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VARIOUS adaptations of filter-paper to chromatography have been published1–4 ; the following technique has advantages of simplicity of apparatus, speed, reproducibility, and particular suitability for micro-analysis. (Sensitivity approximately 2 micrograms solute.)

WE have already described a fortuitous combination of events which led to the discovery that American newspapers and other paper products contain a potent analogue of the juvenile hormone of the European bug, Pyrrhocoris apterus L. (Heteroptera ; Pyrrhocoridae)1. When reared in contact with ‘active paper’ or when exposed to surfaces impregnated with extracts of the ‘paper factor’ (PF), fifth-stage Pyrrhocoris larvae undergo one or more supernumerary larval moults and finally die without completing metamorphosis or attaining sexual maturity. This same result is observed when 1 µg of partially purified PF is topically applied to young fifth instar larvae1,2.

EVERY one interested in the study of physics of the more profound kind will welcome this collection of essays by the celebrated natural philosopher, so many of which, hitherto scattered throughout various periodicals, difficult to gather together, or even wholly inaccessible to readers out of the reach of large public libraries, are yet of decisive importance for those chapters of the science to which they refer. With the two volumes now before us, in conjunction with the late publication, “Reprint of Papers on Electrostatics and Magnetism,” the collection is now completed down to the date of February, 1856. Vol. II. contains, besides, all that the author has written on the Transatlantic Telegraphs, which, according to the strict order of time, might have been looked for in later volumes. The first volume begins with a series of essays, for the most part of a mathematical nature, ranging from the year 1841 to 1850. So far as these essays relate to physical problems, their - chief interest turns on the difficulties connected with the analytic method. These difficulties were, however, even at that early period, treated by the youthful author with great skill, and under comprehensive points of view. The problems are, in part, geometrical and mechanical, referring to lines of curvature, systems of orthogonal surfaces, principal axes of a rigid body, &c. Most of them, however, deal with the integration of the differential equations, on which is based the doctrine of thermal conductivity and potential functions. The latter, as is well known, form the mathematical foundation of a large number of chapters in physics—the doctrine of gravitation, of electrostatical distribution, of magnetic induction, of stationary currents of heat, of electricity and of ponderable fluids. By treating all these problems collaterally and rendering concretely in some what in others appears in the highest degree abstract, the author has succeeded in overcoming the greatest difficulties, and we can only recommend every student of mathematical physics to follow his example. A field particularly favourable for the exercise of his powers was opened up to Sir W. Thomson by the phenomena, newly discovered by Faraday, in diamagnetic and weakly magnetic bodies, crystalline as well as uncrystalline. These our author rapidly and easily succeeded in arranging under comprehensive points of view. One great merit in the scientific method of Sir William Thomson consists in the fact that, following the example set by Faraday, he avoids as far as possible hypotheses on unknown subjects, and by his mathematical treatment of problems endeavours to express the law simply of observable processes. By this circumscription of his field the analogy between the different processes of nature is brought out much more distinctly than would be the case were it complicated by widely-diverging ideas respecting the unknown interior mechanism of the phenomena. Mathematical and Physical Papers. By Sir William Thomson. Vols. I. and II. (Cambridge University Press. 1882, 1884.)

I CAN add to the testimony of Mr. Charles Taylor about the efficiency of a screen of tracing paper. I have used for several years a small screen of tracing cloth mounted on rollers like a map. It is very portable and soon fixed. With a sciopticon lantern (oil lamp) I have shown transparencies in the winter months to an audience of seven hundred men in a Midland Railway mess-room during the breakfast hour—8.15 to 8.50 a.m.—though the windows are by no means in the best position, and the room is lighted by skylights as well as by side windows. It is a pity this screen is not better known and more extensively used for scientific lectures.

WHEN Sir Joseph Larmor edited the scientific papers of Lord Kelvin and Prof. Fitzgerald he did work which nobody else could have done so perfectly; his time, however valuable, was spent to advantage. The editing of these papers of Lord Kelvin's brother might have been undertaken by many others, but now that the excellent result is before us we cannot regret it, and we must confess that we did not expect to find in the editor such a perfect sympathy with James Thomson's methods of study. He shares with Prof. Thomson's son the honour and credit of this publication. The book begins with about a hundred pages of biography and comment upon Thomson's works—excellent reading. Then we have 153 pages of papers relating to fluid motion, dating from 1852 to the Bakerian lecture of 1892; nearly eighty pages on congelation and liquefaction from 1849 to 1888; forty pages on the continuity of states in matter from 1869 to 1873; seventy pages on dynamics and elasticity from 1848 to 1887; and about eighty pages on geological and miscellaneous subjects from 1848 to 1892. Collected Papers in Physics and Engineering. Prof. James Thomson, F.R.S. Selected and arranged with unpublished material and brief, annotations by Sir Joseph Larmor, Sec. R.S., and James Thomson. Pp. civ + 484. (Cambridge: University Press, 1912.) Price 15s. net.)

Hochspannungselektrophorese ihre Anwendungsmoglichkeiten fur Biochemische und Klinisch-chemische Trennprobleme By Dr. Med. Roman Clotten, Dr. Med. Annemarie Clotten. Pp. xv + 556. (Stuttgart: Georg Thieme Verlag, 1962.) DM.98

IF we take a somewhat different course in reviewing this work from that which we should naturally adopt with works professedly scientific, we hope at least to justify our conduct to the reader before we finish. For, alas, all is not scientific that professes to be science, and even celestial minds can harbour very curious feelings and express them with most unmistakeable vigour, while not always striking above the belt. Wissenschaftliche Abhandlungen (Erster Band). Von F. Zollner. (Leipzig: L. Staackmann, 1878.)

ACCORDING to a statement in his biography, recently published, Bateson intended at some time to write the history of Mendelism. Interesting as such a review would have been, the result has, in effect, been accomplished by the publication of his scientific papers and public addresses; for we have here not only a record of English work covering the early days of Mendelism, but also a general summary of much of the work done elsewhere. These papers, taken in conjunction with Bateson's biography, tell nearly the whole story of the fateful years following the rediscovery of Mendel's work in 1900. Possibly, in retrospect, emphasis might now be differently placed, and much of the detail relegated to the background, but the vividness of the recital by those in the midst of the enthusiasm of verifying and expanding Mendel's work might be lost in a strictly historical review. Scientific Papers of William Bateson. Edited by R. C. Punnett. Vol. 1. Pp. viii + 452 + 7 plates. Vol. 2. Pp. viii + 503 + 29 plates. (Cambridge: At the University Press, 1928.) 42s. net each.

The Papers of Wilbur and Orville Wright Including the Chanute–Wright Letters and other Papers of Octave Chanute. Edited by Marvin W. McFarland. (Sponsored by Oberlin College on the Wilbur Wright Memorial Fund, and prepared for the Press, with Notes, Appendices, and Bibliography, by the Aeronautics Division of the Library of Congress.) Vol. 1: 1899–1905. Pp. lv + 676 + 141 plates. Vol. 2: 1906–1948. Pp. xxvii + 677–1278 + plates 142–236. (London: McGraw-Hill Publishing Company, Ltd., 1953.) 2 volumes, £10.

MATERIALS composed of American paper-pulp have been shown to contain an extractable, heat-stable lipid which exhibits high juvenile hormone activity when topically applied or otherwise brought into contact with the European bug, Pyrrhocoris apterus L. (Heteroptera; Pyrrhocoridae1,2). The active principle is synthesized by certain species of pulp trees—more particularly, the American balsam fir (Abies balsamea). The ‘paper factor’ (PF) proves to be an extremely potent analogue of the juvenile hormone of Pyrrhocoris apterus3. Yet, so far, it has proved completely inactive when tested on other laboratory insects including two other species of Heteroptera—Oncopeltus fasciatus (Lygaeidae) and Rhodnius prolixus (Reduviidae)1,2.

THE Royal Meteorological Society is to be congratulated on its decision to reprint the scientific papers of Mr. W. H. Dines as a memorial to that eminent meteorologist. The book, which has now appeared, fulfils its purpose admirably and is a credit to the Society as well as an honour to one of its most distinguished fellows. England owes a great deal to its band of amateur men of science, and meteorology probably owes more to the amateur than any other of the major branches of science. Mr. W. H. Dines was an amateur in the best sense of the word. He took up meteorology because it made its own appeal to him, no doubt influenced to some extent by the meteorological work of his distinguished father, Mr. George Dines. This compilation of his papers brings home to the reader what a large part Dines played in the development of scientific meteorology in Great Britain; but it also helps those of us who knew the man and read each one of his papers as it appeared to see his work as a whole, and to judge how much of it will be of permanent value and how much of it was laying the foundations on which others have built. It is probably in the last respect that Dines made his greatest contribution to science. Throughout his scientific life Dines was a pioneer; he had the instincts of a pioneer, and the methods of a pioneer. His tools were always of the crudest, without any refinement and without any unnecessary accuracy, but capable of doing the job for which they were designed. Collected Scientific Papers of William Henry Dines, B.A., F.R.S. Pp. x + 461. (London: Royal Meteorological Society, 1931.) 15s. net.

Collected Papers of R. A. Fisher. Edited by J. H. Bennett. Volume I. 1912–24. Pp. 604. (The University of Adelaide: Adelaide, 1971.) A$17; US$20.

Papers of the Society of Mural Decorators and Painters in Tempera. Second volume, 1907–1924. Edited by John D. Batten. pP. V+134+6 plates. (Brighton: Printed for the Society by the Dolphin Press, 1925.) 10s. 6d.

“WITH respect to the main facts of Geology, we geologists are in general of one opinion but with respect to the explanation of many of those facts, we hold very divergent opinions” In these opening words of his preface, the author explains and justifies the publication of this collection of essays. Prof. Prestwich's position, as the acknowledged doyen among British geologists, demands that these articles—the latest fruits of his ripe experience—should receive the most thoughtful consideration from his fellow geologists; but, quite apart from the position and authority of their author, all of the memoirs included in this volume are of the greatest value as contributions to science; and in reading them it is difficult to say whether we are more impressed by the wealth of knowledge or the literary grace which they display. Collected Papers on some Controverted Questions of Geology. By Joseph Prestwich, Corr. Inst. France (Acad. Sci.); Acad. R. Lyncei, Rome; Imp. Geol. Inst., Vienna; Acad. Roy., Brussels; Amer. Phil. Soc, Philad.; &c. (London: Macmillan and Co., 1895.)

IN this volume of essays, all the product of the last three years, we have the revelation of the thoughts on our present discontents of a student of science turned publicist and perhaps the most qualified of living writers to express either the implications of the scientific outlook in the life of society or the responsibilities which fall on the shoulders of scientific workers. After Democracy: Addresses and Papers on the Present World Situation. By H. G. Wells. Pp. vii + 247. (London: Watts and Co., 1932.) 7s. 6d. net.

THIS is a book calculated to rejoice the heart of an educational worker, not so much for the wisdom it contains as for the evidence it affords of the spirit animating the educational policy of our leading English schools for girls. Here we have twenty-four essays relating to the subjects of girls' education, written by experienced headmistresses, who one and all seem to have a real zeal for their work, and a humble-minded desire to find the best way of doing it. There is a sense of sincerity, earnestness, and warmth in the essays that is highly pleasing, and a willingness to look at new proposals and plans that contrasts most favourably with the self-confidence, and subacid raillery sometimes affected by the high placed pedagogue. Public Schools for Girls: a Series of Papers on their History, Aims, and Schemes of Study, by Members of the Association of Headmistresses. Edited by Sara A. Burstall M. A. Douglas. Pp. xv + 302. (London: Longmans, Green, and Co., 1911.) Price 4s. 6d.

THE early stages in the life-history of recent crinoids have always been regarded with interest, because it was hoped that they would throw light on the evolution of this class, so rich and various in ancient seas, and on its relation to the other very differently fashioned classes of Echinoderma. Unfortunately, the only forms that have up till now furnished material for the em-bryologist are the unstalked comatulids, or feather-stars, and in the past such material has come from but a single genus, and from only three closely allied species of it—Antedon bifida of our own coasts, A. mediterranea, and A. adriatica. The accounts of their development by W. B. Carpenter, Bury, Seeliger, and others have shown slight differences, due, in part, probably to specific distinctness of the material. Even if it were not feasible to obtain the early stages of any stalked crinoid, still a study of other species, representing other genera of comatulids, was much to be desired, since it might then be possible to infer which features were peculiar to Antedon and which were common to comatulids generally, if not to the whole class Crinoidea. Such a study has now been made by Dr. Morten-sen, who has obtained a fairly complete series in four genera, and the pentacrinoid larvae of two others. His results are set forth in clear English with his usual care, and the memoir is illustrated by admirable drawings from his own pencil. His many interesting results are discussed in a “General Part” which demands the attention of professed morphologists. Here we shall select for comment a few observations that bear on the past history of the class. Papers from the Department of Marine Biology of the Carnegie Institution of Washington. Vol. xvi. Studies in the Development of Crinoids. By Th. Mortensen. (Publication No. 294.) Pp. v + 94+xxviii plates. (Washington: The Carnegie Institution of Washington, 1920.) 6 dollars, post free.

THIS book is the work of an enthusiast, but to find fault with enthusiasm in these days of rapid progress and fresh discoveries would be unwise. Mr. Rider Haggard, with his watchword “Back to the Land,” and Sir Seymour Haden, with his advocacy of “superficial and coffinless burial,” are both enthusiasts. Who will venture to say that Mr. Rider Haggard or Sir Seymour Haden or Dr. Vivian Poore are idle dreamers? None dare say this, and if in some directions the writer of this review ventures to dissent from Dr. Poore's conclusions, it must be understood that he does so in a spirit of tolerant sympathy with the author's main contentions. 1 In the first six chapters, the distinguished author seeks to show that such diseases as tetanus, anthrax, diarrhoea, dysentery, cholera, Malta fever, malaria and enteric fever have not been proved to be “soil diseases” in the proper sense of the term. That is, that the prominent part assigned to soil in the spread of disease among human beings is largely speculative in character. At the same time, the author freely admits that contaminated soil may occasionally (accidentally, as it were) be the means of causing isolated attacks or even localised outbreaks of certain diseases. Nevertheless, he refuses to regard the soil as a “breeding ground” for pathogenic microbes or as capable of exerting any sustained power of spreading disease. On the contrary, he considers the soil effective in bringing about the dissolution of harmful germs. The Earth in Relation to the Preservation and Destruction of Contagia, being the Milroy Lectures delivered at the Royal College of Physicians in 1899, together with other Papers on Sanitation. By George Vivian Poore (Lond.), F.R.C.P. Pp. 257. (London-Longmans, Green and Co., 1902.)

THE discussion started by Mr. J. Swinburne in NATURE of June 29, seems to have wandered from its original purpose, and from the points suggested in your article of July 13. It is the duty of an investigator in any branch of Natural Science to publish the results of his research if they appear to be both new and of sufficient interest. He has three courses open to him. He can write a book, relying on the advertisements of his publisher and on reviews to inform other workers that such a book exists. His space is unlimited, but he cannot make sure of a circulation unless by presentation copies. He may communicate his results to a scientific society. His space is somewhat limited, but he secures a definite circulation, and an opportunity for discussion. Or he can communicate them to some technical journal, securing generally the maximum circulation, but with considerable restriction as to space.

THE method advocated by Mr. J. C. McConnel (NATURE, February 13, p. 342) would undeniably be feasible. But I should pity the fellow-craftsman who should have to carry it out. The idea of numerical subdivision has been worked out by Prof. Dewey with great ingenuity and industry in his “Decimal Classification and Relative Index,” 1885. We find, on referring to p. 31, that 016·9289551 will indicate the “Bibliography of Persian poets.” Natural science occupies a place from 500–600, and does not seem to have been as yet reduced to an equal degree of elegant simplicity, for the subject of “observing chairs, &c.,” is merely denoted by 522·28.

IN the “Mathematical Papers” (pp. 628-37) I was able to print the syllabuses of a series of ten lectures delivered by Prof. Clifford to a class of ladies at South Kensington in the spring and summer of 1869. Whilst turning over a collection of miscellaneous papers, in a box, Mrs. Clifford and I had the good fortune to light upon a manuscript quite ready for printing, and this (“Mathematical Papers,” p. 628) subsequently formed part of the volume on “Seeing and Thinking;” but we could not find any trace of any more manuscript of the above-mentioned series of lectures. Just before the recent Easter holidays Prof. Karl Pearson returned to me a few pages of manuscript bearing on the International Scientific Series volume which I had lent him, and with them he sent me a large note book which had been in the late Prof. Rowe's hands. On opening this book I at once saw that it contained very full notes of other lectures of the course. In fact, Lecture II. (“On Plane Surfaces and Straight Lines”) is quite ready for press, as is also, I think, Lecture III. (“On the Rotation of Plane Figures”); Lecture IV. (“Of Similar Figures”) is a fragment, and still more fragmentary is Lecture V. (“The First Principles of Calculation”). Of Lecture VI. (“The Theorem of Pythagoras”) there are two loose sheets of figures: on one sheet is “the Bride's Chair,” and the figures on this and the other sheet show that my information was correct, and that the remarks on pp. 633, 637 are ad rem. As Lecture IX. (“On the Shadows of a.Circle”) is very fully illustrated in the recent volume edited by Prof. Pearson, we see that we are in possession of a fairly complete presentment of Prof. Clifford's views on the subjects of the course of lectures.

THE discussion of this important subject has been started a propos of physical papers, but the publication of papers in all branches of science is in an equally unsatisfactory state.

I HAVE observed a curious optical effect which I have not seen described anywhere. If an open book is illuminated fairly strongly from one side, for example, from over one shoulder, the general colour of the white paper is different for the two eyes when one or the other is closed. The effect has been tried with several subjects with the same result. When the light comes over the left shoulder and the left eye is open the pages have a bluish tinge ; when the right eye is open and the left closed the tinge is reddish. If the light comes over the right shoulder the above effects are reversed. If the light is centrally placed above and behind the head there is no difference.

WE have completed a psycho-physical study of the gloss of several series of coated and uncoated papers differing widely in surface finish and in colour, including a black, a green and a mauve, besides an assortment of shades of white, cream, yellow and brown.

Selected Papers of Arthur William Conway Edited by Prof. James McConnell. Pp. viii + 222. (Dublin: Dublin Institute for Advanced Studies, 1953.) 21s. net.

IN his criticism on a paper of mine on the partition of energy in a set of non-homogeneous spheres (NATURE, March 31, p. 512), Mr. Watson says that the conclusions are vitiated owing to my having omitted to introduce the frequency factor of collisions before proceeding to take the averages. This is not exactly accurate, since a frequency factor is introduced, viz. the relative speed of the centres of inertia of the impinging spheres parallel to the line of impact.

ON reading the article entitled “Juvenile Hormone Activity for the Bug, Pyrrhocoris apterus”, by Slama and Williams1, I was struck by a likely correlation.

As part of an investigation at this Station into the reproductive physiology of sheep, a suitable light source was required for detecting traces of œstrogens on paper chromatograms of blood extracts. (Œstrogens have an absorption maximum near 280 mµ, and light near this wave-length gives maximum contrast when used for photographing them on filter paper. The mercury-vapour lamp is commonly used for this purpose, but its emission in this region is weak and a train of filters is required.

THE timing of publication of Lord Hankey's books is masterly. The publication of his Lees Knowles Lecture fast year synchronized with debates on science and national defence in the light of the implications of atomic warfare. “Diplomacy by Conference” now appears almost simultaneously with a new White Paper, “Control Organisation for Defence”, which gives expression to many ideas advocated by Lord Hankey in both books. The title, however, gives no indication that this new volume, like the first, is a contribution to the whole theory and practice of government under the searching demands not only of war but also of peace. The book is, as the sub-title indicates, a series of studies in public affairs, lucidly and vividly presented, and of profound interest to the ordinary citizen as to the historian or statesman. From the first, to which the book owes its title, to the last which looks to the future control of external affairs, they are illumined by shrewd comment, keen observation and a human touch, and should go far to assist in the formation of a sound opinion on the working of the United Nations Organisation, the machinery or organisation for defence or the reform of the Foreign Service. Diplomacy by conference, Lord Hankey believes, has come to stay, and his personal experience leads him to regard elasticity of procedure, small numbers, informality, mutual acquaintance, if not personal friendship among the principals, a proper perspective between secrecy in deliberation and, publicity in results, reliable secretaries and interpreters as the most important factors in success, and which are the more essential the more delicate the subjects. Diplomacy by Conference Studies in Public Affairs 1920–1946. By the Rt. Hon. Lord Hankey. Pp. 180. (London: Ernest Benn, Ltd., 1946.) 12s. 6d. net.

THE name of Frank Schlesinger will always be associated with the determination of stellar parallaxes, for to him is mainly due the considerable knowledge of stellar distances that we now have. It was a fortunate circumstance that his postgraduate research was carried out at the Columbia University, where at the close of the nineteenth century astronomical research work was mainly concerned with the problems of the accurate determination of star positions by means of photography. The great possibilities that photography offered in this field were just beginning to be realized. Schlesinger's thesis for the Ph.D. degree was concerned with the accurate measurement and reduction of photographs of the Praesepe cluster, obtained by Rutherfurd, and showed originality of mind, a thorough grasp of fundamental principles, and ingenuity of method. He was quick to see the possibilities that photography offered for the accurate determination of stellar parallaxes. A short paper, published in 1899, entitled “Suggestions for the Determination of Stellar Parallax by means of Photography”, referred to the neglect of this important subject and estimated that not more than twenty-five or thirty stars had known parallaxes which could be relied on to within 0-05". It outlined methods which Schlesinger was himself afterwards to develop, and showed that he already clearly saw the main precautions that were needed to obtain accuracy.

DURING investigations into the carbohydrases of insects1 in the winter of 1957–58 it was found that the macerated tissue of the dormant larvae of the wood-boring insect of the species Melandrya striata, found in felled wood of Salix amygdaloides Anderss., contained a considerable proportion of glycerol as revealed by paper chromatography. This preliminary observation indicated that glycerol might be acting as an ‘anti-freeze’,2 a view supported by the observation that the larvae and the adult insects of M. striata did not contain glycerol during summer.

A North African grasshopper (Poekilocerus bufonius (Klug 1882) (Pyrgomorphidae)), with warning coloration and which feeds on milkweeds (Asclepiadaceae), contains cardenolides similar to those found in the plant. These heart poisons which, like digitalis, excite nausea and vomiting are found in the insect's body tissues and can also be ejected in solution from its defensive glands. They thus form part of the grasshopper's defence mechanisms.

WATERBORNE wastes from the fermentation industries are difficult to differentiate from natural biological metabolites that occur in streams. Detection of characteristic antigens from organisms would serve to identify such wastes as contributors to the pollution of streams. A study was undertaken to determine if sufficient antigenic material for detection was produced in the medium during fermentation and if the antigens were sufficiently stable to permit recovery and identification in microgram amounts.

WEGENER'S speculations have attracted so much attention that there must be many who would be glad to find some simple means of testing his fittings and coincidences for themselves. Owing to the distortion present in all maps such tests must be carried out on a globe. Wegener himself uses tracing paper, which must be cut and slashed in order that it may even approximately fit the surface; and any one who has tried it will admit that it is difficult to obtain satisfactory results. An easier plan is to roll out a lump of modelling wax or plasticine into a sheet of moderate thickness. The sheet may then be pressed upon the globe and cut to the required shape. According to my own experience, the best method is to cut the sheet a little smaller than the area that is to be represented, so that the actual margin appears all round it, and to build it outwards to this margin by the addition of small pieces of wax. Old plasticine which has become rather dry works very well and does not stick to the globe.

PROLONGED cooking in a strong solution of soap is a much more satisfactory method of cleaning these interesting objects than the commonly recommended method with caustic potash. The plan which I have tried with success is to place the materials in the soap solution in a small phial, which is enclosed in a sand-bath, and then left on a hot part of the kitchen range. In a few hours all the surrounding, tissues, or even the whole of the rest of the animal, is as completely disintegrated as it would be with the liquor potassae method, and the teeth all stand out bright and clear, but there is not the same risk of the so-called “palate” becoming disintegrated or curling up and becoming brittle.

Introduction. IN a paper published in the Philosophical Magazine for August 1899, I gave an account of some experiments on the photography of sound-waves, and their application in the teaching of optical phenomena. Since writing this paper I have extended the work somewhat and at a meeting of the Royal Society on February 15, 1900, gave an account of this work, and demonstrated certain features of wave motion with the cinematograph.

THERE are about 8,000 monumental brasses in the churches of Britain, representing only a small proportion of the total number of brasses set in place between about 1250 and 1650 (ref. 1). The preparation of rubbings of many of these brasses is extensively practised at present, particularly by visitors to England. Although brass rubbing (in the Netherlands) is documented as far back as 1656, the use of a wax crayon on paper has been popular in Britain only since the early nineteenth century2. Thus, when viewed in historical perspective, the increasingly popular brass rubbing activity must be considered as a comparatively new feature in the history of the monumental brasses. Our study was undertaken to determine whether repeated brass rubbing over periods of the order of a century will result in significant brass wear caused by the friction of the back of brass rubbing paper against the brass.

AMONG the Indian land mollusca the family Cyclophoridae especially attracts attention by the beauty of form and variety in the shells. The range is extensive, and their study began so far back as 1849, when W. H. Benson, of the Bengal Civil Service, and Capt. T. Hutton were writing on the animal of Diplommatina. After seventy years the above families are still very imperfectly understood, so little is known of the animal which constructs the shell. I think I am correct in saying the time had not arrived for publishing a volume on these molluscs, for sufficient material had not been examined; in truth, much has yet to be collected. It would be interesting to know for this reason why Mr. Gude was selected to do it, and the work then left to all intents and purposes completely in his hands; why malacologists with knowledge of the subject were not consulted; and why the present writer, with more than forty years' connection with these land operculates, both in the field and in collections, was in complete ignorance that such a work was under compilation. It leads me to think of past workers in this field of natural history. The foremost among them was the late Dr. William Blanford, the editor and founder of “The Fauna of British India.” No one would have known better how much preliminary work there was to do, or what material to obtain; and had he lived he would have prepared the way for it, as he did for vol. 1 of the Mollusca Series (the Testacellidae and Zonitidae). It recalls the type of paper he wrote on the animals of Raphaulus, Spiraculum, and other tube-bearing Cyclostomacea so long ago as 1863 in “The Annals and Magazine of Natural History.” There is even now food for thought in this paper, while it is an indication of how the history of the land operculates should be approached, which is to be looked for in vain in the publication under notice. The Fauna of British India, including Ceylon and Burma: Mollusca.—III. Land Operculates. (Cyclophoridae, Truncatellidae, Assimineidae, Helicinidae.) By G. K. Gude. Pp. xiv + 386. (London: Taylor and Francis; Calcutta: Thacker, Spink, and Co.; Bombay: Thacker and Co., Ltd., 1921.) 35s.

I HAVE recently employed a simple device for giving to an audience a vivid idea of an aurora, and that has been to paint a representation of it with Balmain's luminous paint. When dry the drawing may be hung up in the lecture-hall and covered with black tissue-paper until required. At the appointed time the lights are lowered, the tissue-paper withdrawn, and magnesium wire burnt in front of the painting. I had last week the pleasure of showing this to an audience of 500 persons, and from the expressions of curiosity and approval found it to be a very taking experiment.

THE liberal spirit in which the laboratory of the Royal College of Physicians of Edinburgh is thrown open to workers in every department of biology that bears, however remotely, upon medicine is worthy of the highest praise. That the opportunity for research thus afforded has been appreciated is well shown by this record of the work done in the laboratory during the second year of its existence. Sixteen papers are included in the volume, many of them anatomical and gynaecological, some pathological, one morphological (on the stomach of the Narwhal), and others (while including the results of studies in the laboratory) in the main clinical. This very diversity renders criticism difficult. Taking a high critical standpoint and employing as a standard the volumes which emanate from laboratories devoted to one subject—the Reports of the Physiological Laboratory of University College, London, or the studies from the Biological Laboratories of Cambridge or of Owens College, for example—it would be easy to find fault, to indicate papers that ought scarcely to be included, and to discover the absence of any series of allied researches of high scientific value, such as might be expected to be turned out in some special field of work, were the laboratory already long established, and were it given up to one branch of science, rather than intended from the first to be of use for investigations in all branches of biology. Yet to judge the volume from such a standpoint would be unfair both to the promoters of the laboratory and to those working within it. Taking medicine alone—that is to say, as apart from surgery and gynae cology—its extent is so considerable, and the topics dealt with so varied, that all original investigations, even if of equally high practical value, cannot be of equal scientific import: when surgery and gynaecology are also included, it is yet more obvious that much of the work that is rightly performed in the laboratory, while capable of almost immediate application to clinical practice, will be of a nature that does not necessarily call for great powers of original research. Clinical importance equally with scientific value must determine the inclusion of articles in such a volume as this. Herein, indeed, lies the only valid criticism that can be directed against these reports: if they be published purely as evidence of the activity of the laboratory, they well fulfil their purpose; but it is a little difficult to see what other use they possess. From the very diversity of the investigations, the reports cannot be expected to rank as useful additions to the library of the specialist in any of the subjects treated; there is too much extraneous matter. The gynaecologist will reap little benefit from the latter half of the volume, the pathologist will fail to appreciate the niceties of frozen sections of the lower portion of the body, cut in different planes. If such reports are to be of value to other workers, rather than, as I have said, as evidence of activity, they must be issued in separate parts, and, what is of still greater importance, they must assuredly not be issued at regular intervals. Successful as the laboratory has been up to the present, it is impossible to manufacture always a definite quantity of original work per annum and to order, and if it is intended to publish so many hundred pages at the expiration of every year, then it is only to be expected that many of those pages will either be work not of the highest quality, or will be upon subjects incompletely matured. Reports from the Laboratory of the Royal College of Physicians, Edinburgh. Vol. II. (Edinburgh and London: Young J. Pentland, 1890.)

IN NATURE, No. 150, p.393, a letter from Mr. G. C. Thompson is headed “Correlation of Colour and Music.” As this letter refers to a paper of mine published some time ago, permit me just to say that Mr. Justice Grove has in your journal objected to the use of the word “correlation” employed in this sense. Entirely coinciding with the opinion of the eminent parent of this work, I wrote as follows in NATURE for February 17, 1870:—“Analogy is certainly far more appropriate to express what is merely a parallelism, and not a necessary or complementary relationship between light and sound.” In the subsequent letter on this subject you adopted the word “analogy;” pardon, therefore, my pointing out an obviously accidental “reversion to the primitive type” which appeared in your paper Sept. 12.

(1) OF the twelve papers and symposia collected in the Proceedings of the Aristotelian Society for the last session, four are direct criticisms of positions taken up by Mr. Bertrand Russell. In the inaugural address on “ Science and Philosophy,” Dr. Bosanquet criticises the view, maintained in Mr. Russell's recent Lowell Lectures, that philosophy, as the science which aims at stating all that can be known A priori about all possible worlds, should be ethically neutral, and that it is just because philosophy in the past has been biased by the desire for agreeable conclusions that philosophy has not made the same progress as the physical sciences. Dr. Bosanquet holds that this view implies an antecedent limitation of philosophy, and involves “the confusion that because the interest of philosophy is purely theoretical, therefore its subject-matter is itself theory and its objects. (1) Proceedings of the Aristotelian Society. New series, vol. xv., containing the papers read before the Society during the Thirty-sixth Session, 1914â“1915. Pp. 441. (London: Williams, and Norgate, 1915.) Price 10s. 6d. net. (2) Selections from the Scottish Philosophy of Common Sense. Edited by G. A. Johnston. Pp. vii + 267. (Chicago and London: The Open Court Co., 1915.) Price 3s. 6d. net.

CONTROVERSY is commonly interesting, if only for the fact that it appeals to a man's pugnacious instincts; and most readers like to be invited to take sides. Eight of the eleven papers in this book were originally lectures, and in most of them Dr. Marett argues vigorously against what he regards as a lifeless manner of attacking the problems of folk-lore. He states his position in the first paper, and stands by it staunchly all through the volume. To him it is perfectly clear that every scrap of folk material is ultimately due to the more or less primitive reactions of the individual mind. Now nobody can understand either the productions or the modes of operation of the human spirit, he believes, by merely looking at them from the outside. The prime problem of all folk-lore is to enter into a man's thoughts, fancies, and emotions when he is confronted by certain definable situations. But simply to study objectively the changes which folk material has undergone in the course of its history is only to gather together a lot of dry bones. The psychologist is needed to put flesh on them, and to breathe into them the breath of life. Dr. W. H. R. Rivers is thereupon, in the most pleasant manner possible, held up as an awful example of the soulless sociologist. Psychology and Folk-lore. By Dr. R. R. Marett. Pp, ix + 275. (London: Methuen and Co., Ltd., 1920.) Price 7s. 6d. net.

THE great map of the veteran Sir Richard Griffith, followed by the detailed labours of other geologists, especially of the Geological Survey, and of its lamented director, the late J. B. Jukes, has explained the general geological structure of Ireland, and sketched, partly in outline, partly in considerable detail, the curious problems which that structure suggests. As yet, however, the abundant published information to be gleaned from papers and memoirs regarding Irish geology lies chiefly scattered through the Transactions of various scientific societies, and the Explanations of the Survey. Some of these publications are not nearly so widely known as they deserve to be, or as they assuredly would be if it were more easy for geological students in general to procure a reading of them. Mr. Hull has, therefore, done good service in preparing this little handbook to the geology and geography of Ireland. It is a most useful compendium of information, and its utility is greatly enhanced by the references to those works and papers where the subjects he discusses are more fully treated. The Physical Geology and Geography of Ireland. By Edward Hull (London: Stanford, 1878.)

DR. INGLEBY is curious to know what Prof. Helmholtz would say on this vexed question. If Dr. Ingleby will turn to page 630 of the “Physiologische Optik,” he will find that Prof. Helmholtz has anticipated his wishes. As others of your readers may be interested in seeing how the matter is treated by one who is facile princeps in this department, I subjoin a translation of the passage. If the curious experiment mentioned by Dr. Ingleby had referred only to the vertical diameter of the disc, it would have seemed to be another illustration of our inveterate tendency to ascribe an exaggerated value to vertical lines or angles, at or near the horizon. It is said that if ten men be required to fix off-hand on a star half way between the zenith and horizon, nine, at least, will choose one very much too low. If an exact square be cut out in paper and pinned against the wall opposite to the eye, the sides will appear longer than the top or bottom. If an equilateral triangle be placed in the same position, the angles at the base will appear larger than the angle at the vertex. If a line be drawn parallel to the bottom of a sheet of paper, and a second line, making with it an angle of 20° or 30°, any one attempting, without moving the paper, to draw a third line through the point of intersection, so as to make an angle with the second line equal to that which the second makes with the first, will make the second angle too large. (This experiment is guaranteed by Helmholtz.) After reading Helmholtz's theory, metaphysicians may be willing to allow that all these illusions are to be derived, after his example, from the clouds. As metaphysicians have, before now, contributed a good deal to the clouds, it is perhaps only fair that the clouds should contribute something to the metaphysicians.

UPON reading Dr. Pole's two papers (NATURE, vol. xviii. pp. 676, 700) my first feeling was to ask: “But how could ‘The blind old man of Scio's rocky isle’ know anything at all about colour?” Presuming, however, that the tradition of his blindness might be unwarranted, and further, that it may be a mistake to suppose, as many do, that the “Iliad” is a collection of rhapsodies by different poets, I again asked myself: “Are there in Homer more anomalies in the nomenclature of colours than may be accounted for by the vague use of words? Are there more than we should find in this country among uneducated men of the labouring class?” About two years ago I made extensive inquiry as to the prevalence of colour-blindness among children, and in the village schools of this part of Somersetshire I found that the girls could name the neutral as well as the other tints readily and correctly, but that many of the boys had but about half-a-dozen words to use, and would refer orange to red or to yellow, and purple to brown or to blue, merely for want of terms; for they could match the test papers with other papers, or with the girls’ dresses.

AFTER the Revolution in Russia in 1917, the United States Government severed diplomatic relations and did not resume them until 1933. To commemorate the ten-year period a meeting of the Science Panel of the Congress of American-Soviet Friendship was held in New York City on November 7, 1943. It was in two parts: one section under Prof. Harold C. Urey dealt with Soviet science and technology, and the other under Prof. Walter B. Cannon with public health and war-time medicine in the U.S.S.R. Fourteen papers were read, each dealing with a particular branch of science, and they are collected in this little volume, "Science in Soviet Russia". Science in Soviet Russia Papers presented at Congress of American-Soviet Friendship, New York City, November 7, 1943, under the auspices of the National Council of American-Soviet Friendship. Pp. ix + 7. (Lancaster, Pa.: Jaques Cattell Press, 1944.) 1.50 dollars.

THE explanation of the discrepancy between Prof. Allman's and my own citation of my article in NATURE, vol. xxii. p, 147, appears to be that Prof. Allman has unfortunately received a copy of NATURE differing from the majority of the issue of that date in the fact that it was printed off before the final corrections, sent to the office of NATURE on Wednesday, had been inserted. These corrections were made before the greater number of the issue was struck off, and I have only just ascertained, to my great surprise, that any of the unconnected copies had been circulated. The error as to the marginal canal was also present in the proof of my paper, marked “uncorrected proof, confidential,” which was circulated among the Fellows at the meeting of the Royal Society on June 17, but the error was corrected by me before the reading of the paper.

THE new ‘Unified Field-Theory’ of Einstein is contained in two papers amounting altogether to eleven pages in the Berlin Sitzungsberichte, 17, 1928, and 1, 1929. There is an intermediate paper which does not concern us, since it follows a line of development now abandoned. For the present, at any rate, a non-mathematical explanation is out of the question, and in any case would miss the main purpose of the theory, which is to weld a number of laws into a mathematical expression of formal simplicity. We are chiefly interested in how it compares, both as to methods and results, with the existing field-theories which have had some measure of success.