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administration that is so completely the need of the hour.

The intention of the Minister has been pretty clearly expressed. Production is to be speeded up by using at first the most perfectly equipped shops, and by drawing labour and machines from those less fully qualified to undertake the work. It is to be hoped that an effort will be made to work three shifts in the twenty-four hours. There seems to be no reason why the students in the scientific and technological faculties of the universities and older boys in public schools should not be mobilised for this purpose. The greater number of jobs are carried out on automatic machines, the control of which can be learnt in a fortnight or less. The main object, however, is that the most efficient and economical methods of production must be adopted; the small shop, therefore, must stand out; and the individual must express his patriotism in co-operative effort.

as a war of guns and ammunition, and if we are to hasten that end which we believe to be inevitable, we must concentrate every element of scientific knowledge and technical skill into its prosecution.

Scientific discovery, mechanical invention, and a highly technical organisation as employed by the Germans are only to be beaten by similar forces arrayed against them. It is not a time to say what ought to have been in the past, but what should be now and in the immediate future. We know that up to a certain point the scientific resources of the country have been drawn upon, but beyond the fact that one man is working at explosives, another at the Royal Aircraft Factory, and a third is testing for the Admiralty, we want to feel that these are only details of a wider scheme so perfect in its organisation that the full effect of our forty-five millions of people is brought to bear upon the enemy. Many people would sleep more peacefully if they knew that every technically trained man in the universities, university colleges, technical institutions, and in the Government Departments was not doing his "business as usual," but making it his special business to provide the nation with the scientific material and machinery by which alone can our forces achieve success in the present conflict.

The Electron Theory of Matter. By Prof. O. W.
Richardson. Pp. vi+612. (Cambridge: At
the University Press, 1914.) Price 18s. net.

HIS book is based on a series of lectures
delivered by Prof. Richardson at the
University of Princeton, and gives a general
survey of the electron theory. The book. starts
with an account of the elementary prin-
ciples of the theory of electricity and mag-

Not a great deal of consolation is to be derived from the administration of local committees constituted by a careful balancing of interests and "municipalised" by the presence of the chief magistrate. If the local employers, managers, or foremen are giving the most effective service in their own works they will have little time for attending committees. A committee is as effective in affording opportunity for personal differences as it is for securing unanimity as to method and aim. The more such bodies are used in an advisory, and the less they are used in an executive capacity, the happier will be the result of their efforts. For getting things done one autocrat is worth twenty committees, provided that he has common sense and is neither a politician nor a lawyer who regulates action by precedent. The work of organising our scientific and technical forces should not be put into the hands of men whose knowledge is limited to the ety-netism, and a discussion of phenomena which mological derivation of the names of things required--at least not in time of war, and it is imperative to consider whether the real resources of technically trained men have been tapped. A great many have entered the army and have been drafted into regiments where their specialised knowledge is of little use. Even then the fact that they can write has resulted in their being burdened with clerical work, which could as easily be done by women. But there are many men who for more or less adequate reasons are not in uniform and are only awaiting the call to industrial service. In comparison with previous wars the present conflict is not a war of men so much

can be explained on the general Maxwell theory. From this we are gradually led to the discussion of such phenomena as dispersion and selective absorption, which have first found satisfactory explanations on the electron theory. Next follows a closer account of the theory of the mechanics of electrons, containing detailed considerations of the problems of electromagnetic mass, the radiation from an accelerated electron, and the properties of moving systems. This part ends with a brief account of the principles of the theory of relativity. After this we return again to the consideration of the general properties of matter, and the results deduced in the preceding chapters are

employed in a discussion of the bearing of the electron theory on the problems of temperature radiation, magnetism, and the theory of metallic conduction.

Finally, after an account of the theories of spectroscopic phenomena and the phenomena of radio-activity and X-rays, we are led into a discussion of the theories of the constitution of the atom.

It will be seen that the book covers a very extensive field. To give an adequate representation of the entire electron theory is naturally a task of the greatest difficulty, but the author appears to have done this in an admirable manner. Of necessity the treatment is at many points very restricted, but almost all points of general interest are considered. If any problem is treated more fully than others it is the theory of metallic conduction, as might naturally be expected from the author's own work. The exposition is throughout very clear and concise, and Prof. Richardson possesses a great gift of making even complicated arguments very easy for the reader to follow. A close connection with the latest experimental progress is everywhere maintained, and problems. which involve hitherto unsolved difficulties are treated in a manner very far from being dogmatic.

In reading Prof. Richardson's book one gets ample opportunity to think about the present state of theoretical physics. The collection of the numerous brilliant achievements of the electromagnetic theory and the electron theory fills one with the greatest admiration. Still, the difficulties, first discovered with relation to the problem of temperature radiation and later in other problems,

ment, it would, perhaps, be to examine the constitution of the special atomic systems actually existing, and then, by means of the directly observable properties of matter, possibly to deduce the general principles. If so, the evolution would be exactly the reverse of that anticipated.

In the present unsettled state, Prof. Richardson's book, which gives a balanced and masterly survey of a wide range of knowledge, will no doubt be especially welcome. It can be most heartily recommended, not only to students who seek an introduction to the electron theory, but to all interested in the modern development of physics. N. B.


(1) The Standard Cyclopedia of Horticulture. Vol. ii., C-E. By L. H. Bailey. Pp. 603-1200. (New York: The Macmillan Co.; London: Macmillan and Co., Ltd., 1914.) Price 25s. net. (2) Forage Plants and their Culture. By C. V. Piper. Pp. xx+618. (New York: The Macmillan Co.; London: Macmillan and Co., Ltd., 1914.) Price 7s. 6d. net.

(3) American Science Series. Essentials of College Botany. By Prof. C. E. Bessey and Prof. E. A. Bessey. Pp. xiv + 409. (New York: Henry Holt and Co., n.d.) Price 1.50 dollars. (4) The Story of Plant Life in the British Isles: Types of the Natural Orders. Vol. ii. By A. R. Horwood. Pp. xiv +358. Vol. iii. Pp. xvi+ 514. (London: J. and A. Churchill, 1914.) Price 6s. 6d. net each.

HE second volume of Bailey's "Cyclo

seem to be so great and of such a fundamental (1) Tedia of Horticulture" contains in

character that the theory will need very great alterations. Even if a way is indicated by Planck's theory no satisfactory solution of the difficulties has yet been found. In text-books only a few years old one finds great enthusiasm over what was called the future programme of the electromagnetic theory. It was believed that this theory constituted a final accomplishment of ordinary mechanics, and there appeared to be no limit to the application of the general principles of the theory. This attitude has changed most decisively. The impression obtained by reading the present book, however, is anything but merely disillusioning. Scarcely at any time has our knowledge increased so very rapidly as of late years, and, above all, we now possess much more powerful methods of experimental attack than were dreamed of a short time ago. Especially investigation of the radiation from radio-active bodies has proved most efficient in disclosing the internal structure of the atoms. If at present we may speak of a programme for the future develop

formation on every subject pertaining to horticulture from "Cabbages" to "Extension Teaching in Horticulture," and is of a remarkably comprehensive character.

Every plant of interest the name of which lies between these two extremes is referred to; the derivation of the name is given, descriptive particulars of the plant, its geographical distribution, and notes on its method of cultivation go to make up each successive article. The book, though written primarily for the American horticulturist, contains much valuable information for extraAmerican countries. Certain articles, as that on the chestnut, remind one of the American origin of the work, as we are fortunate in being free from the dreaded chestnut fungus Diaporthe parasitica, which has caused such havoc in the United States. Diseases and insect pests receive extensive notice, and some forty double-column pages are taken up with descriptions of the various pests and the means of combating them. As with other

articles, the text figures of fungi and insects are numerous and on the whole well-executed.

The genus Crataegus, which reaches so conspicuous a development in the States, has been carefully worked up by Prof. Sargent, and some nine hundred species are now recognised, to the confusion of European botanists and gardeners. In the encyclopædia the account of the genus occupies nearly eleven pages from the pen of Mr. Rehder, and the key to the fifty species which he mentions lends considerable value to the article. Eucalyptus again, another enormous genus but this time of introduced plants, occupies twelve pages, and there is a large illustration of a very fine specimen of E. viminalis growing in California. The key, which refers to as many as seventy-six species, is followed by short, useful descriptions with a few text-figures interspersed. Other large genera which fall within the compass of this volume are Cereus, Dendrobium, Echinocactus, Echinocereus, and Euphorbia, all of which receive very careful treatment.

There are a certain number of full-page illustrations, either in colour or in the form of photographic reproductions, which are well executed; among the latter that of cranberry-picking in a New Jersey bog makes a delightful picture; the coloured plates might have been dispensed with as they are of no particular interest. It is diffiIt is difficult to find any plant of importance or value which has been omitted. Owing to the large amount of material included, the volume is unduly bulky, and like other American publications suffers from its weight.

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(2) Forage Plants and their Culture" comes from the master-hand of the agrostologist in charge of forage-plant investigations of the United States Department of Agriculture, and is a valuable and well-illustrated agricultural handbook.

The introduction deals with forage crops generally, and in connection with the legumes an account of root nodules and nitrification is given. The chapters which follow treat of the preservation of forage and choice of crops, in which the results of feeding experiments, chemical analyses, the chemical composition as affected by the state of maturity of the crop, and other particulars are given.

The chapter on "Seeds and Seeding" is illustrated by useful plates showing the noxious weed seeds found among farm seeds. "Meadows and Pastures" and statistics of forage crops occupy the two next chapters. These are followed by detailed accounts of various crops, such as timothy, blue grasses, meadow grasses, the bromes, the sorghums, millets, and other grasses which figure prominently among the valuable forage plants of

the United States. Among the legumes, alfalfa or lucerne occupies the first place, and the various clovers, peas, and vetches, soy beans, and other sub-tropical leguminous plants are discussed in some detail.

Root crops also come in for their share of attention. The book is written for the agriculturists of the United States, but the information it contains should prove of value to agricultural workers in South Africa, Australia, parts of northern India, and British East Africa, where many of the forage plants mentioned in the book can be successfully grown.

(3) A text-book which is said to contain only the essentials of the subject and written for "college teachers" may well be an uninteresting production, and that by Profs. C. E. and E. A. Bessey cannot be considered inspiring. It is to be hoped that the teachers who will use the book have already had their interest in botany roused and their enthusiasm for the subject fired by other teachers before taking up "the essentials" as a course of study. Not even the illustrations lend a helping hand, as they are singularly poor, and those of nuclear division are almost childish.

Though largely a very elementary treatise, the chapter on the chemistry of plants, with its masses of formulæ, is a formidable affair, and is too condensed to be of much practical value. The latter part of the book consists of a rapid classificatory survey of the vegetable kingdom with poor little figures. The book should not meet with much popularity on this side of the Atlantic.

(4) Mr. Horwood's second volume follows similar lines to the first one previously reviewed in NATURE. The introduction gives a rapid review of general botanical information which is not always sound; the statement on p. 8, for instance, that if the nucleus is damaged the plant dies, would suggest to the uninitiated that a plant possesses only a single nucleus. Other sweeping assertions, such as "the endodermis. . . is graviperceptional," that parasitic plants possess roothairs, and that "the protection of the stomata from being clogged is ensured by the provision of hairs and their occurrence on the under-side of the leaf," may be received with caution by those who have a wider knowledge of botanical facts.

Mr. Horwood, after mentioning that "very little free nitrogen is obtained from the air by plants," proceeds to remark on the temperatures favourable to plant growth, and apparently without having made his calculations from Centigrade to Fahrenheit, states that the "most suitable temperature for plant growth is about 28° C., though plants can grow below this," and further, "above a temperature of 56° C. plants usually die." This

latter statement corresponds fully with our own experience. For the rest, the book treats in detail of the Thalamiflora, Calycifloræ, and certain Gamopetalæ; descriptions of the plants and their natural orders are given, and there are numerous illustrations reproduced from photographs.


The author states that "the facts of botany, like those of zoology . . . are capable of reduction to orderly arrangement," and it is to be regretted that he has not found himself able to follow out his opening text in the ordering of his material.

The third volume recently issued completes the work. There are 95 pages of introduction dealing with germination, plant formations, and many other unrelated subjects. These are followed by three chapters devoted to the Corollifloral and Apetalous Dicotyledons, and the Monocotyledons. There are numerous photographic illustrations.


(1) Practical Heat, Light, and Sound.

By T. Picton. Pp. xv+151. (London: G. Bell and Sons, Ltd., 1915.) Price 1s. 6d.

(2) Notes on Practical Physics for Junior Students. By Prof. C. G. Barkla and Dr. G. A. Carse. (London: Gurney and Jackson, 1915.) Price 3s. 6d. net.

(3) A Text-book of General Physics for College Students. By Dr. J. A. Culler. (Philadelphia and London: J. B. Lippincott Co., 1914.) Price 7s. 6d. net.

(4) Manuale di Fisica. Vol. ii., Acustica, Termologia, Ottica. By Prof. B. Dessau. (Milan : Società Editrice Libraria, 1915.) Price 15 liras. (1)

inertia several questions are associated with each exercise, which must be answered before the student is allowed to proceed to the next experiment. The instructions are brief but sufficient, and can be thoroughly recommended for class-work. It may especially be noted that in the optical experiments a method is used which makes visible the paths of the rays-a considerable gain at this stage. The sections on concave lenses need revision, as the methods given are not the best available; also it would be a great advantage in future work if some use were made of books of tables, especially of reciprocals in lens experiments.

(2) Prof. Barkla and Dr. Carse's book is apparently a collection of some of the instructions used in the authors' laboratory at Edinburgh University. For the students there it will doubtless supply all that is required in the elementary classes, but beyond this it is not clear that it will fill any gap in the existing literature. As the directions are not written with reference to special forms of apparatus, they are available for the senior forms of schools. The first chapter on "Treatment of Observations and Determination of Error" is the best elementary discussion of the subject that we have seen.

(3) A comparison of English and American textbooks of physics for colleges reveals a series of interesting differences. Taking them in order :(1) American authors usually reduce the mathematical portions to a minimum; a rather unexpected feature if it be true that instruction in the States is so much more systematic than here, for in that case the usual excuse-that the student's mathematical knowledge behind his physical requirements should not be allowable. (2) More emphasis is placed on technical applications; a great advantage if the corresponding theory is developed. (3) There is a determination to be up to date as regards modern theories.

MALL school text-books frequently receive but scant attention from reviewers, but, when it is remembered that it is exactly in the earliest stages of a subject that students should be led to acquire those correct habits of thought and outlook without which real advance is impossible, we are not altogether persuaded that this attitude can be justified. It was with this in mind that Mr. Picton's book for the middle forms of schools was examined. An experimental exercise should have for its objects, first, the elucidation of physical principles, and secondly, should show how to conduct the measurements so as to obtain the best numerical result with the means at the disposal of the class. Most teachers will agree that the second of these is more easily secured than the first. As the preface puts it:— "A pupil may carry out conscientiously the written instructions, obtain a 'good result,' write a neat account, and yet have very indistinct ideas (and) often no ideas at all) of the principles underlying the experiment." To overcome this mental

Sceive but scant attention from requiremtis should not be allowable. (2) More

It is this last feature that is most strikingly in evidence in Dr. Culler's text-book. The author has set out to produce "a logical development of the live topics which, it seems, should be included in a text-book for college students," and, on the logical side, has not been altogether successful. To give two illustrations :-He desires to explain all the elementary electrical phenomena in terms of electrons, and finds it necessary to start the first paragraph with "What electricity is," followed on p. 3 with "Evidence for the electron theory," including a description of Thomson's experiments on kathode rays. Similarly, in the first page on magnetism we find ourselves immersed again in electrons. In each case terms have to be used which, at that stage, are incapable of

definition, and a number of statements are made which the reader must take on faith. In several instances the treatment is too sketchy to be of any practical value; thus two pages are allotted to photometry, half a page to thick lenses (in spite of their technical importance), five pages to radioactivity, and twenty-three to sound. Nevertheless, if these blemishes are allowed for, it may be granted that the book is clearly and interestingly written, well got up, and likely to excite and retain the interest of the reader; but to take full advantage of its good qualities the student must not come to it as a beginner.

(4) Prof. Dessau's book, the second volume of a large text-book of physics, is admirable in its elegance, clearness, and choice of matter. The chapters on thick lenses and optical instruments may especially be mentioned as models of conciseness and lucidity. (Why is it that modern methods of determining refractive indices receive no mention in English books on physics other than those on physical chemistry?) But surely a book of 600 pp. should have an index !


(1) Evolution and Disease. By Dr. J. T. C. Nash. Pp. viii+73. (Bristol: John Wright and Sons, Ltd.; London: Simpkin, Marshall, Hamilton, Kent and Co., Ltd., 1915.) Price 3s. 6d. net. (2) The Vicious Circles of Neurasthenia and their Treatment. By Dr. J. B. Hurry. Pp. xv+90. (London: J. and A. Churchill, 1915.) Price 3s. 6d. net.


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N this work Dr. Nash first traces the history of certain epidemic diseases, in particular the Black Death, during the Middle Ages in Great Britain. An interesting chapter deals with the medieval psychopathic epidemics, such as the dancing mania. Much of this has necessarily appeared elsewhere, but it is none the less

convenient to have the scattered literature of the subject thus briefly epitomised. The reader will probably turn with most interest to the chapters dealing with evolution and disease-in particular with the evolution and mutations of disease germs. As regards diphtheria, for example, the author states that diphtheroid organisms in throat swabs are uncommon except in cases of definite sore throat or in "contacts" with diphtheria or sore throat, that genuine cases of diphtheria with of diphtheria with typical diphtheria bacilli often show later only diphtheroid bacilli in the throat swabs, and that some streptococci, some torulæ, the Klebs-Löffler bacillus, Hofmann's bacillus, and certain other diphtheroid bacilli, have a common ancestral origin, and concludes that the fact that bacteria and protozoa can be profoundly affected by en

vironment is abundantly established, and evolution in relation to the germ cannot be gainsaid.

A topical interest is introduced in the final chapter on war as a factor in the evolution of epidemics.

(2) Dr. Hurry describes with considerable skill the vicious circles associated with that protean disorder known as neurasthenia. As an instance of a "vicious circle," that in connection with the heart may be quoted :

"The sequence of events is somewhat as fol- I lows: The fear of organic heart disease leads to auto-suggested sensations in the cardiac region, followed by disturbance of the cardiac action, such as rapid heart, occasional extra beats with palpitation, and an intermittent pulse. The associated sensations then arouse distress and terror, which in their turn further disturb the cardiac action. Such attacks are especially common at night, and may be caused by nightmare, and the operation of this Circle may reduce the neurasthenic Even fatal person to a condition of utter misery. syncope may result."

It will thus be seen that the neurasthenic condition becomes evolved, as it were, given some factor which serves to start it and set in train the "vicious circle."

As regards treatment, while the principles are, it is true, indicated, the physician who desires real guidance will find little to help him, and we think that this part of the book might be usefully extended. R. T. H.


By Prof. Heating and Ventilating Buildings. R. C. Carpenter. Pp. xiv +598. Sixth Edition. (New York: J. Wiley and Sons, Inc.; London: Chapman and Hall, Ltd., 1915.) Price 15s. net.

DURING the twenty years since this book was first published there have been many changes in methods of heating and ventilation. The present edition has been enlarged considerably by the addition of matter necessary to make it an up-to-date treatise on the subject. The author, who is well known as the professor of experimental engineering at the Cornell University, has dealt with the principles in a scientific manner, and has placed the various practical rules as far as possible on a rational foundation, at the same time avoiding the use of complicated mathematics. The earlier chapters are taken up with the properties of heat, the flow of water, steam and air, and the boilers and fittings steam and hot-water heaters. required for The remainder of the book contains thoroughly well illustrated descriptions of modern heating systems and includes gravity steam-heating, pump. return steam-heating, hot-water and hot-air systems. There are also sections dealing with mechanical ventilators, heating with electricity,

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