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photometric observations extend the observations of Z Draconis over nearly 7000 periods and of RT Persei over nearly 11,000 periods. Visual and photographic light-curves were compared.

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R. J. McDiarmid : The Variable Stars TV, TW, and TX Cassiopeia."

A brief discussion of the light-curves of the variable stars TV, TW, TX Cassiopeia and T Leonis Minoris was given, pointing out interesting features in connection with each system. In the system TV Cass. we have two stars of nearly the same size but of different surface brightness, the ratio being 5.5 to 1.0. In this system other points of interest are brought out, such as the reflection and ellipticity effects. The system TW Cass. represents two stars of almost equal brightness and of nearly the same size, moving in an eccentric orbit. In the third system TX Cass. the two stars are very unequal in size with a ratio of surface brightness of 10 to 15. The stars are ellipsoidal in shape, giving rise to an ellipticity effect shown by the light-curve. The system is of special interest, as there seems to be little doubt of its being similar to the sun, bright at the centre, decreasing in brightness towards the limb. T Leonis Minoris is an eclipsing variable. The ratio of the surface of the two stars in the eclipsing system T. Leonis Minoris is 1 to 25. Dr. Edwin B. Frost : Orion Nebula."

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Radial Velocities in the

The investigations of the nebula in Orion by Messrs. Bourget, Fabry, and Buisson, of Marseilles, published in the Astrophysical Journal for October, 1914, show that the photographic interferometer method can be applied successfully to the study of the radial velocities of the nebula, both as a whole and in its separate parts. Their conclusion that there are appreciable motions in closely adjacent portions of the nebula have been confirmed by observations made recently with the Bruce spectrograph. Differences of more than 10 km. per second in the velocity in the line of sight have been found, and the general effect of rotation of the nebula inferred by the French observers is confirmed by the spectrograph.



BIRMINGHAM. The council has decided that in the existing circumstances of national stress the ordinary annual degree congregation with its attendant ceremonial and festivity would be inappropriate. All degrees this year will therefore be granted in absentia.

Dr. T. Sydney Short has been appointed Ingleby lecturer for 1916, and Dr. Douglas Stanley has been appointed honorary examiner for the Russell Memorial Prize for the current year.

THE Board of Trinity College, Dublin, has appointed Miss E. M. Maxwell, of the Royal Victoria Eye and Ear Hospital, Dublin, to the Montgomery lectureship in ophthalmology, the establishment of which was announced in NATURE of February 25 last.

We have received from Washington a copy of the report of the librarian of Congress and of the superintendent of the library building and grounds for the financial year ending June 30, 1914. It is interesting to note that in 1897 the library comprised about 850,000 printed volumes and pamphlets and about 500,000 other articles-manuscripts, maps, and prints; and a staff of forty-two persons. The grants for the purchase of books was 6000l. a year, and for printing and binding 5000l. At the date of the report the

grant for the purchase of books had increased to 20,000l., the staff in the library proper was 385, and the number of books had reached two millions, and the other articles another million. In other words, the collection is now in size third among those of the world. We have also received from the Library of Congress a catalogue of the publications issued by the library since 1897.



Royal Society, June 3.-Sir William Crookes, president, in the chair.-Prof. C. H. Lees: The shapes of the equipotential surfaces in the air near long buildings or walls, and their effect on the measurement of atmospheric potential gradients. The shapes of the equipotential surfaces are determined, and the equipotential lines drawn to scale in the following cases: (1) A thin vertical wall; (2) a retaining wall separating a lower from a higher horizontal plane; (3) a series of equidistant parallel vertical walls. In each case the normal vertical potential gradient may be calculated. from observations of the potential at any point. A point on each wall is indicated at which the horizontal potential gradient is identical with the normal vertical gradient.-Prof. O. W. Richardson: The influence of gases on the emission of electrons and ions from hot metals. As is well known, the thermionic saturation current is expressed accurately and quite generally over wide ranges of temperature by the equation i=ATle-b/T. In the case of metals, in particular, the equation is satisfied when the metals are contaminated by the presence of a gaseous atmosphere, as well as when the surfaces of the pure metals are tested. In general, however, the effect of the contaminating gas is to cause large changes in the values of the constants A and b. The changes which are thus brought about in these constants are considered in the present paper. So far as it may be considered trustworthy, the available evidence shows that A and b for a given metal always change together in such a way that the change in log A is proportional to the change in b. This linear relation is very closely satisfied by the results of all Langmuir's observations with tungsten, for which substance different gases change A by as large a factor as 102. A similar relation, with an almost equal coefficient of proportionality, is required by the best observations on the negative emission from platinum. In the case of tungsten, contaminants cause an increase in A and b, whereas with platinum a diminution occurs. All the known data point to the existence of a similar law governing the steady emission of positive ions from platinum. By applying thermodynamic considerations to the emission of electrons from contaminated surfaces, it is shown to follow from the linear relation between log A and b, that the contact potential difference between the pure and the contaminated metal is of the form a(1-aT), where the constant a, has opposite signs for tungsten and platinum, and a has approximately the same value for both metals. T is the absolute temperature.-Prof. J. W. Nicholson: The band spectrum associated with helium. Fowler has concluded recently that the heads of the bands in the new spectrum associated with, and perhaps due to, helium follow laws of the type hitherto peculiar to line-series. A further examination of some points which were in doubt has been made with the following results:-(1) The paper supports the conclusion that the heads of the bands in the spectrum of Goldstein and Curtis follow ordinary series laws by showing that the doublet separations actually tend to zero at the limits of the series; (2) both the doublet

series isolated by Fowler are strictly analogous to principal series in line-spectra; (3) the generalised Rydberg formula, in which the wave number is a function of m+u, gives the most suitable representation of these series as well as of line-series.-C. Dobell and A. P. Jameson: The chromosome cycle in Coccidia and Gregarines. The authors have investigated the chromosomes of a coccidian (Aggregata eberthi) and a gregarine (Diplocystis schneideri). They have found that the chromosomes are present in the haploid (“reduced") number-six in Aggregata, three in Diplocystis at every nuclear division in the life-history except that of the zygote nucleus. This nucleus contains the diploid number of chromosomes-twelve in Aggregata, six in Diplocystis-and its division is a reduction division which halves the chromosome number. Reduction thus occurs in these organisms immediately after fertilisation, and not during gametogenesis.

Mathematical Society, June 10.-Sir Joseph Larmor, president, in the chair.-Prof. W. Burnside: Periodic irrotational waves at the surface of deep water.-Prof. M. Kuniyeda: A theorem on series of orthogonal functions.-G. R. Goldsbrough: The effect on the tides of the variation in the depth of the sea.-Prof. D. Buchanan: Oscillations near an isosceles triangle solution of the problem of three bodies, as the finite masses become unequal.


LINNEAN SOCIETY, at 5.-Colonel Montagu, Naturalist: Bruce Cummings. -The Fibre of Calotrobis procera, and the Cultivation of the Plant from an Economic Point of View: Dr. George Henderson.-The Structure of the Rhizopod Test: John Hopkinson. Medusa from the Indian Ocean, collected in 1905: E. T. Browne.-Report on the Hexactinellid Sponges (Triaxonida) collected by H.M.S. Sealark in the Indian Ocean: Prof. A. Dendy. The Cephalopoda obtained by the Percy Sladen Trust Expedition to the Indian Ocean in 1905: J. C. Robson.

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Pp. 362.

The Names of Physical Units. Dr. Ch. Ed. Guillaume; Dr. J. A. Harker, F.R.S. University Appointments in War Time.-Prof. Percy F. Frankland, F.R.S.

Galileo and the Principle of Similitude.-Prof. D'Arcy W. Thompson, C.B.






The General Theory of Dirichlet's Series. G. H. Hardy and Dr. M. Riesz. Pp. 78. (Cambridge At the University Press.) 3s. 6d. net. The Soul of the War. By P. Gibbs. (London: W. Heinemann.) Ios. 6d. net. Elementary Experimental Statics. By I. B. Hart. Pp. vii+200. (London: J. M. Dent and Sons, Ltd.) 2s. 6d.

The People of India. By Sir H. Risley. Second edition. Edited by W. Crooke. Pp. xxxii+472+ plates XXXV. (Calcutta Thacker, Spink and Co.; London: W. Thacker and Co.) 21s. net.

Making the Most of Life. By Prof. M. V. O'Shea and J. H. Kellogg. Pp. ix + 298. (New York: The Macmillan Company; London: Macmillan and Co., Ltd.) 3s. 6d.

The Statesman's Year-Book, 1915. Edited by Dr. J. Scott Keltie, assisted by Dr. M. Epstein. Pp. lxxxiv + 1536. (London: Macmillan and Co., Ltd.)

IOS. 6d. net.

Petroleum Technologist's Pocket-Book. By Sir B. Redwood and A. W. Eastlake. Pp. xxiv + 454. (London: C. Griffin and Co., Ltd.) 8s. 6d. net.

Refuse Disposal. By Prof. E. R. Matthews. Pp. xiii+160. (London: C. Griffin and Co., Ltd.) 6s.


The Tokyo Imperial University Calendar, 1913-14. Pp. vi+ 349. (Tokyo: Maruya and Co.)



ROVAL SOCIETY, at 4.30.-Analyses of Agricu'tural Yield. II. The Sowing-date Experin.ent with Egyptian Cotton, 1913: W. L. Balls and F. S. Holton.-Soil Protozoa and Soil Bacteria: E. J. Russell.The Enhanced Series of Lines in Spectra of the Alkaline Earths: Prof. W. M. Hicks-Certain Linear Differential Equations of Astronomical Interest: Prof. H. F. Baker.-The Partial Correlation-Ratio: Prof. Karl Pearson.-The Effect of Temperature on the Hissing of Water when flowing through a Constricted Tube: S. Skinner and F. Entwistle.Ionisation Potentials of Mercury Cadmium and Zinc and the Single and Many-lined Spectra of these Elements: J. C. McLennan and J. P. Henderson.-A Diagram to Facilitate the Study of External Ballistics : Prof. W. E. Dalby.-The Monoclinic Sulphates containing Ammonium. Completion of the Double Sulphate Series: Dr. A. E. H. Tutton.-And other papers.

Volunteers for Scientific Work.-Edward Heron.

Scientific Methods in Industry. By W. P. Dreaper 428
Hampshire Field Archæology. (Illustrated.) By
Lieut. W. E. Rolston

Cotton for German Ammunition. By Sir William
Ramsay, K. C. B., F. R. S.
Mr. F. H. Neville, F.R. S.

Our Astronomical Column:


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The title is, however, unintentionally misleading. Although it is called a practical handbook, the term does not imply any technical details of production, such as one finds in the volumes of Sir Boverton Redwood. It is concerned only with the chemistry of the subject-that is to say, its theoretical side-and such simple practical experiments and tests as can be performed in a laboratory. Moreover, "the substitutes " monopolise a large share of the volume. For example, the descriptive portion of the petroleum industry occupies less than one-twentieth of the total number of pages, and about the same amount of space is accorded to the distillation of bituminous shale, of coal, and of coal-tar, and to the production of ethyl alcohol and wood spirit, whilst tests of various kinds, including the determination of physical constants and a few simple organic preparations, fill up the rest of the volume.

The book is actually a treatise on the chemistry and valuation of liquid fuels, and is intended to serve as a text-book for a part of the curriculum which, together with the course on petroleum mining, forms one of the subjects for the diploma or B.Sc. degree of the University of Birmingham.

Having briefly indicated the scope and object of the book, we can only express our full agreement with the writer of the introduction (Sir B. Redwood) that, in providing a text-book for students who desire to become proficient in the chemical technology of petroleum, the authors properly consider that no man can become a successful technologist until he has fully mastered the underlying scientific principles of the subject.

There is no doubt that, at the present time, when such large quantities of liquid fuel are used for motive power and where so much ignorance of the methods of estimating the value of these substances prevails, a book of this character, the aim of which is to teach technical methods of analysis, ought to, and no doubt will, command general interest. If we have one criticism to offer

it is that an attempt has been made to combine the study of organic chemistry with that of technology. The whole range of organic chemistry is run through in the first 62 pages, followed at intervals by the description of a few substances which the student is supposed to prepare in the laboratory.

As a preparation for the future expert technologist in so complex and so important a branch as the chemistry of liquid fuel, we should consider this wholly inadequate, and that a substantial course of theoretical and practical organic chemistry ought to precede its applications. Apart from this, we can cordially commend the volume and the excellence of the information it. contains. J. B. C.


The Evolution of Sex in Plants. By J. M. Coulter.
Pp. ix+140. (Chicago: University of Chicago
Press; London: At the Cambridge University
Press, 1914.) Price 4s. net.


OROF. COULTER gives a luminous sketch of the probable history of sexual reproduction in plants. He deals with the origin of pairing gametes from spores, with the differentiation of (1) eggs and sperms, (2) specialised sex organs, and (3) sexual individuals (such as the male and female gametophytes of Equisetum), and with the special problems of alternation of generations and parthenogenesis. In the case of plants it is plain that the function of sex is not to secure reproduction, but to secure something in connection with reproduction which is not attained by the asexual methods. The sexual method is added on to the older asexual methods, and does not replace them. Before sexual reproduction was established there were three stages:--The primal capacity for celldivision led on to spore-formation by vegetative cells, and that to spore-formation by special cells.

The origin of sex was marked by the appearance of minute, motile gametes-reproductive cells that pair and fuse. If the material of a protoplast is divided only a few times there is spore-formation; if the divisions are more numerous the cells produced are probably gametes. Perhaps the ageing of cells stimulates the numerous divisions and the production of cells incapable of functioning as spores. Whether the pairing gametes appear similar (isogamy) or dissimilar (heterogamy) there is certainly physiological unlikeness. They are the bearers of sex-determiners and corresponding sex-inhibitors, which are passed on through generations of vegetative cells until conditions favour their expression in

gamete-formation again. It is a mistake to suppose that nutrition determines sexuality, but it sometimes determines the opportunity for the expression of sexuality. Similarly, the nutritive supply is not necessarily related to differentiation of sex or size. The male gametophyte of Equisetum is small because it is a male, and not male because it is small.

The general theory suggested in this interesting essay is that decline of vegetative vigour favours the production of gametes with characteristic chemical substances. The zygotes that result from the pairing of gametes tend to lie dormant until environmental conditions improve-a useful and probably primary protective adaptation. The peculiarity of gametes is not to be found in their motility, or in their minuteness, or even in pairing (as is shown by nuclear fusions in endospermformation); what, then, is their essential feature? In the reduction division their nuclei become peculiar, so that a new individual can only be produced after the nuclei have fused. advantage of this is probably in securing individuality or variation. Thus sexual reproduction makes, on the one hand, for protection, and, on the other, for variability.


(1) La Cémentation de L'Acier. By Prof. F. Giolitti. Traduction française revue par M. A. Portevin. Pp. 548. (Paris: A. Hermann et Fils, 1914.) Price 16 francs.

(2) The Case-hardening of Steel. By H. Brearley. Pp. xv+164. (London: Iliffe and Sons, Ltd., 1914.) Price 7s. 6d.

(1) PRO

OROF. GIOLITTI is probably the greatest living authority on the cementation of steel, and in the above-mentioned publication will be found by far the most comprehensive and lucid presentation of this subject that has ever appeared. During recent years many important original researches in this domain have been published by him and his co-workers at Turin, and no one is better qualified than he to summarise present-day knowledge with regard to it. M. Portevin, in rendering as he has done an admirable French translation of the Italian text, has considerably enlarged the circle of students to whom the book will be available.

As Prof. Giolitti remarks in his preface, there is probably no branch of present-day steel tech nology in which empiricism is so supreme as cementation or case-hardening. Such a condition of things, justifiable no doubt at one time, can no longer be defended. Scientific knowledge is now available which permits this highly important

process to be carried out under simple and easily controlled conditions with inexpensive materials, in such a way as to secure definite results with remarkable certitude. In spite of this, many works are content to go on buying at fancy prices mixtures of a very ordinary character, the nature of which is entirely disguised by the trade names under which they are sold.

. Part i. of the book deals with cementation processes from a chemical point of view, and consists of five chapters, which trace the sequence of researches that laid the foundation of scientific casehardening, and gradually lead up to the final chapter on present-day knowledge of the subject. The author The author has been exceedingly careful in mastering and summarising the literature available, and in spite of his own large share of the experimental field he seems to have missed little or nothing that anybody else has done. It seems now to be well established that while pure carbon can and does under suitable conditions of heating carburise solid iron in the complete absence of any gas, yet such carburisation proceeds so slowly as to be useless from the technical point of view. All industrial case-hardening processes require the presence of gas, and to the question "What are the respective parts played by the carbon and the gas in such processes?" it is impossible to return an answer that will hold for all cases. It is necessary to examine for every type of cementing material the specific action of the gas which may be formed, and then to study how this action is modified by the presence either of free carbon pre-existing in the cement or of carbon formed during cementation.

Part ii. deals with the technical applications of cementation, and of particular interest are the chapters relating to liquid and gaseous cementing agents. It is unfortunate that the table of contents is very meagre, and that the book is without an index. It is to be hoped that the latter defect will be remedied when a second edition appears, for it detracts considerably from the usefulness of the book in its present form.

(2) Mr. Brearley's book has been written mainly for those who are engaged in the commercial production of case-hardened objects. Nothing could indicate its point of view better than the following quotation from his preface: "An explanation based on the mechanical structure of an object is intelligible, because most minds can appreciate the elements of design and pass judg ment on the composite properties of materials. All kinds of steel have a mechanical structure which, when suitably magnified, is as obvious as that of reinforced concrete. It is in terms of such structures that the properties of case-hardened steels

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must be explained." Chapters i.-vii. are concerned with various aspects of case-hardening processes, and these are followed by others dealing with methods of testing, automobile steels, hardening and tempering, and finally surface hardening without cementation. No attempt is made to separate the subject into practical and theoretical divisions, and the author's treatment presupposes an elementary knowledge of metallography on the part of his readers.

In a book of this kind it is gratifying to find the following opinion (p. 77): "The most helpful of all generalisations in metallurgy is the one based on observations made with the pyrometer and confirmed by the microscope, known as the equilibrium diagram." Mr. Brearley is to be congratulated on the production of a book that was well worth writing, and one which should certainly be of use to those for whom it is intended. It will repay studying, moreover, by others than case-hardeners.



By L. H.

The Principles of Fruit-Growing. Bailey. Twentieth Edition. Pp. xiv +432. (New York: The Macmillan Co., London: Macmillan and Co., Ltd., 1915.) Price 7s. 6d. net.

THIS book has in its different editions been used for nearly eighteen years as a standard text-book on commercial fruit-growing, in the Agricultural and Horticultural Colleges of the U.S.A., Canada, and England.

For the present edition the work has been largely re-written; it deals with important subjects, such as the choice of locality and site; the setting out of orchards; the principles of vegetable physiology involved in the cultivation, pruning and thinning of the fruit, and so on. The question of manuring of orchards, based on experiments at the American Experiment Stations, gives clear general reasons for the effect or non-effect of the fertiliser. The phenomenon of self-sterility of varieties and the advantage of cross-pollination are discussed. Examples of score cards dealing with the growth and character of the tree as well as the fruit show that this is a valuable method for comparison of varieties; an example of a work sheet of an orchard, together with cost and return, show what may be advantageously learnt from keeping such a record. Cover crops and protection from frost by orchard heating are described; control of insect pests and fungoid diseases, and the choice of pumps and nozzles, are well treated; harvesting, packing, and fruit storage houses, also special points of interest such as the origin of varieties, are discussed.

The book is one to interest any English apple grower (it is the apple that is chiefly dealt with); it presents new aspects of things different from

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Infant Mortality. By Dr. H. T. Ashby. Pp. x+229. (Cambridge: At the University Press, 1915.) Price 10s. 6d. net.

THE appearance of Dr. Ashby's book is very well timed, for in these days of human wastage it behoves a nation to conserve its resources. It is true that in recent years there has been a slight drop in infant mortality, but it is still disgracefully high, and is largely counterbalanced by a fall in the birth-rate. The word disgraceful is the correct one, because the vast majority of deaths are due to preventable causes, of which the most important is diarrhoea due to bad feeding and especially to bad and infected milk. Dr. Ashby shows that much may be done by the proper instruction of the mothers, but by far the greatest responsibility falls on public bodies and the Government, for it is only they who can deal with the larger questions of hygienic precautions, such as regulations of cleanliness in food depots, and the prevention of fly-borne disease; the call for proper regulation of the milk traffic is an urgent one; the provision of shells is important, but the provision of a healthy race to make and use them is even more pressing. We trust that useful books such as the one under

consideration may bear fruit in the proper quarters.

W. D. H.

St. Bartholomew's Hospital in Peace and War. The Rede Lecture, 1915. By Dr. Norman Moore. Pp. 56 (Cambridge: At the University Press, 1915.) Price 2s. net.

WE welcome the publication of this Rede lecture delivered on May 6, 1915, in the Senate House, Cambridge, by Dr. Norman Moore. Such a charmingly written history of a great hospital will appeal to a wide circle of readers. As Dr. Moore says, the history shows "how in a free country such as ours, where everything is not dominated by Government, an ancient institution like St. Bartholomew's Hospital, whether in peace or war, lives with the nation and is in touch with the national life in every period."

Educative Geography. A Note-book for Teachers. By J. L. Haddon. Pp. 76 (London: G. W. Bacon and Co., Ltd., 1915.) Price 1s. net. IT is to be hoped that this little book may secure a wide circulation among teachers of geography in elementary schools and the junior classes of secondary schools. It should convince all who read it that lessons in geography become both more valuable and interesting when they include simple practical exercises to be worked by the children themselves, and that the provision of such work is neither expensive nor unduly troublesome.

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