Imagens das páginas

L. E. Cox. Pp. vii+111. (London: Longmans and
Co.) 25. net.
Union of South Africa. Department of Agriculture.
Report with Appendices for the Year, April 1, 1913, to

March 31, 1914. Pp. 299. (Cape Town: Cape

Times, Ltd.) 7s. 6d.

Zròdla Podświadomości i jej Przejawy. By E. Abramowski. Pp. 207 (Warszawa: Drukarnia Polska.) 1.50 kop.

Podstawy Naukowe Elektrotechniki Lacznie Ꮓ Zasadami Pomiarów, M. Pozaryski. Pp. x+415. (Warszawa: Gebethnera i. Wolffa.) 2.40 kop.

Institut Psychologiezny W Warszawie. Prace z Psychologii Dòswiadczalnej. Edited by E. Abramowskiego. Tom. ii. Pp. xii+362. (Warszawa: Gebethnera i. Wolffa.) 1.80 kop.

Zagadnienia dotyczace gieometrji Elementarnej zebral i Ulozyl F. Enriques. Tom. i. Pp. iv+331. (Warszawa: Gebethnera i. Wolffa.) 1.50 kop. Towarzystwo Naukowe Warszawskie. By Ė. Loth. Pp. v+71. (Warszawa: Gebethnera i. Wolffa.) 75 kop.

M. Faraday Dzieje Swiecy sześć wykladów popularnych W. Przekladzie Marji i. Stanislawa Kalinowskich. (Warszawa: Gebethnera i. Wolffa.) 50 kop.

Biblioteka Matematyczno - Fizyczna. Serva iii. x. Teorya Liczb (Kurs Uniwersytecki). Dr. W. Sierpinski. Pp. xiv +412. (Warszawa: Gebethnera i. Wolffa.) 1.80 kop.

The Limitations of Science. By Prof. L. T. More. Pp. 268. (New York: H. Holt and Co.) 1.50 dollars


Wisconsin Geological and Natural History Survey. Bulletin No. xxxiii. Scientific Series. No. 10.


Polyporaceæ of Wisconsin By J. J. Neuman. Pp. 206+ xxv plates. Bulletin No. xli. Economic Series. No. 18. A Study of Methods of Mine Valuation and Assessment, with Special Reference to the Zinc Mines of South-western Wisconsin. By W. J. Uglow. Pp. 73. (Madison, Wis.)

Surface Tension and Surface Energy and their Influence on Chemical Phenomena. By Dr. R. S. Willows and E. Hatschek. Pp. viii+80. (London: J. and A. Churchill.) 2s. 6d. net.

Plant Breeding. Bv L. H. Bailey. New edition. Revised by Dr. A. W. Gilbert. Pp. xviii+474. (New York: The Macmillan Co.; London: Macmillan and Co., Ltd.) 8s. 6d. net.

Royal Botanic Gardens, Kew. Hand-list of Tender Monocotyledons, excluding Orchidaceæ, cultivated in the Royal Botanic Gardens. Second edition. Pp. 241. (London: H.M.S.O.: Royal Gardens, Kew.) IS. 6d. The Book of the Fly. By G. H. Hardy. Pp. 124. (London: W. Heinemann.) 2s. 6d. net.



ROVAL SOCIETY, at 4.39.-The Shapes of the Equipotential Surfaces in the Air near Long Buildings or Walls, and their Effect on the Measurement of Atmospheric Potential Gradients Prof. C. H. Lees.-The Influence of Gases on the Emission of Electrons and Ions from Hot Metals: Prof. O. W. Richardson. -The Band Spectrum associated with Helium J. W. Nicholson.-Soil Protozoa and Soil Bacteria: E. J. Russell.-The Chromosome Cycle in Coccidia and Gregarines: C. Dobell and A. P. Jameson.

ROVAL INSTITUTION. at 3.-Methods of presenting Character in Biography and Fiction: Wilfrid Ward.

FRIDAY, JUNE 4. ROYAL INSTITUTION, at 9.-Radiations from Exploding Atoms: Sir E. Rutherford. GEOLOGISTS' ASSOCIATION (at University College). at 8.-Lakes and their Origin, with Special Reference to Rock-basins: Prof. E. J. Garwood. MONDAY, JUNE 7.

ROYAL INSTITUTION, at 3.-Method of Presenting Character in Biography and Fiction: Wilfrid Ward.

SOCIETY OF CHEMICAL INDUSTRY, at 8.-A New Process for the Refining of Chile Saltpetre: J. B. Hobsbaum.-A Method of Testing Mineral

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ROYAL INSTITUTION, at 3.-The Evolution of Steel-Influence on Civilisation Prof. J. O. Arnold. ZOOLOGICAL SOCIETY, at 5.30.-The Feet and Glands and other External Characters of the Paradoxurine Genera Paradoxurus, Artictis, Arctogalidia, and Nandinia: R. 1. Pocock.-The Skull of an Extinct Carnivore related to Aeluropus, from a Cavern in the Ruby Mines, Mogok, Burma : Dr. A. Smith Woodward.-The Early Development of the Heart and Anterior Vessels in Marsupials, with Special Reference to Perameles: Miss K. M. Parker.-The Triassic Stegocephalians, Brachyops, Bothriceps, and Lydekkerina, gen. nov.: Dr. K. Broom.

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THURSDAY, JUNE 10, 1915.

SCHOOL SCIENCE. Elements of General Science. By Dr. O. W. Caldwell and W. L. Eikenberry. Pp. xiv + 308. (London: Ginn and Co., n.d.) Price 4s. 6d.


N every school in this country there is found a small percentage of boys or girls who have a decided bent towards experiment of a thoughtful character coupled with a thirst for knowledge of natural phenomena. The science master who knows his business will speedily recognise such a boy and apply the appropriate treatment, which usually consists in the suggestion of extra problems to be worked out in the laboratory, and of extra reading, selected to fit the need of the moment and create further needs for future satisfaction. Guided, but not overhelped, these boys will soon be fit for enlistment as recruits to the army of scientific investigators. When framing the syllabus of the general science course of the school, there is no need to provide for the training of specialists. There is need, and very great need, to provide a course of science work for the average boy and girl which will (1) be in touch with everyday experience, (2) deal with matters of wide interest and importance, (3) give some appreciation of what scientific experiment means and of what scientific synthesis is capable. the end of the course, if the pupil wishes to know more and has acquired some power of satisfying that wish by his own efforts, if his attitude towards the opinions and labours of specialists is one of rational respect, the work may be pronounced a success.


The authors of the school-book under review have clearly had in mind the needs (1) and (2) stated above, as they have throughout dealt with live topics of major importance. The contents table of the book shows a richness in the quantity and quality of the topics-beginning with air and the barometer, and concluding with heredity and environment—which makes the ordinary syllabus of an English school appear poverty-stricken by comparison. Unfortunately, the third requisite for a satisfactory school course is not fulfilled there is nothing in this book which teaches the meaning of experiment, and consequently little hope that it will educe an appreciation of scientific method. The material accomplishments of applied science will not fail to be acknowledged; but of the human interest of investigation (apart from its results) and of the beauty of a universe lawful to its core, there is no revelation in these pages. Prof. C. H. Judd, of the University of

Chicago, in an Introduction" to the book, speaks of the "inhibition of science" in school organisation. Have we not in England also experienced some disappointment with the results of school science? A comparison of American and English methods suggests that their merits and defects are complementary, that while America still hustles her pupils through a pemmican meal of dogmatic information, England keeps hers practising the goose-step of "determining the density of the given solid." In neither country is there sufficient real experimenting, and proper correlation with mathematics, geography, workshop practice, and art is too often to seek English teachers might gain by pondering the valuable content of the lessons in this book; while we venture to hope that more regard for heuristic principles, even at some sacrifice of informationgetting, may help to remove "the inhibition of science" of which Prof. Judd complains.

G. F. D.

PRACTICAL PLANT PHYSIOLOGY. Ernährungsphysiologisches Praktikum der höheren Pflanzen. By Prof. V. Grafe. Pp. x+494. (Berlin P. Parey, 1914.) Price 17 marks.


HE books dealing with the practical side of advanced plant physiology are so few in number that any addition to them is very welcome. As the title indicates, Prof. Grafe's work deals only with the metabolic side of plant physiology, the phenomena included under the term irritability being excluded from the scope of the work. The book differs from all previous works on practical plant physiology in its size-it is a quarto volume of nearly five hundred pages-and also in its purpose, since it is designed mainly as a help in research work, rather than for teaching purposes as are the well-known works of Darwin and Acton, Detmer, and Ganong.

The author is well known for his chemical work in plant physiology, so, as we should expect, the biochemical aspect of the subject is the one that is most elaborated. He states in his preface that the book has arisen in response to the need for a guide in his own chemico-physiological practical work, and that it is meant to stand midway between such practical books as those already mentioned and Abderhalden's "Handbuch der Biochemischen Arbeitsmethoden." The work, however, is more than a mere practical book, for under many of the sections we find, besides a description of the methods to be used, also a statement of the results obtained by such methods.

The book deals first with the swelling of the seed and the effect of external conditions on ger

mination and on the growth of seedlings, including the methods of water culture. Then we have a section on ash-analysis and on carbon dioxide assimilation, which includes the qualitative and quantitative determination of the products of photosynthesis; a section on fats, oils, and waxes, on nitrogen-assimilation; on enzymes, tannins, glucosides, caoutchouc, etc. There are also sections on a "complete" analysis of a plant, and on respiration. Finally, we have a number of sections of a miscellaneous nature, such as the sterile culture of the higher plants, the determination of the surface tension, permeability, and osmotic pressure of plant cells, the use of ether, hot water, and other means for producing precocious sprouting, the measurement of growth, "bleeding," and transpiration. Finally, tables are given showing the colour changes of various indicators for the determination of the hydrogenion concentration of cell-saps by means Friedenthal's method.


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(3) Plane Trigonometry. By Prof. H. S. Cars-
law. Pp. xviii+293. Price 4s. 6d. Solutions
of the Questions in Plane Trigonometry.
Prof. H. S. Carslaw. Pp. 179. Price 6s. 6d.
net. (London: Macmillan and Co., Ltd., 1915.)
(4) Numerical Trigonometry. By N. J. Chignell.
Pp. xii + 126. (Oxford: Clarendon Press,

he separates the educational grain from the educational chaff, and gives us the grain. So much is found fit for discarding as chaff that the author finds space for treating trigonometry, Cartesian geometry, and the calculus, in addition to a discussion of such recent work as that on the complete number-scale.

Throughout the book Prof. Nunn's knowledge of psychology is brought to bear to improve the order of treatment. In the customary treatment negative quantities are introduced early, and form a serious stumbling block. Prof. Nunn restricts the subject to "non-directed quantities" for a considerable time. In consequence the pupil first meets negative quantities at a more mature age and with a mind more developed algebraically, and is better fitted to grasp the new idea.

The complete number-scale is introduced with the view of clearing up the doctrine of limits. The treatment is lucid and simple, and the student of this book will gain clear views on a matter on which even the best writers of books on the calculus have hitherto gone wrong. The book is one in a thousand, and all students who go beyond the non-specialist school course will gain enormously by its study.

(2) Castle's "Workshop Arithmetic " is a book on which a boy would be glad to be brought up even if he is not destined to be an engineer or builder (for whom the book is specially designed). The questions come straight from the workshop and other everyday sources, and the human interest never fails. While the author's language sometimes jars upon us, as when he says, “Compute the following operation, 47199÷2'363" (p. 7), or "The objects are not the same dimension at different places" (p. 30), we yet fear that presentday usage justifies this use of operation, and the omission of a preposition before the same dimen

The largeness of the square ruling of some diagrams deserves a special word of praise for its clearness.

(3) Prof. Carslaw's "Trigonometry" passes over the early portions of the subject rapidly. It is suited to the strong digestion of the specialist It holds schoolboy and to university students.


a midway position between the older style of book which includes all the attractive backwaters and exercises in manipulation, and the modern book 1914.) Price 2s. 6d. which aims at putting a useful tool in the stu(5) Longman's Modern Mathematical Series. Ex- dent's hands and restricting proofs and explanaercises in Arithmetic and Mensuration. By P. tions to bare necessities. The book includes all Abbott. Pp. ix + 524. With Answers. (Londɔn : that has been customary, and improves on the Longmans, Green and Co., 1913.) Price 4s. 6d. older books by introducing numerical work at an (1) ROF. NUNN'S three volumes form a early stage. It is well suited to the many teachers unique treatise on the study of algebra. who desire the new but hesitate to break with the Beginning from the first notions in the subject old. The solutions in the key show careful work, |


and the type is excellent in both books-the text possible, without artificial aid, to render the soil and the key.

(4) Mr. Chignell's book is planned on the wise modern method of beginning trigonometry with a numerical treatment of the ratios, and postponing the addition theorem and other formulas until the student has thoroughly grasped the meaning of the ratios. The solution of the oblique triangle is effected by dividing it into two rightangled triangles, a simple method which is in every way sufficient for non-specialists; the halfangle formulas were invented for astronomical use, and may very well be left to astronomers and other specialists. The quantity of exercises is ample for all purposes, and the wise schoolmaster will use only a minimum number of the introductory tests and pass rapidly on to the "problems' of human interest.

(5) For the students who use Mr. Abbott's book the bad old rule-of-thumb days are over. Vulgar Vulgar fractions are introduced in most practical fashion, fractions of lengths and areas being shown in diagrams. Then follow decimals in equally practical fashion by means of the paper abacus which served merchants up to the time of the invention of the zero; and so on in corresponding treatment throughout the range of mensuration.


The relation (a+b)2=a2+ b2+2ab we pleased to see treated as the algebraic expression of a property which is fundamentally geometrical; too often the relation is taken to be fundamentally algebraic, and the geometrical property reduced to the status of an illustration. The square-ruled diagrams are sometimes in tenths of an inch and sometimes in millimetres. The former are better, the latter being trying to the eye; and for many purposes quarter-inch or half-centimetre ruling would be better than either. The bulk of the exercises have the great merit of being drawn from human life. D. B. M.

OUR BOOKSHELF. Practical Irrigation and Pumping. By B. E. Fleming. Pp. xvi +226. (New York: J. Wiley and Sons, Inc.; London: Chapman and Hall, Ltd., 1915.) Price 8s. 6d. net.

IT is somewhat difficult for the inhabitants of a country intersected by numerous streams and characterised by an ample and fairly uniform rainfall, to realise the disabilities under which agriculturists labour in other lands less favoured with automatic supplies of natural moisture. The great plains of India, the immense tract of Egypt and the Sudan, and the vast expanse of North America lying west of the 100th meridian, comprising some dozen States and forming about onethird of the total area of the United States, are instances of those arid regions in which it is im

productive in any effective degree. What this means may be gauged from a statement in the prefatory note of the volume before us, that up to July, 1910, it is estimated that a sum of more than 60,000,000l. had been sunk in the reclamation, by irrigation, of 14,000,000 acres in the Western States of America.

The purview of Mr. Fleming's book is limited to a consideration of irrigation by means of pumping underground water, as practised in the United States, and in so far as this aspect of the subject is concerned, it is treated fairly comprehensively. The author enters succinctly, and at the same time with some degree of detail, into the various problems connected with the sinking of wells and the installation of a pumping plant. Considerable space is devoted to a discussion of the merits and capabilities of the centrifugal pump, and a noticeable feature is the number of performance diagrams of various-sized pumps of this type. Reciprocating pumps are only lightly touched. upon. Prime movers and windmills are described. There is a chapter on the cost of pumping operations which contains some useful information; the governing conditions, as already stated, are those prevailing in the Western States, and, consequently, the facts are not generally intended for wider application. Within the limits set down by the author, this little volume is an interesting and practical handbook, based on his personal experience, some of which, he remarks, has been B. C. "rather bitter."

Brazil (1913). By J. C. Oakenfull. Fifth Edition. Pp. viii+604. (Frome: Butler and Tanner 1914.) Price 7s. 6d. net.

THIS account of Brazil is the fifth revised edition of a handbook originally published in 1909, and distributed at the cost of the National Government. It discusses in detail the geography, history, natural productions, and economic resources of a country including an area of 8 million kilometres and an estimated population of 24 millions. The book is well arranged, the information is based on the most recent official reports, and it is provided with good maps and illustrations. Brazil in its geographical features presents the most varied characteristics-the great river basins of the Amazon-Tocantins and La Plata, a shapeless mass of highlands, and a narrow coastal region. In its highland region suited for an agricultural and pastoral life, its vast forests providing unlimited supplies of valuable timber, its coffee, sugar, tobacco, and other useful products, it remains one of the few areas suitable for extensive development by settlers from Europe, a fact which has been fully grasped by the German Government, ever in search of new colonies and desirious of securing a footing on the continent of America.

The book is admittedly intended to press the claims of Brazil on the colonist. Since 1820 3 millions of emigrants, of whom the majority are Italians, have reached its shores, and progress has recently been made in attracting Japanese

emigrants. But Mr. Oakenfull goes beyond his brief when he dwells on the superiority of Brazil to the British Colonies, particularly in relation to the price of land. It must be remembered that Brazil is as yet only partially developed, and the present economic situation may be gauged by the value of the national securities. While Canada 3 per cents. are now quoted at 83, Brazil 4 per cents. of 1910 stand at 49. No doubt this is owing to temporary causes, but for the intending emigrant the contrast is significant.

Improved Four-Figure Logarithm Table, Multiplication and Division Made Easy. By G. C. McLaren. Pp. 27. (Cambridge: At the University Press, 1915.) Price is. 6d. net. THESE tables aim at popularising logarithms. Like other four-figure tables they give the logarithms of numbers from 1000 to 9999. While the ordinary tables give these in one opening of two pages by means of difference columns, Mr. McLaren gives all the 9000 entries independently, and so of course without difference columns. His tables consequently occupy nine openings or eighteen pages. Rapid reference to the various openings is made possible by "thumb-indexing," and for speed there is probably nothing to choose between these tables and the customary ones. There is a gain in accuracy, both because the use of difference columns is not trustworthy in the last figure, and because of Mr. McLaren's ingenious device of showing the last figure to the nearest third. Whether these tables seriously reduce the skill required for their use as pared with the customary tables we have some doubt. We think their appeal will be chiefly to those calculators who require slightly greater accuracy than the customary tables allow and who at present use five-figure tables. D. M. Joseph Pennell's Pictures in the Land of Temples. 40 illustrations. (London: William Heinemann, 1915.) Price 5s. net.


THE sub-title to this attractive volume very well describes its contents. It runs: "Reproductions of a series of lithographs made by him in the land of temples, March-June, 1913, together with impressions and notes by the artist." The illustrations start Taormina, proceed around Sicily-thence to Italy, and are continued in Greece. The book is dedicated to Mr. R. M. Dawkins, late director of the British School at Athens, who showed Mr. Pennell where he would find the temples. The artist says with becoming modesty that having seen the pictures Mr. Dawkins expressed the the opinion that they had "something of the character and romance of the country." It is unnecessary here to praise the work of so distinguished an artist; it is enough to say that the pictures convey just the impression which the temples made upon Mr. Pennell: great feeling of the Greeks for site in placing their temples and shrines in the landscape-so that they not only became a part of it, but it leads up to them."



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

The Continuous Spectra of Gases.

IN spectroscopic literature there are many casual references to a continuous background in the vacuum tube spectra of various gases, such as oxygen, chlorine, etc. Usually these observations appear to have been confined to the visible region, and I can recall no comments on continuous spectra in the ultraviolet except in the case of hydrogen. Schniederjost (Zt. f. Wiss. Phot., 1904, p. 265) and Friederichs (Bonn Diss., 1905) observed such a spectrum at low pressures, which extended to a wave-length of about 2100. The latter attempted to use the uncondensed discharge through a small capillary tube at about 2 mm. pressure as a source for the photography of absorption spectra, but found that the results were unsatisfactory, even with exposures varying from twelve to twenty-four hours.


In photographs of the hydrogen spectrum obtained with a large two-prism quartz spectrograph I have frequently observed this continuous spectrum. though the resolving power of this spectrograph in the extreme ultra-violet is greater than that of a five-inch grating in the first order, there is no evidence of resolution into lines or bands. The spectrum appears to be uniformly continuous, and it seems likely that its gradual fading out in approaching the wave-length 2100 is due rather to the absorption of the thick quartz system than to the lack of these wave-lengths in the emitted light. It appears to be due to pure hydrogen, for successive improvements in purity due to the removal of oxygen, water vapour, and nitrogen cause no noticeable change; nor does the addition of a trace of oxygen to hydrogen previously freed from that gas so far as possible cause any appreciable difference.


It seems very unlikely that a continuous spectrum can arise from free vibrations within the atom or molecule, hence it has been usually ascribed to molecular collisions. In comparing different gases at the same pressure, the number of collisions would depend mostly on the mean velocity of the molecules, so that the number of collisions would rapidly diminish as the molecular weight increases; hence we might expect that the continuous spectrum of a light gas would be stronger than that of a heavier gas. This was found to hold good for hydrogen, helium, and Photographs were obtained of the spectra of these three gases in vacuum tubes prepared by Hilger. The pressure was about the same in all. With a twominute exposure, the continuous spectrum of hydrogen was very intense, that of helium about half as strong, and that of neon about one-third as strong. They all extended to about the same limit-that set by the In all these cases the transparency of the quartz. uncondensed discharge of a medium-sized induction coil was used. The introduction of a condenser almost completely obliterated the continuous spectrum. When a condenser is used the radiation probably comes from dissociated ions, with free periods little disturbed by molecular collisions.

Nitrogen, krypton, and xenon did not show any continuous spectrum.

excellent service as sources for the study of absorption Some tests showed that hydrogen tubes may render spectra in the ultra-violet. It was not found advisable use capillary tubes, or to work at such low pressures as Friederichs did. The best results were


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