issued in one volume in 1850. Since Lyell in his first edition devoted nine pages to the views of Hutton, out of the seventy given to the history of geology, he can hardly be said, as Dr. Reich would have us believe, to have shown ingratitude to Hutton also.

In 1826, in a memorial notice of Blumenbach, von

Hoff proved how far he was prepared to go in accepting organic changes as the result of changes of the earth's surface. Side by side with a progressive development of the surface-features, he saw the necessity for a transformation in the nature of the organic world. The quotation given on p. 134 may not imply so much as Dr. Reich reads into it; but we are grateful to him for setting before us the absolute mental pre-eminence of von Hoff in the world of Continental geologists of his day, and the fact that, from one cause or another, no conception of his greatness and originality can be gained from the historical résumé of Lyell, with which all English readers are familiar. G. A. J. C.

MINE AIR.

The Investigation of Mine Air. By Sir C. Le Neve Foster, F.R.S., and Dr. J. S. Haldane, F.R.S. Pp. xii+ 191; illustrated. (London: Charles Griffin and Co., Ltd., 1905.) Price 6s. net.

INCE the Hon. Robert Boyle published in 1671

SIN

his essays on "The Temperature of the Subter

raneall Regions" and on "The Strange Subtilty of Effluviums," and Athanasius Kirscher devoted a chapter of his “Mundus Subterraneus " (1678) to the occurrence of inflammable gas in the Herrengrund copper mines, there has been a constant succession of memoirs

dealing with the gases met with in mines. The latest addition to the series, by making accessible the results of German, French, and British investigations, should do much to add to the knowledge of the composition of mine gases and of their influence on human life. A large portion of the work was left in manuscript by Sir Clement Le Neve Foster at the time of his death, and

such revision as was necessary has been undertaken by Dr. J. S. Haldane, who has added a section of great value, embodying a description of rapid methods of analysis that he himself has devised and an essay on the interpretation of mine-air analyses in the light of recent investigations.

The book is of a composite nature. The first section is a translation of the introductory treatise on mine-air analysis by Prof. O. Brunck, of the Freiberg School of Mines. The second section is a translation of a paper by Mr. Léon Poussigue on the measurement of air currents and fire damp at the fiery Ronchamp collieries, the deepest mines in France. The third and longest part contains a summary of Dr. Haldane's work on the examination of mine air. As an appendix is added a detailed account, from Sir Clement Le Neve Foster's reports to the Home Secretary, of the effects of carbonic oxide in connection with the Snaefell mine disaster in the Isle of Man in 1897. Sir Clement's exposure to carbonic oxide during the recovery of the bodies of the miners killed was the starting-point of the illness that ultimately proved fatal.

The methods of analysis for mine gases described by Prof. Brunck are simple, and in no respect less accurate than the most delicate methods of exact gas analysis. The fulness of the instructions and the simplicity of the methods should induce mining engineers to practise gas analysis and to regard it as an impor

tant guide to the safety of the workings placed under their charge.

Since November, 1891, a special department has been organised at the Ronchamp collieries for the purpose of determining the proportion of fire-damp in the workings. The Le Chatelier combustion apparatus is employed, and an assistant makes two hundred determinations a day.

In the third section the methods of determining oxygen, carbonic anhydride, nitrogen, and fire damp described by Dr. Haldane well fulfil the practical requirements of being very accurate and rapid. His method of obtaining and transporting samples of mine air in two-ounce stoppered bottles is trustworthy and much more convenient than Poussigue's method of using a 1-litre bottle, or Winkler's method of using a 10-litre sheet-zinc vessel recommended by Brunck. One cannot help thinking that in the latter case prolonged storage in a zinc vessel would have an effect on the composition of the gas. In Dr. Haldane's dry bottles no sensible alteration of the contained sample occurs within a fortnight or more. His method of gas analysis is similar to that originally described by him in the Journal of Physiology in 1898; and he now describes for the first time a portable apparatus, enclosed in a wooden case measuring 7 by 12 by 2 inches terminations may be made, on the spot underground, of and weighing 51lb., by means of which accurate devarious impurities in the air. He also describes a convenient method of determining the quantity of stonedust in the air of working places in metalliferous mines. The disastrous effects produced by the habitual inhalation of air containing stone-dust are now generally recognised. The air of an "end" or "rise " just after blasting contains large quantities of dust, and the men ought not to return until there is less than 1 milligram in 10 litres of air. The average air of a stope" where men are working should not yield any weighable dust in that quantity of air.

66

It is

Obviously a complete analysis of mine air is useless unless the significance of the results is understood. The chapter on the interpretation of mine-air analyses is consequently of far-reaching importance. Dr. Haldane advocates the use of the convenient term "black damp" for the nitrogen and carbonic anhydride. It is the gaseous residue resulting from the slow oxidising action of air on oxidisable substances in a mine. very commonly confused with carbonic anhydride, but it really consists chiefly of nitrogen. Black-damp, which was nothing but pure nitrogen, was described by Mr. H. A. Lee (Proc. Colorado Scientific Society, vol. vii., p. 163, 1904) as occurring in a metalliferous mine in Colorado. A useful section on the effects of air impurities on men concludes part iii. Much of the information in this part has already been published by Dr. Haldane in Home Office reports and in papers read before the Institution of Mining Engineers; but an authoritative summary of the results arrived at is a welcome addition to technical literature.

The book, which was originally intended for Le Neve Foster's students at the Royal School of Mines, should prove invaluable, not only to mining engineers at collieries, but also to those engaged in metalliferous, mines. B. H. B.

AN INDIAN GARDEN.

An Indian Garden. By Mrs. Henry Cooper Eggar. Pp. viii+181; illustrated. (London: John Murray, 1904.) Price 7s. 6d. net.

AN unpretentious little book, written in an easy

vein, printed on very light paper and in the best of type, "An Indian Garden" might well be suited to while away pleasantly an idle hour. There is so much freshness about the book, so much enthusiasm for the author's garden, such a lovable unconsciousness of the inward triviality of the hundred and one little incidents, servant, cobra, and dog stories and harmless gossip woven into this tale of amateur gardening, that one would fain make the personal acquaintance of the writer. As we read on, our interest centres more and more in the healthy, vigorous, and amiable personality that sways this old Indian Garden of 5 acres, whilst the garden itself, with its old trees, its amaryllis and caladium beds, its fernery, its obstreperous lawn of "Dooba " grass (Cynodon Dactylon), and its general propensity to run back to jungle, becomes so much background.

In those circumstances one forgets to look out for any systematic information on the conditions of gardening in India, nor is there any room for criticising seriously the author's botany. One does not stop, for instance, to ponder over the curious " almond tree" (p. 43) with the convolute embryo, or mind that the lycopodium (p. 50) "that turns a beautiful electric blue in the shade" is in reality a Selaginella (S. uncinata), or that the deodars (p. 141) which ripen their berries in July are evidently the debdars (Polyalthia longifolia) mentioned repeatedly in the earlier pages. It must all be beautiful, and one longs to

see it.

We are not told where the garden is. Its whereabouts, like other things in the book, are hidden under a delightful incognito. It is just a few feet above the sea in a vast plain "with never a rise, sufficient to be called a hill anywhere near for 100 miles." It may be, and very likely it is, in Bengal, as the locality from which the preface is dated and other indications suggest; but that, again, matters very little. It is in keeping with the light, playful humour which pervades the whole book. Still, it would be unfair to pass over the fact that there are passages in it which for keenness of observation, terseness and descriptive power, rise high above the average level of the book. Thus on p. 41, “I like the Casuarinas, though they are bad gardeners, and suck up all the moisture in the earth for some long distance round their roots, so that nothing can possibly live near them; sometimes in the early morning they weep it all back copiously like rain "; or on p. 145, "If one wanted to photograph the movements of an opening blossom, one should select the Crinum augustum. It is a noble plant, this lily; about 4 feet high, with scented flowers, numbering 22 in a bunch at the end of a long stalk as thick as a ruler. I passed by one just after a shower of rain this evening, and noticed that four or five of the 4 inch long, pink-striped buds were just ready to open. I came

by again shortly after, and lo and behold! they were open, quite wide open, too. In my next turn, 20 minutes after, the long petals had entirely curled themselves backwards like rams' horns. One could see them all a-quiver with the intensity of the movement still. In one hour the points of those petals must have described an arc of 8 or 9 inches or more! "

There is a dainty coloured frontispiece representing a branch of an Antigonon (evidently A. leptopus)—— though it is difficult to see why a representative of an exclusively American genus should usher in "An Indian Garden "—and eighteen illustrations, photographic prints, some of them veritable gems for their general beauty and exquisite clearness.

OUR BOOK SHELF.

OTTO STAPF.

Pp.

Animals I Have Known. By A. H. Beavan. 304; illustrated. (London: T. Fisher Unwin, 1905.) Price 5s.

IF the present rate of issue be much longer maintained, popular books on mammals (or "animals," as they are still called by the man in the street) will soon begin to rival in number those In the volume before us the author, devoted to birds. without having anything specially new to communicate, discourses pleasantly enough on the mammals (both wild and domesticated) of our own islands, as well as on those of two other countries, namely, Australia and South America, with which he is personally familiar. His anecdotes and descriptions are emphasised by the numerous reproductions from photographs with which the work is illustrated. Most of these are first rate, the one of the thylacine, or Tasmanian wolf, showing to perfection that gradual merging of the tail in the body to which the author specially alludes, and which so markedly distinguishes many of the lower mammals from their more specialised relatives.

Unfortunately, the text is marred by a number of more or less inexcusable blunders and errors, which cannot but deceive the class of readers for whom the book is intended. On the very first page we are told, for instance, that there lived in Britain during the mammoth period "tapir-like three-hoofed creatures with long snouts." This can evidently be nothing else than the Oligocene palæotherium, an animal to which reference is again made on p. 279, where the author observes that he has momentarily forgotten its name-a nice admission to make in print! A similar "muddle" in regard to palæontological chronology is made on p 16, where we find opossums included among the British Pleistocene fauna. Even more serious is the deliberate statement on p. 222 that the duckbill, or platypus, is the only known oviparous animal-more especially in view of certain doubts that have been expressed of late years as to whether this species does actually lay eggs. Again, on p. 291 we are told that all South American monkeys are furnished with prehensile tails, while ten pages later we are informed that the vampire bat taps the blood of its victims with its canine (instead of incisor) teeth. Moreover, in the plate on p. 299 the author figures as that of the true blood-sucking vampire the head of a javelin-bat (Phyllostoma) or a nearly allied species. Possibly the latter species may occasionally suck blood, but it is not the vampire par excellence. In the figures of a bat on p. 91, which

may be presumed to be intended for the pipistrelle, the tail is entirely omitted, so that there is nothing to support the median extension of the interfemoral membrane ! The following remarkable sentence (p. 202), we are glad to acknowledge, is not typical of the author's style :-"The koala's habits are sluggish, and though able to climb well, moves about the trees in a most deliberate manner." R. L.

Queen-Rearing in England, and Notes on a Scentproducing Organ in the Abdomen of the WorkerBee, the Honey-Bees of India, and Enemies of the Bee in South Africa. By F. W. L. Sladen. (Houlston and Sons, 1905.)

THE Scope of this little work by a practical beekeeper is sufficiently indicated by its title, and the bulk of its contents has already appeared in the British Bee Journal and the Entomologist's Monthly Magazine. There is a coloured frontispiece representing the queen and worker of the Golden Italian bee, and there are numerous text-illustrations of no remarkable excellence After a chapter on queenrearing in nature, several chapters are devoted to the best artificial means of securing a supply of queens for multiplying or improving bee-colonies; and a brief account is given of different races called the Italian (or Ligurian) Bee, the Golden Italian Bee, and Carniolan Bee, and the Cyprian Bee. In a later chapter Mr. Sladen remarks that when vibrating their wings, and especially when swarming, bees produce a peculiar tune which has been supposed to attract their comrades; but the author thinks the attraction is at least partly due to a powerful scent emitted when a membrane situated between the fifth and sixth dorsal segments of the abdomen is exposed. This is fully described and figured. Short chapters on the honey bees of India (Apis dorsata, florea, and indica), and on enemies of bees in South Africa; "Bee Pirates " (sandwasps belonging to the genera Palarus and Philanthus), a Tachinide parasite in the abdomen ; and a species of Chelifer conclude the work.

Pp.

a

Physical Experiments. By N. R. Carmichael. xi+127; with diagrams. (Kingston, Ontario: R. Uglow and Co., 1904.) ANYONE drawing up an elementary course of mechanical and physical experiments, and wishing for manual to accompany it so as to make the preparation of a special volume unnecessary, could hardly do better than adapt his course to the manual before us. It contains just the short description which would otherwise be produced by some copying process for distribution to a class, or, failing this, would probably be written on a blackboard. That is to say, there is just enough description to indicate to a pupil what he is expected to do, and which would be copied by him into his notebook. A teacher will require to amplify the book verbally, either in the course of a short demonstration at the beginning of the class, or, if his lectures and the practical work run together very well, this might sometimes be done in the course of the lectures. The aim that Mr. Carmichael has had before him has been to state concisely the nature of the quantity to be measured in each experiment and the theory underlying the method suggested. Descriptions of instruments are entirely omitted, as the students are expected to have the apparatus given them by an instructor.

With regard to the selection of experiments, the object has been to give students who have but a limited time for laboratory work a practical acquaintance with as many physical quantities as possible. The

fact that the author is a teacher in a school of mining is a guarantee that the technical student is intended to be served; but it is the more academic, but equally necessary, side of his training that is here catered for. An Introduction to Elementary Statics (Treated Graphically). By R. Nettell. Pp. 64. (London : Edward Arnold, 1905.) Price 28.

THIS book consists of a set of graduated exercises in graphical statics. The first seventy, about half the total number, are restricted to problems on the equilibrium of three forces at a point, and are intended to be worked by means of the parallelogram of forces. In succeeding problems the triangle of forces and the polygon of forces are introduced. The principle of moments is also employed. A few examples are given of the determination of the centre of gravity of simple plane figures, and in the final examples the subject is carried as far as the equilibrium of four non-concurrent forces in one plane. The link polygon is not used, so that parallel forces are scarcely referred to. It will be seen how extremely limited is the ground covered by this book. The constructions are not founded on or verified by experimental work of any kind. No vectors other than force vectors are introduced. Trigonometrical calculations, even of the simplest kind, are rigidly excluded. The book is intended to be used by classes of young boys, but its scheme does not harmonise with the ideas now prevalent as to the way in which ele mentary mathematics should be taught to youths. The Elements of the Differential and Integral Calculus. By D. F. Campbell. Pp. x+364. (New York: The Macmillan Co.; London: Macmillan and Co., Ltd.. 1904.) Price 7s. 6d.

THIS book seems well adapted to serve as a text-book for a first course in the differential and integral calculus. Fourteen chapters deal with the differential calculus and its applications to maxima and minima values, expansions in series, and the geometry of plane curves. The fundamental ideas of integration are very fully explained, the second fourteen chapters being devoted to the integral calculus and its application to finding plane areas, lengths of curves, areas of surfaces, and volumes. In a short chapter dealing with approximate integration, the first and second elliptic integrals are introduced, and three-figure tables for F(k, ø) and E(k, 4) are given. A few elementary chapters on mechanics have been introduced, so that the student may be able to view from the mechanical, rather than from the purely mathematical, side the principles of attraction, centre of gravity, and moment of inertia. Numerous exercises, with answers, are given with each chapter. The diagrams are clear, and the type is excellent.

Völkerpsychologie. By Wilhelm Wundt. Vol. i. Die Sprache. Second revised edition. 2 parts. Pp. xv+667, x+673. (Leipzig: Wilhelm Engelmann; London: Williams and Norgate, 1904.) Price 145. net and 155. net; bound, 178. net and 18s. net. THE first volume of this monumental work has reached a second edition, some sixty or seventy pages bulkier than its predecessor (reviewed in NATURE on January 16, 1902). The most important changes affect the fourth chapter, Der Lautwandel, the sixth. Die Wortformen, and some parts of the theory of the sentence. A first edition of the other volumes, dealing with myth and custom, has not yet appeared; it is to be hoped that it will not be unduly delayed by the necessity of revising the present instalment, and that in any parts still to appear the wood will be less closely concealed by the trees.

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.]

History of a White Rhinoceros Skull.

Is his interesting "Natural History Essays," in which occurs the description of the white rhinoceros, Mr. Graham Renshaw makes the following reference to the first skull of this animal which was brought to England :

"It would be interesting to know if the white rhinoceros head brought to England by the Rev. John Campbell, about 1815, is still in existence. It appears to have been preserved as late as 1867 in the Museum of the London Missionary Society at Finsbury, but there seems to be no mention of it during recent years in zoological literature. In a figure now before me the artist has absurdly furnished the open jaws with an imaginary series of perfectly regular pseudomolar teeth: the square mouth has been distorted to resemble the prehensile lip of the black species, though the slit-like nostrils, position of the eye and semi-tubular ears are delineated with fair correctness. The anterior horn of this individual is said to have been 3 ft. long: and, as figured, from its slender

ness recalls Col. Hamilton Smith's description of the mysterious horn, brought from Africa, from which he sought to deduce the existence of a true unicorn in the interior of that Continent (p. 146).

as

In 1902 this very skull was purchased from Mr. Cecil Graham for the American Museum of Natural History by Mr. J. Pierpont Morgan. Mr. Graham has made a large and valuable collection of rhinoceros horn weapons, clubs, knob-kerries, and battle axes, and in course of correspondence he wrote of his discovery of the skull follows:-" There is no record as to how or when the specimen was first brought to England. I found it by chance a few years ago in the City, lying neglected and dirty on the floor of a back room of the London Missionary Society. No doubt it was presented by a missionary before 1821. I especially value the letter dated .1821."

The letter referred to by Mr. Graham is from William Cooke, of the Royal College of Surgeons. It is dated November 20, 1821, and addressed to William Alers Hankey, Esq., Fenchurch Street. It reads as follows:"My dear Sir,

"The head in the missionary museum supposed to be the head of the unicorn, appears to belong to a species of Rhinoceros previously unknown in this country, at least, there is no such specimen in the Hunterian Museum which may be regarded as the National Depository for comparative anatomy. In that grand collection there are

heads which nearly resemble it, but there are points in which the diversity of conformation indicates a decided specific difference.

"Permit me to suggest to you, and through you to the Directors of the Missionary Society, that a rare specimen of that nature is entitled to a place where it can be more justly appreciated than it ever will be in their collection. I need not suggest to you the advantages which result from a concentration of the different productions of nature -from bringing under one view the genera and species of the various natural sciences-especially when they are not only rendered available for minute distinction, but by a liberal policy are accessible to men of science from all parts of the world. I can have no selfish motive in suggesting that the head possessed by the Missionary Society would become much more an object of interest if deposited in the Hunterian Museum, than it ever will be should it remain in the Old Invry. If deposited at the College of Surgeons it will not only fall under the notice of Naturalists from all quarters, but it will likewise be a subject of reference in the lectures on comparative anatomy annually delivered at that Institution.

The Missionary directors unquestionably will consider the advantages which may result to their own Society, as well as the promulgation of scientific knowledge; and if I might presume to express an opinion on this subject, it would be in favour of the head being presented to the College. It would there be preserved as a testimony of praiseworthy liberality-it would soften prejudice, where perhaps there is a deep-rooted antipathy to religion, but where conciliation is of great importance; and if it remain in its present situation for a few years it will be liable to destruction, or to essential injury at least.

"If you have never seen the Museum of the College of Surgeons it would afford me great pleasure to accompany you thither any Friday.

"I feel assured, my dear Sir, that you will excuse the liberty I have taken in addressing you on this topic;—and believe me to be

"Yours most obediently and

(Measured on a straight line.)

The skull is now exhibited with two war clubs manufactured from the nasal frontal horns of the white

rhinoceros, with a skull of the related woolly rhinoceros from Siberia, presented by the Moscow Museum, through Madame Pavloff, also with a skull of the Rhinoceros pachygnathus, a related or ancestral form, from Pikermi, presented by the Munich Museum through Prof. von Zittel. HENRY FAIRFIELD OSBORN. American Museum of Natural History, New York, April 24.

Fictitious Problems in Mathematics.

YOUR reviewer gives a new definition of "a perfectly rough body (NATURE, June 1), which he says is that of the mathematician. The definition appears to me to contradict what he has elsewhere said. But I need not enlarge on this point, for his criticism of a problem should be tried, not by his definition, but by that given in the book in which the problem occurs.

The reviewer accuses Cambridge examiners "of endowing bodies with the most inconsistent properties in the matter of perfect roughness and perfect smoothness