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A MONOGRAPH OF

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OF INDIA.

By Capt. S. P. JAMES, M.B. (Lond.), and
Capt. W. GLEN LISTON, I.M.S.

With 15 Full-page Coloured Plates, 64 Illustrations in Half-Tone (on 15
Plates), a Map, and 30 Diagrams and Illustrations in the Text.

Second Edition. Demy 8vo, cloth. 7s. 6d. net.
MALARIAL FEVER

AND MALARIAL

PARASITES

TELESCOPE.

By E. WALTER MAUNDER, F.R.A.S.

An Introduction to the Knowledge of the Constellations, and to the Study of the Heavens with the unassisted Sight. Fully Illustrated with full-page Plates, and with Maps and Charts, also twelve Star Maps, forming a COMPLETE CELESTIAL ATLAS.

W. THACKER & CO., 2 CREED LANE, E.C.

PROF. SCHUSTER has done excellent service to teachers and students alike by publishing this book, which fills a very obvious gap. It is an introduction to the theory, and purposely does not deal with details of methods of measurement or instrumental appliances; these are properly left to courses of laboratory instruction. At the same time the necessity for experiments and observations is everywhere present to the author's mind. The book is not a mere mathematical treatise on simple harmonic motion; indeed, the analysis is generally easy, and purely mathematical difficulties are avoided. Prof. Schuster writes as a physicist. The physical meaning of the steps and processes employed is everywhere insisted on, and the student is made to think through

out.

The standpoint of the author is best explained by two short extracts from his preface. After stating that the elastic solid theory of optics as developed in England by Green and Stokes has proved insufficient, he continues,

"Those who believe in the possibility of a mechanical conception of the universe, and are not willing to abandon the methods which from the time of Galileo and Needham have led uniformly and exclusively to success, must look with the gravest a growing school of scientific thought which rests content with equations correctly representing numerical relationships between different phenomena, even though no precise meaning can be attached to the symbols used.”

concern on

And again,

on

a

"The equations which at present represent the electromagnetic theory of light have rendered excellent service, and we must look upon them as a framework into which a more complete theory must necessarily fit, but they cannot be accepted as constituting in themselves a final theory of light. "The study of physics must be based knowledge of mechanics, and the problem of light will only be solved when we have discovered the mechanical properties of the ether. While we are in ignorance on fundamental matters concerning the origin of electric and magnetic strains and stresses, it is necessary to introduce the theoretical study of light by a careful treatment of wave propagation through media the elastic properties of which are known. A study of the theory of sound and of the old elastic solid theory of light must precede therefore the introduction of the electromagnetic equations." The book proceeds on these lines; the first part is almost entirely kinematical; the second part deals with theories of light, starting first from an analysis of the equations of motion of an elastic medium; then passing to those of the electromagnetic field, and developing the two theories side by side as far as possible.

To turn now to some details. In the earlier chapters, in accordance with the views expressed in

the preface, the author deals with the properties of vibrating mechanical systems, e.g., the air in a closed space, or a stretched string. After some discussion as to periodic motion in general, the equation of motion for an elastic body, propagating plane waves of distortion, is found in an elementary manner, and certain fundamental results are shown to follow from its similarity to the equation for a stretched string. Huyghens' principle of the superposition of small motions is explained, and then the reader, after a chapter on the nature of light, is introduced to the principle of interference.

The problems of diffraction are treated very fully, making use of the method of Fresnel's zones; the method is modified by the author in a manner which permits numerical results of a high order of accuracy to be obtained without the introduction of Fresnel's integrals.

After an interesting chapter on diffraction gratings we come to one on the theory of optical instruments, in which the resolving power of telescopes and spectroscopes is carefully discussed. The theory of the microscope does not find Prof. a place in Schuster's book; perhaps it belongs rather to the domain of geometrical optics.

Fresnel's theory of double refraction is given very fully, and it is based not on any unsound dynamical reasoning, but on the observed experimental fact that the velocities of wave propagation of a plane wave moving through a crystal are given by the axes of the section of a certain ellipsoid by the plane of the wave; this is clearly the right way to deal with this problem. When the laws of the propagation of light in a crystal are once determined the discussion of the rays and brushes due to the interference of polarised light follows easily, and thus we are led to Part II., which, as has been already said, deals with theories of light.

The equations of motion are found both on the elastic solid and electromagnetic theory, and the simpler phenomena are considered from both standpoints.

The weak points of the elastic solid theory, however, soon manifest themselves, and for the rest of the book the equations of the electromagnetic theory are mostly used; in dealing with dispersion Sellmeyers' hypothesis of sympathetic vibrations is applied to the electrons of a molecule, following Drude, and the usual expression connecting the refractive index and the frequency obtained; the same method is applied to explain the rotatory effects of sugar and other active substances, and in a most interesting series of sections the Zeeman and other allied effects are dealt with. In the last chapter we have a discussion on the nature of light as the resultant disturbance arising from the individual vibrations of the molecules of the source. Enough has probably been said to show the nature of the book, but one characteristic should not be omitted. Prof. Schuster has included short historical accounts of the men who have made the science of physical optics. Among them we find the names of Young, Fresnel, Cauchy, Stokes, and Maxwell; the interest

In conclusion, it is perhaps sufficient to say that the treatment is marked throughout by the author's well-known and admirable lucidity of style. Take, for example, the last paragraph in the book discussing the result which follows from the fact that as an extreme case for the green thallium light the periods of 88 per cent. of the vibrating molecules are identical within about one part in two millions.

we

"If you had a great many clocks, and found that taking their average rate to be correct, not more than one in eight would be wrong by a second in twenty-three days, that would represent the maximum amount of variation which one interpretation of the experiment allows us to admit in the case of molecular vibrations. But would any maker undertake to supply you with a number of clocks satisfying that test? If, further, it is considered that the limits have chosen for the possible variations of molecular vibrations are far too great, we see that though Sir John Herschel's saying that atoms possess the essential character of manufactured articles is still correct, yet no manufactured article approaches in accuracy of execution the exactitude of atomic construction. We may conclude with Maxwell that Each molecule therefore throughout the universe bears impressed on it the stamp of a metric system as distinctly as does the metre of the archives at Paris or the double royal cubit of the Temple at Karnac.'"

Techno-Chemical Analysis. By Dr. G. Lunge.
Translated by A. I. Cohn. Pp. vi+136. (New
York: Wiley and Sons; London: Chapman and
Hall, Ltd., 1905.) Price 4s. 6d. net.
R. PROST'S manual contains

a

number of

DR. selected methods dealing more particularly with mineral and metal analysis which have been compiled, so the preface states, for the use of the "industrial chemist," and which the author assures us are the result of his own experience or that of specialists with whom he is in touch.

The analysis of mineral products-silicates, phosphates, clays, cements, iron and iron ores, and the assaying of lead, silver, gold, &c., have been so fully elaborated that no analyst deserving the name would be satisfied without knowing the latest improvements in the methods connected with his own industry. A chemist in an iron works, for example,

wants all the information he can obtain from the

specialist who has made a minute study of iron and steel analysis, including the character of etched surfaces, and through whose hands a large variety of specimens have passed The same, of course, applies to raw materials and finished products of other manufactures. The works analyst is not a student, and though he may wish to be informed on analysis in general, it is not essential to his business.

Does Dr. Prost's book as a whole fulfil its promise? Whilst there is no doubt that many of the

preface, and will be found serviceable to the works analyst, it must be confessed there are also many others which fall short of it. In too many instances there is a lack of descriptive detail, an absence of reference to recent improvements, and the omission of recognised and standard methods. The common fault of this class of book is to be too discursive; to cover too much ground. The small treatise on one subject by an expert like Blair or Ledebur on iron and steel analysis, Brown on gold and silver assaying, Lunge on the alkali manufacture, is the sort of thing one would like to see multiplied.

The writer has no wish to deal unfairly with the under review. It is not uniform in manual character, and if the above criticism applies to certain sections, it is also abundantly evident that other portions have been carefully and conscientiously put together by one who possesses a thorough knowledge of his subject. Moreover, the introduction of mechanical tests, which are too frequently overlooked, is a feature deserving mention. The translator's attention should be directed to the mis-spelling of Stanfurt for Stassfurth, p. 41, Vollard for Volhard, p. 106, and Spiegal for Spiegel, p. 206. The illustrations suffer very much from the rough surface of the paper.

The name of Dr. G. Lunge on the title page of any book, and especially one connected with technical analysis, would command a careful perusal and a thoughtful judgment. It must be confessed that in the present case the author has not done himself justice. Anyone who purchased the volume in the hope of obtaining practical information on technochemical analysis (the translator's rendering of chemisch-technische Untersuchungsmethoden) would, to say the least, be disappointed.

When it is stated that in 128 small octavo pages, in addition to "general operations," and gas, water, and fuel analysis, the analysis of about eighty technical inorganic and organic products is described, further comment seems superfluous. The subject of glycerine, which comes under the section of soap, may be taken as a specimen of the method of analytical treatment.

"Glycerine is found in large quantity only in toilet soaps. The method of determining it is given here, because it must be examined by itself as an individual commercial article, and the glycerine yield of raw fats in the manufacture of stearin must also be determined. The determination is effected either by oxidation with potassium-permanganate solution in alkaline solution, precipitating the oxalic acid formed as a lime salt, and titrating the latter, or by oxidation with normal potassium-dichromate solution, with the addition of an excess of ferrous sulphate solution of known effective value, and then titrating the dichromate solution.”

This occupies half a page, sugar is elaborately treated in four pages, tanning in two and a half, dyeing in as many as seven, mineral oils, vegetable oils, and fats in seven, and so on. The most useful page in the volume is the bibliography of important works of reference at the beginning, though it is scarcely worth the price of the book. J. B. C.

(London : 308.

YEAR

EAR by year this invaluable publication appears with commendable regularity, and year by year its bulk steadily increases, the bulk of the present issue being nearly double that of its predecessor of forty years ago. Hitherto the subscribers have yearly obtained more for their money, but there are limits beyond which even the generosity of a great scientific society cannot go, and it has consequently been decided, although with reluctance, that in future the price of the annual volume must be increased. The bulk of the present volume has been somewhat diminished by printing it on thinner paper than its predecessors; and, although this innovation may have been unavoidable in order to bring the weight within the limits laid down by the Post Office for transmission abroad, it cannot be said to be altogether an improvement, as in places the type shows through in a decidedly obtrusive manner.

a

Whether such radical alteration was really inevitable may perhaps be doubtful, for it is quite evident that a large amount of space might be saved if a uniform plan were adopted throughout the work. For instance, in the section on mammals 385 titles are recorded and their subjects epitomised in a space of forty-two pages, whereas in the section on echinoderms no less than 105 pages are taken up in dealing with 339 papers.

If such prolixity is necessary in the one case, it is equally essential in the other; and, conversely, if the brief mode of treatment will suffice in one instance, it should be adopted in the other. Much space might also be gained, without any loss, in the sections on reptiles and fishes, as well as in certain others.

This lack of uniformity in treatment is, in our opinion, the one point in which this "Record " compares unfavourably with the one issued by the committee of the "International Scientific Record "; and it is high time that it was amended. Surely the editor is strong enough to keep his contributors in hand, and to make them do the work his way and not their own. As an instance of this slackness of the guiding hand we may refer to the fact that in one of the sections the recorder has been allowed to adopt the spelling Meiocene and Pleiocene, which is both wrong (on the supposition that we form our scientific names through the Latin) and pedantic. If any alteration in orthography of this nature were permitted, it should be the substitution of Plistocene for Pleistocene; but if such a change were made i should run through the entire volume.

The comparatively early date at which many of the sections are now sent to press renders it impossible to include so many of the papers for the year to which they specially refer as was formerly the case, but this is a matter of no great moment, so long as such papers make their appearance in the volume for the following year.

Mistakes and omissions there must of course be; but these seem to be few and far between. We notice, however, in the mammal part that Condylarthra has been put in place of Amblypoda, while in the concluding paragraph of the first page of his introduction to the insects the editor is guilty of a blunder which should cause him to be lenient to the shortcomings of his contributors. Whether he can escape blame for errors like the omission of a reference number in the

penultimate line of p. 21 of the mammal part may, however, be open to question.

Taken all in all, the volume is a marvellous production, both as regards accuracy, fulness, and the comparatively early date of its appearance; and the

editor and his staff are entitled to the best thanks of the zoological world. When we have said that the Zoological Record" still stands without a rival,

we have said sufficient.

OUR BOOK SHELF.

R. L.

A Synonymic Catalogue of Orthoptera. By W. F. Kirby. Vol. i. Orthoptera Euplexoptera, Cursoria, et Gressoria. (Forficulidæ, Hemimeridæ, Blattidæ, Mantidæ, Phasmidæ.) Pp. x + 501.

(London: the Trustees of the British Museum, 1904.)

THE value of such a general synonymic catalogue as this work is obvious, but the increased interest which has been taken in Orthoptera in recent years, and the rapidly accumulating mass of literature, has made a complete and systematic catalogue of this order an urgent necessity. The work is upon the same model as the author's previous catalogue of dragon-flies. The species are numbered, though no particular order appears to have been followed; the distribution is given in the margin, and synonymy is attached, although a complete list of references is not given in every case. One of the most prominent features of the list is the conscientious manner in which the author refuses to admit as synonymous such names as to the absolute identity of which he is not personally convinced, resulting in an apparent multiplication of species. Thus, on pp. 30 and 31, We find Spongiphora parallela, S. Therminieri, S. dysoni, and S. croceipennis all entered as separate species, though nowadays there are few who doubt their identity, and fewer still who can discriminate between them. Again, on p. 2, Diplatys gerstaeckeri and D. longisetosa are regarded as separate, although it is impossible to distinguish them. To such an extent does the author carry this principle, that he admits names published with figures only, such as Pygidicrana huegeli, Sharp, and even Ancistrogaster petropolis, Wood, based upon a reference and an illustration in a popular work. But yet he relegates Psalis indica, Hagenb., var. minor, Borm., as a synonym of P. guttata, Borm., although the describer insisted upon the extreme variability of the older known species. But questions of nomenclature and classification are of necessity controversial; many may disagree with the author's arrangement of the genus Labidura, in which a number of insufficiently described so-called species are regarded as valid, only on account of the difficulty of proving their identity with the excessively variable and universally distributed Labidura riparia, Pallas.

Otherwise, changes of well-known names are few. We are glad to see Blatta retained, at the expense of Stylopyga for orientalis and not for germanica.