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RADIOTELEGRAPHY

THE TANTALUM DETECTOR

(Walter's Patent-Latest Pattern)

is the most sensitive for EXPERIMENTAL and COMMERCIAL work.

q Prof. J. A. FLEMING, F.R.S., says:"One of the best and simplest of these imperfect contact oscillation detectors is the tantalum-mercury of L. H. Walter."

q Prof. R. A. FESSENDEN says:

"Some recent tests which I have made substantiate the inventor's claims . . . it responds very strongly indeed. in fact, more powerfully than any detector with which I am acquainted."

Supplied only by

TELEGRAPH & TELEPHONE
INSTRUMENTS, LTD.,

25 Victoria Street, London, S.W.

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CONSTERDINE & ANDREWS' ARITHMETIC.

SET "A," 120 models (cube, square prism, prism with oblong base, cylinder). Price £1 5 0.

SET "B," 75 models (prism with parallelogram as base; Triangular prism, Hexagonal prism; Cone; Pentagonal pyramid). Price 16s. 6d.

Average size of above 8 cm. cube.

Snow Crystal Set of Mathematical Instruments, as figure. Price per dozen, £1 15 0.

Descriptive List on application.

List of Special Apparatus for Mackenzie's Theoretical and Practical Mechanics and Physics post free on application.

14 COMMERCIAL ST., LEEDS.

NOW READY, xvi + 432 pages. 8s. 6d. net.

A TEXT-BOOK OF

EXPERIMENTAL PSYCHOLOGY

By CHARLES S. MYERS, M.A., M.D., Lecturer in Experimental Psychology in the University of Cambridge, Professor of Psychology in King's College, University of London.

FROM NATURE, JULY 29, 1909 :

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This book supplies a want which has been long felt by both students and teachers. Until now there has been no text-book to meet the special needs of those attending a course of instruction in experimental psychology. There have been books on psychology written on an experimental basis which have differed little, if at all, from others not so characterised, and there have been handbooks for the laboratory, notably that of Titchener, but there has been no book which attempted to give in reasonable compass a general account of experimental methods and of the results which have been gained by the experimental movement in psychology. Such a book was needed for two classes of persons, for those definitely committed to the study of the subject, and for the large class of people who know that experimental psychology exists but do not know what it means.

"It may be said at once that for each Prof. Myers's book will be of the greatest service. It gives a concise and yet clear account of what has been done by means of experiment in psychology, and it is surprising to find so vast an amount of information in a book of the size. At the same time, there has been admirable judgment in the selection of the material and in the discussion of the many thorny topics in which the science at present abounds."

London: EDWARD ARNOLD, 41 & 43 Maddox Street, W.

THE "STUDENT'S"

STANDARD BAROMETER.

(Registered Design No. 420,297.)

Designed to meet the requirements of Students and others who find the need of a Barometer which will give exact readings, and cost but a moderate sum.

Used for demonstration purposes in all the principal Science and Technical Colleges, and adopted by the L.C.C. for use in their Classes.

The construction is on that of the well-known "Fortin" principle. The level of the cistern mercury is reducible to zero, in exactly the same manner as in the more expensive forms. The diameter of the mercurial column is 25 inch, and affords a bold, well-defined reading. The scales, by means of the double vernier, are capable of being read to or inch and 1 millimetre. It is mounted on a well-polished, solid oak or mahogany board, with opal glass reflectors for reading off, and screws for vertical adjustment. The metal portions are all well bronzed and lacquered, and the scales are opal glass. A thermometer, graduated on stem F. and C. scales, is fitted to the brass frame.

We confidently recommend this Instrument for use as

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a Standard" in Colleges and Schools, private Observatories, and by Gas and other Engineers.

Price, complete, mounted as illustrated,

£3 7 6.

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HERE is required no little courage on the part of both writer and publisher to issue a book with this forbidding title, which to the layman brings memories of the nauseous ransom paid for release from

disabilities, and to the medical man renews the griefs

on

of "lectures on materia medica at 8 o'clock
a winter's morning" which Darwin found "some-
thing fearful to remember." To those who are not
repelled by the exterior, however, we can promise
much enjoyment from the perusal of this volume,
which is written with the same distinction of literary
style and with the same felicity of illustration as
marked the author's "Principia Therapeutica." He
writes for the educated layman, and, avoiding the
technical pitfalls with which medicine is so bestrewn,
gives a clear view of the principles on which treatment
must rest. Commencing with a short historical
review of the deductive medicine of the " systems,'
among which he places that curious survival
homœopathy, he passes quickly to the definition of
his subject, noting by the way the etymological con-
nection between drug and dry, and then discusses the
general aim of drug-giving and the grounds on which
it is based. Here, as throughout, the author draws
many analogies between familiar physical phenomena
and the action of drugs, and attempts to dispel the
mysticism in which therapeutics is still involved to
the lay mind.

The mental effect of treatment as apart from the

when the environment of the subject is changed and the possibility of indulgence is restricted, so that the impulses to satisfy the craving are not aroused, while those tending to develop control gain ascendancy. The difficulty arises on return to the habitual environment, when the old impulses throng through the well-beaten paths, and the feeble, newly-acquired, guardian impulses are not aroused by the surroundings. One form of drug habit which finds no mention we should like to have seen discussed from the author's standpoint, the most prevalent, and not least pernicious of them all, that of self-drugging with all sorts of nostrums, which becomes an obsession with many of the laity, and is often accompanied by profound distrust of the medical profession.

The drink problem receives some attention, and the solution suggested is not legislation and restriction so much as education in self-control. The shortcomings of the recent Sale of Poisons Act are subjected to criticism; but should we have a Sale of Poisons Act at all? Might we not trust to education here also? On p. 231 it is stated that morphia may be detected in the urine in subjects of the opium habit, which is not in agreement with ordinary experience, and the direct inheritance of drug habits, as apart from the inheritance of the mental weakness which underlies these, requires

further confirmation.

EUCLID'S ELEMENTS IN ENGLISH. The Thirteen Books of Euclid's Elements. Translated from the Text of Heiberg, with Introduction and Commentary, by T. L. Heath, C.B.

3 vols. Vol. i., Introduction and Books i.-ii., pp. x+424; Vol. ii., Books iii.-ix., pp. 436; Vol. iii., Books x.-xiii. and Appendix, pp. 554. (Cambridge: University Press, 1908.) Price 21. 2s. net.

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placebo are dealt with at some length. Drugs are thrown into large classes as nutrients, incitants, depressants, alteratives, antiseptics, and sedatives, which may perhaps find justification in treatises of this kind, but which it is difficult to reconcile with the canons of modern pharmacology. The newer methods of therapeutics, such as organotherapeutics and as organotherapeutics and serum therapeutics, are the subjects of an interesting chapter, in which they are claimed as the modern developments of ancient theory and in no way dis

tinct in character from other forms of medication. Is not the theory underlying the use of thyroid extract the same as that which suggested the administration of pepsin, and is not the newest vaccine a direct descendant, even in terminology, from that of Jenner?

A third of the book is devoted to the habitual use or abuse of the narcotic and soporific drugs, such as opium, alcohol, and chloral, and to the treatment of the consequent "drug habits." Here the importance of re-building the character and self-control of the victim is insisted on, and no medicinal treatment is considered of value except in a purely subsidiary and incidental way. Some support is given to the mental treatment of these cases, but its difficulties and drawbacks are recognised. Improvement is often obtained

UR island is the last home of ignorant Euclidolatry; argal, a German scholar has been allowed to edit, and a German firm to publish, the best and only critical text of Euclid's works. Our ancient universities maintain compulsory Greek; argal, Dr. Heath has thought it necessary to undertake, in addition to his commentary, an English translation of the text. Accepting these facts as part of the eternal fitness of things, those who can beg, borrow, or buy these three handsome volumes will be able to learn the actual contents of the "Elements," the history of their propagation and influence on mathematical study, and their relation to Greek science and philosophy in general. Dr. Heath has been so long a devoted student of Greek geometry that he is able to give his readers a very good idea of its developments and peculiar limitations; his commentary seems to cover every point of real interest, and he has rightly given, by way of comparison, some account of the modern theory of irrationals.

Naturally, the definitions and postulates receive a good deal of attention. The definition of a straight line is translated "a straight line is a line which lies evenly with the points on itself," and the same rendering of è rov is given in the definition of a plane. Readers of the notes on these definitions will probably agree with the editor that è rov, thus applied,

was an obscure phrase even to a Greek, and that it was meant to refer to what we may call the indifferent distribution of points and lines on a line and a plane respectively. At any rate, Proclus's explanation is clearly wrong, though it very likely contains the substance of what a teacher would often say in commenting on Euclid's text.

Another very interesting note is that on the Greek notion of "angle." As this included curvilinear angles, it led to a variety of discussions and some paradoxes; for example, taking a semicircle AMB and a tangent BT at one end of the diameter AB, it was argued that the angle at B between the circle and diameter is less than the rectilineal angle ABT, because BT is outside the circle, while, on the other hand, any acute rectilineal angle can be proved less than the curvilinear angle in question. However (p. 176, bottom), there is some evidence of a way of looking at angles such as we should now express in terms of the differential calculus.

To the famous postulate 5 (generally referred to as the 11th axiom) eighteen pages are devoted. Here it must suffice to say that sufficient references are given to the principal authorities on the theory of parallels and non-Euclidean geometry, and that attention is properly directed to the work of the Jesuit Saccheri.

The books least familiar to students are, of course, the arithmetical books (vii.-ix.) and Book x. With regard to the former, Dr. Heath has given diagrams consisting of straight lines, just like those in Book v.; this is rather misleading, and it would surely have been better to give rows of dots, or, at any rate, graduated straight lines to the same scale. In this part of the work, Dr. Heath gives algebraical paraphrases of the less obvious propositions; these will be found very helpful to those not familiar with Greek methods of reasoning.

of the Elements

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As De Morgan said long ago, the most remarkable (and in some ways most characteristically Greek) book is the tenth. If we turn its propositions into algebra, we find that they contain an exhaustive classification of a certain set of irrationals (or irrational ratios), all, of course, constructible from a given line by means of rule and compass. Dr. Heath, in his introductory note, gives the irrationals in question in an algebraic form, which is perhaps the best suited for comparison with the propositions, but hardly so neat as De Morgan's in his article ("Penny Cyclopædia ") on "Irrational Quantities," which is still worth careful reading.

It should be mentioned that there is an appendix containing the spurious Book xiv. (by Hypsicles), and a note on the so-called Book xv., two elaborate indexes, and a beautiful facsimile of a page of the Bodleian MS. D'Orville 301.

Those who are really interested in Greek geometry will be deeply grateful to Dr. Heath for putting together, in such an attractive form, such a large amount of historical information, and thus saving students from an immense amount of toilsome research. Finally, the excellence of the diagrams, especially in Book xiii., should not be overlooked. G. B. M.

HYPNOTISM AND OCCULTISM.

Hynotism, including a Study of the Chief Points of Psycho-therapeutics and Occultism. By Dr. Albert Moll. Translated from the fourth enlarged edition by A. F. Hopkirk. Pp. xvi+610. (London and Felling-on-Tyne: The Walter Scott Publishing Co., 1909.) Price 6s.

THIS book is a translation from the fourth edition of the original work. The author presents his readers with a survey of all that is most important in the whole province of hypnotism, and indeed has left little unsaid which could be of any value. An opening chapter on the history of hypnotism indicates the gradual progress of the science from the stage in which it was almost hopelessly mixed up with superstitious quackery, through periods of neglect on the part of the scientific world, to the era, which is even now only dawning, in which the subject is submitted to the strictest critical examination of physiologists and psychologists. The literature that has grown up round the subject is enormous, and its volume almost daily increases.

In

Dr. Moll's work is not one which is likely to appeal to the general reader, and, indeed, we are of opinion that this is one of its greatest merits. In this country hypnotism has too long been a subject in which a certain class of mind has taken an interest alternatively to spiritualism, "Christian Science," or other occult system of the day. To such, a carefully attentive and balanced criticism is positively repellent, and it is, unfortunately, in this class that hypnotism has hitherto had its vogue. Dr. Moll deals in very considerable detail with the symptoms of hypnosis. deed, by far the longest chapter of his book is devoted to a minute account of the psychological, physiological and even anatomical changes which may be noted during, or as a result of, hypnosis. The various explanations which have from time to time been put forward as to the hypnotic state are subjected to searching analysis, and the confident assertions of many of them are shown to have no foundation. What we know about mental processes is confined to a few concomitant phenomena, while the real nature of such processes appears for ever debarred us, and to our author the endeavours of some investigators to explain mental processes by means of our present knowledge of the central nervous system indicate a disquieting tendency to overestimate the gifts of physiology. It is, at any rate, plain that authorities take up diametrically opposite sides in their hypotheses as to the nature of the hypnotic phenomena.

The medical and legal aspects of hypnotism are dealt with at much length, and an important conclusion that emerges from the consideration of hypnotism from these points of view is that its practice should be confined to those who are properly trained in the diagnosis of the affections which it is sought to treat. To hypnotise those who should not be hypnotised, and to seek to cure disease which is not amenable to such treatment, is to bring hypnotism into disrepute and to wrong the sufferer. Dr. Moll winds up his work with a chapter upon occultism, not because there is any in

as

ternal affinity between hypnotism and occultism, but characteristics; interpoles; the Thury system because the two subjects are often mentioned together, applied to the Moutiers-Lyon installation; relay for a connection determined by their historic develop-field regulation; mechanical analogy of alternating ment. We wish that all enthusiastic investigators of currents; a number of obsolete alternators; some the occult could be induced to peruse this part of the modern alternators; form factor; oscillograms; vector book. With a candid admission of the depth of our diagrams; currents in branch circuits; resonance; ignorance, our author asserts that we have no right stationary waves in the antenna of a wireless station; flatly to refuse to recognise any domain of research. the Slaby-Acro-Braun system of wireless; DobroYet if the conditions of research into the phenomena volsky's balancing transformer for three-wire system; of occultism be severe, and if none of the assertions electric bells; Rhumkorff interrupter; Wehnelt of occultists be accepted without proof, there is, interrupter; selenium cell; buzzer; maximum cutaccording to Dr. Moll, no single series of experiments out; high-frequency arc; wireless telephony; power that carries with it a convincing proof of the reality of electric currents. of occultistic phenomena. We can warmly recommend this work to our readers as a thorough exposition of an abstruse subject.

ELECTRO-TECHNICS.

C.

Einführung in die Elektrotechnik. By Dr. Heinke. Pp. xviii+501. (Leipzig: S. Hirzel, 1909.) Price 13 marks.

A1

T a first glance this seems a very interesting book, but a closer study of its pages produces a feeling of mental fatigue, not to say impatience; and this is probably due to the fact that many obvious points are set out at great length whilst really important or difficult matters are passed over with tantalising brevity. Thus the author gives us many pages on the calculation of the current in a circuit containing inductance and resistance, or capacity and resistance, but the subject of single-phase commutator motors is dismissed in exactly two and one-third pages.

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After a long-winded introduction, in which the author develops his ideas as to what should be taught at a technical high school and what constitutes the real difference between the mere technical man and the scientific engineer, we find a chapter which a less pedantic writer would have simply headed "mechanical analogies," but which bears the title Conceptions of a Mechanical Nature to facilitate the Mental Connection between all Basic Electromagnetic Phenomena." The fifty-odd pages in which the author develops his analogies are very interesting, but they can only be read with advantage by persons who are already well acquainted with the subject. A beginner will find the analogy more difficult to understand than the electrical phenomenon

itself.

Next follows a chapter entitled "Pressure Producers" (German Spannungserzeuger), and in this we find the old-fashioned frictional machine (but not the Wimshurst), Armstrong's experiment, primary batteries, thermopiles, and the dynamic generation of E.M.F. discussed. The latter leads to the following chapter, on "The Technical Production of Electrical Energy." This occupies some 200 pages, and contains a most bewildering collection of all possible things either directly or very remotely connected with dynamos. A few titles of the matters treated will suffice to show how varied is the character of the subjects collected under this head :-mechanical details of armature; commutator and field system;

The fifth chapter deals with the application of electricity, and here we get also a great variety, such as Geissler tubes, lifting magnets, bells, telephones, transformers, motors, the Kjellin furnace, a catalogue picture of a chain-welding machine, glow lamps, are lamps, secondary batteries, a load diagram of a central station, switchboard diagrams for D.C. and A.C. stations. The final chapters deal with measuring instruments, cables and overhead lines, switches, and accessory apparatus. The grouping of all these different matters as adopted by the author may be logically right, but it is not convenient for the reader; it is also irritating to find a page or so of elementary mathematical treatment interleaved between catalogue pictures of some firm's apparatus, whilst the important features of the thing illustrated are hardly mentioned. The book has interesting parts, but to find them the reader must know a good deal of the subject; and even then the search will be rather troublesome, as there is no index. GISBERT KAPP.

OUR BOOK SHELF.

(1) Leitfaden der Tierkunde für höhere Lehran-
stalten. By Dr. K. Smalian. IV. and V. Teilen.
(Leipzig: G. Freytag, 1909.) Price 1.80 marks.
each.
Unterrichtswerk
(2) Naturwissenschaftliches
für
höhere Mädchenschulen. By Dr. K. Smalian and
K. Bernan. I. Teil. Pp. 50; illustrated. (Leipzig :
G. Freytag, 1909.) Price 1.20 marks.
(1) WITH the two parts referred to under the title
of the work first quoted, Dr. Smalian brings to a
conclusion his "Leitfaden," of which the earlier parts
have been already noticed in NATURE. The fourth
part, which is devoted to the Arthropoda, is stated
to be for lower third form teaching (Lehrstoff der
other invertebrates, is intended for upper third form in-
Untertertia), while the fifth part, dealing with the
struction (Lehrstoff der Obertertia). Whether the parts
intended for the higher forms are considered to com-
prise more difficult zoology than those for the lower
grades is not very easy to decide. As regards style
of treatment, the two parts before us seem to follow
very much the lines of their predecessors, and contain
a vast store of information, conveyed in a very con-
densed and concise manner, this technicality of the
text being in some degree relieved by the coloured
plates, the subjects of which are well selected, and
illustrate the life-history of a number of species.

in accordance with the requirements of a new scheme
(2) This text-book has been written by the authors
of instruction authorised for higher grade girls'
schools in Prussia, and in order to conform exactly

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