WHERE ARE THE REAPERS ? COMMON ROOM PAPERS. The Greek Question. EDUCATION DAY BY DAY. OUR LEADERS.-XIII. Edward Thring. THE TEACHERS' FORUM. State Leaving Examinations. SCOTCH EDUCATION.-I. Elementary. By JOHN CLARKE, M.A. THE BOOK AND ITS WRITER. Six Great Schoolmasters. By THEODORE WALKOND, M A. WOMEN AS TEACHERS. By Miss HOSKYNS ABRAHALL. GERMAN LETTER. Local Inspection of German Schools. By HORTICULTURAL TRAINING OF WOMEN. By J. C. MEDD. REVIEWS: Leicestershire. THE NEW "STUDENT'S" STANDARD BAROMETER. (Rd. No. 420,297.) This Instrument has been 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. It appeals especially to Colleges and Schools for Demonstration purposes. 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 wellpolished, solid mahogany board, with plates for attach. ment to wall, opal glass reflectors for reading off, and screws for vertical adjustment. The metal portions are all well bronzed and lacquered, and the scales are silvered brass. We confidently recommend this Instrument for use as 3 "Standard" in Colleges and Schools, private Observatories, and by Gas and other Engineers. Price, complete, mounted as illustrated, £3 7 6 each, or may be had with one scale (either inches or millimetres), and with thermometer on other scale, at same price. NATURE says:-"Provides an accurate instrument at a moderate cost." FULL SIZE STANDARD BAROMETER of same design, bore o'5" diameter, inches and millimetre scales, verniers reading to o'ooz inch and o't m/m, on polished mahogany board with brackets and opal glass reflectors, £7 10 0 Sole Manufacturers and Proprietors of the Registered Design. PASTORELLI & RAPKIN, LTD. 46 HATTON GARDEN, LONDON, E.C. WHOLESALE MAKERS OF ALL KINDS OF METEOROLOGICAL INSTRUMENTS. Contractors to H.M. Government. Estd. 1750. Telegrams," Rapkin, London." Telephone, 1981 Holborn REYNOLDS & BRANSON, LTD., W. H. SMITH & SON'S Sole authorised makers of the STROUD & RENDELL LANTERN, as made by us for the leading Universities. LIBRARY NEW SCIENCE LANTERN for 1905. 186 STRAND, LONDON, W.C., and at the RAILWAY BOOKSTALLS, to which the books are forwarded IT EMBRACES ALL THE MOST IMPORTANT BOOKS, NEWEST & BEST BOOKS ADDED AS PUBLISHED. Over 800 Branches to which Subscribers may be transferred. Terms and Particulars on application. Many Thousands of SURPLUS LIBRARY BOOKS and VALUABLE NEW REMAINDERS OFFERED AT GREATLY REDUCED PRICES. Works of Standard Interest in all branches of General MONTHLY CATALOGUE (150 PACES) FREE ON APPLICATION. 186 STRAND, LONDON, W.C. THE HE old geometrical optics which we used to read at Cambridge was a delightful subject. It would have been a still more delightful subject had examiners set better questions on it. Probably no other branch of mathematics would lend itself so well to the kind of treatment which is now fortunately coming into fashion, viz. the use of graphical and experimental methods. If the German system of Lehrfreiheit prevailed in this country I would rather teach geometrical optics to an elementary class than geometry adapted to modern requirements. This elementary optics, however, bears about the same relation to the optics treated in the first of these books that Newton's deductions from Kepler's laws bear to the planetary theory. The analogy is the more complete in that both the optician and the astronomer have found it impossible to obtain an exact solution by direct methods, and they have therefore been led to employ the method of trial and error in order to obtain successive approximations giving the desired results to closer and closer degrees of accuracy. As Messrs. Czapsky and Siedentopf point out (p. 25), the exact determination of the forms of the refracting surfaces required to produce exact images subject to given conditions has never been effected, except in a few cases, such as the Cartesian oval, in which rays from one focus converge to a point in the other. We therefore take spherical surfaces, and by calculating the various kinds of aberration, show how they may be corrected. It is, however, interesting to learn that the theory of non-spherical surfaces has quite recently been put into practice in the Zeiss works for the first time in the construction of lenses other than large reflectors and refractors for telescopes. It has, in fact, been found possible to correct certain residual aberrations by applying finishing touches to the lenses giving them a slight deviation from sphericity. The analogy between the problems of the optician and the astronomer is made still closer by observing how different specialists have confined their attention to particular kinds of aberration in the one case and of perturbation in the other, and have devised special methods for simplifying the calculation of the corresponding terms. In his preface Dr. Czapski tells us that the present work owed its origin to the demand for a revised edition of his "Theorie der optischen Instrumente nach Abbe," published in 1893. Being unable to undertake the work himself, the idea suggested itself that a better purpose would be served by obtaining the collaboration of a number of joint authors, and that no better body of men could be found for the purpose than the scientific staff of the Zeiss firm. The work has been divided among the seven joint authors as follows:-The first chapter, dealing with the fundamental principles of optics, including the laws of re'raction, the principle of minimum path, and the characteristic function, is contributed by Drs. Czapski and Siedentopf; Drs. König and von Röhr contribute the second chapter, on formulæ of calculation, and the fifth, on spherical aberration, in which latter is contained a complete exposition of Abbe's method of in-. variants and its application to the determination of the ten corrections determined by the problem of Seidel. The chapters on chromatic aberration and on determination of optic systems according to the theory of aberrations (chapters vi., vii.) are contributed by Dr. König alone. The Geometrical Theory of Images after E. Abbe" is the title of the third chapter, by Dr. Mandersleb. In the fourth chapter, by Dr. P. Culmann, on the realisation of optical images, we actually do find our old friend the formula in a position, however, of subsidiary importance. Dr. Löwe contributes a chapter on prisms, while Dr. von Röhr is responsible for the last two chapters, dealing with the breadths of pencils, penetration, brightness of images, and similar matters. The second of these books is of a more elementary and practical character. It contains a general discussion of images formed by small pencils, and illustrated descriptions of the principal optical instruments. The corrections are discussed, but the discussions are less mathematical. The theory of conjugate foci receives fairly full treatment, and among the interesting features which we notice at a first glance, attention may be directed to the series of sections of a pencil of light on p. 24, and the figures of an object and its image on p. 40, where the object is an arrow in a plane through the axis of a lens, and is bisected by the focal plane of the lens. Hand This is the second edition of a book of which the first edition was written for Winkelmann's buch der Physik." Of matter new in this edition, Dr. Eppenstein contributes chapters on screens, on projection apparatus, and on the illumination of objects; chapters on vision, on photographic objectives, and on spectacles are contributed by Dr. M. von Röhr. The perfection to which the manufacture of optical instruments has been brought by the Zeiss firm is well known, and it is also pretty generally realised that the results attained could not have been accomplished by an establishment run on purely business lines by "practical men "falsely so-called. The usual stock form in which the last named class of individual recommends his wares to the public is the stereotyped statement that " The materials used in the preparation of these goods are of the best quality obtain The present books furnish abundant proof that this statement is particularly applicable to the Zeiss instruments in regard to the quality of those materials most essential for the production of good optical apparatus, viz. brains and knowledge of advanced mathematics. G. H. BRYAN. AMERICAN CYTOLOGY. Fecundation in Plants. By David M. Mottier, Ph.D. Pp. viii+187. (Washington Published by the Carnegie Institution, 1904.) Contributions to the Knowledge of the Life-History of Pinus, with Special Reference to Sporogenesis, the Development of the Gametophytes and Fertilisation. By Margaret C. Ferguson, Ph. D. Pp. 153. (Washington: Published by by the Washington Academy of Sciences, 1904.) MR. R. MOTTIER'S "Fecundation in Plants" gives to those who are interested in cytology an account of the phenomena of fertilisation throughout the vegetable kingdom, written by one who has carried on investigations in several branches of the subject with success. His practical acquaintance with his subject confers even on his descriptions of the investigations of others a freshness which makes his work a pleasure to read. The first chapter is perhaps the most generally interesting. In it he gives an account of some of the vexed problems of karyology which are at present calling out so much controversy among cytologists. Among these problems may be mentioned the existence of centrosomes, the homology of centrosomes and blepharoplasts, the nature of synapsis, the significance of the sexual process, and the numerical reduction of chromosomes. The author's method of discussion is candid. He avoids being dogmatic in expressing his own views, although he criticises somewhat severely the observations of others. He holds that centrosomes and centrospheres do not occur in plants higher than the liverworts, and are, indeed, only well established in a few of the Thallophyta. It is remarkable that he does not allude to the possibility that the radiations at the poles of mitoses may be in part artefacts produced by the fixing agents. He considers Belajeff hasty in coming to the conclusion that the centrosome is the homologue of the blepharoplast; but he admits later on that certain "facts lend encouragement to the belief that centrosome and blepharoplast may be homologous structures." Mottier regards synapsis as due in a large measure to the action of reagents. He accepts Strasburger's theory of the numerical reduction of chromosomes as a good working hypothesis, and he holds now that there is no evidence for Weismann's "reduction " to be found in the mitoses of plants. His candid expression of doubt as to the persistent individuality of the chromosomes preserved through the successive mitoses-so often assumed, though almost involving a miraculous resurrection—is typical of his attitude of independence. The succeeding chapters give an account of fertilisation in types taken from the various subdivisions of the vegetable kingdom. These descriptions are most useful in bringing together what is scattered the sporadically through botanical literature into compass of a short, well written book. The work is illustrated by blocks in the text, which show in a satisfactory manner the points to be brought out. Miss Ferguson's memoir has a more limited scope, but this allows her to devote more space to her own researches, which have been very extensive in the cytology of the spore-production of conifers. It is quite remarkable to see how two cytologists, writing almost simultaneously, can hold so divergent views on fundamental subjects. While Mottier sees in the fusion of sexual nuclei the blending of two lines of descent, Miss Ferguson's researches lead her to believe that no fusion-nucleus, combining the paternal and maternal hereditary substances, is formed. Rather the processes of mitosis allow these to be kept apart during the life of the offspring, and the "reduction " or qualitative division occurring some time during the life-cycle secures that the gametes shall be "pure. It is evident that the later writer is concerned with the relation of mitosis to Mendel's views rather than to Weismann's hypothesis. With regard to synapsis, Miss Ferguson believes it to be a normal stage in heterotypic mitosis. Another point of difference is the mode of origin of the double chromosomes of heterotypic mitosis. Miss Ferguson finds confirmation in her preparations for the view (first published by the writer of this review in 1896, Proc. Roy. Irish Acad.) that the two arms of the chromosomes are approximated pieces of the nuclear thread, and do not arise by longitudinal cleavage as Mottier believes. This interpretation seems to be gaining ground, and the Louvain school, once so much opposed to it, has recently accepted it, putting the folding back, however, to the synaptic stage. The reviewer's investigations seem to suggest the possibility that two distinct foldings take place, one during synapsis and another between that stage and the differentiation of the chromosomes. Whatever views are held on these disputed matters, all cytologists are indebted to the author for her beautiful drawings, which are reproduced in a series of twenty-four plates. There is no doubt that the publication of these two memoirs, the one by the Carnegie Institution and the other by the Washington Academy, will be of much service to those engaged in cytological research. H. H. D. : PHYSICAL RESEARCH AT LEYDEN. Het Natuurkundig Laboratorium der Ryks-Universi teit te Leiden in de Jaren 1882-1904. Gedenkboek aangeboden aan den Hoogleeraar H. Kamerlingh Onnes, Directeur van het Laboratorium, by gelegenheid van zyn 25-jarig Doctoraat op 10 Juli 1904. Pp. viii+288. (Leyden Eduard Ydo, 1904.) HIS volume was prepared by colleagues and pupils of Prof. Kamerlingh Onnes, of Leyden University, and presented to him on the twenty-fifth anniversary of his receiving the degree of Ph.D. It differs in character from the usual collections of scientific papers which it has become the fashion on the Continent to present to eminent men of science on THIS similar occasions. Since 1882 Prof. Onnes has been director of the physical laboratory at the University of Leyden, and the book gives a description of the growth of the institution since his accession to the directorship, of its present condition, and of the work carried out by himself and by his pupils under his supervision. In a sense it is a matter for regret that by the nature of the case he himself had to be excluded from the list of contributors; on several of the subjects dealt with it would be interesting to have the director's personal views. After an eloquent dedication from the hand of Prof. Bosscha, we find in the first chapter, compiled by Prof. Haga and others, a detailed description of the laboratory and of the more important machinery and fittings, particularly those belonging to the "cryogenic" department, to which Prof. Onnes has devoted most of his personal labours; the low temperature baths prepared here are extensively used throughout the laboratory for various researches. In an appendix to this chapter Dr. Siertsema gives an interesting account of the training school for apprentice mechanics instituted by Prof. Onnes in connection with the laboratory. This institution is probably unique; it was started in 1886 with one pupil, and the number has risen steadily until this session of researches on Hall's phenomenon in bismuth at various temperatures down to the boiling point of oxygen, measurements of the dielectric constant of liquid oxygen and liquid nitrous oxide, and of the absorption of Hertz vibrations by salt solutions. A detailed account of all the research work is published regularly in the Communications from the physical laboratory at Leyden, the issue of which was commenced in 1892, but the present papers give a useful general summary of the work carried out, presented in a manner which should make it intelligible to the uninitiated. The volume bears ample testimony to the success which has attended Prof. Onnes's manifold labours for his laboratory, which owes to him its position as one of the best known institutions of its kind. It is well illustrated, and contains as a frontispiece a striking likeness of Prof. Onnes, apparently after a drawing. PRACTICAL SILICATE ANALYSIS. Manual of the Chemical Analysis of Rocks. By H. S. Washington, Ph.D. Pp. ix + 183. (New York: Wiley and Sons; London: Chapman and Hall, Ltd., 1904.) Price 8s. 6d. net. no less than thirty-three boys are receiving systematic Flate years greatly increased attention has been instruction in the various mechanical arts, with the object of qualifying themselves as instrument makers, glass-blowers, electricians, and for similar professions. The boys are supposed to assist to a certain extent in the routine work of the laboratory and earn corresponding small wages, while in the evening they have to attend classes in the municipal technical institute. A better training for the purpose could hardly be imagined, and one is not astonished to learn that after the completion of the three years' course the boys appear to be much in request in laboratories and various engineering and technical works. In chapter ii. thermodynamical investigations are reviewed; Prof. van der Waals gives an account of Prof. Onnes's researches on thermodynamical surfaces, Prof. Kuenen writes on the phenomena of condensation of binary mixtures, and there are further articles on accurate isothermals of gases, on the construction of models of surfaces, and on capillarity and viscosity of liquids up to the critical region. The third chapter, edited by Prof. Lorentz and others, is devoted to optical and magneto-optical work; here we find a discussion of experiments on the reflection of light by mirrors, on the magnetic rotation of the plane of polarisation in gases, liquefied gases and other liquids, on the influence of pressure on the rotation of sugar solutions, on the reflection of light by magnetised mirrors (Kerr's phenomenon), and an account of Zeeman's discovery of the modification in spectra by magnetic forces. The phenomenon discovered by Egoroff and Georgiewsky, that a sodium flame placed in a magnetic field emits partially polarised light, was investigated by Prof. Lorentz himself, and appears to be closely connected with Zeeman's phenomenon. In the last chapter Prof. Zeeman gives a description directed to the chemical investigation of rocks, and the science of petrology has been enriched by many excellent analyses. Among these the work of the United States Geological Survey deservedly holds the highest place, both on account of its abundance and its thoroughness. The present treatise arises from an endeavour to make the methods used by Clarke, Hillebrand, and other chemists in the United States laboratory available to all workers. It is excellently clear and detailed, and though the experienced analyst will not find in it much that is not already published in more succinct form in the official Bulletins of the Survey, he will glean a few details of manipulation and discussions of the bearings of chemical petrology that will at any rate repay perusal. The author intends his book to be used mainly by the rather numerous class of geologists and petrologists who combine a fair knowledge of chemistry with a desire to make their own rock analyses. Undoubtedly this is a far more satisfactory proceeding than, as is usually done, to have the analyses executed by some analyst who has no special knowledge of the intricacies of this part of practical chemistry, and follows methods which are discredited or discarded. In any case such a worker will do well to place himself, for a time at least, under some teacher who is thoroughly at home in the subject; we hope that this book will not stimulate the production of analyses of rocks by students in course of training. Much of the worst analytical work with which chemical petrology is burdened has been executed in that way. If it helps to spread the knowledge of the methods used by Clarke and Hillebrand this book will do much good, as it is desirable that these should henceforward be recognised as standards, from which any important departure should be notified when the results are published. In a few respects Dr. Washington has simplified the standard American procedure. We think this is wise, and, while we endorse his opinion that only the best work should be aimed at, we do not think that this means that the very elaborate American analyses should be emulated by the ordinary worker. From twenty to twenty-five elements are usually sought for by the American chemists, and nearly one-half of these may be present in less than 1 per cent. of the total rock. Such analyses look exceedingly well on paper, but require the greatest experience and manipulative dexterity if they are to be trustworthy. Moreover, their value is as yet not beyond question. Certainly an analysis in which ten or twelve elements are determined as exactly as possible is more welcome than an analysis which is more elaborate but less accurate. We notice that the author discourages the routine execution of duplicates. No doubt this is right; they take up much time, and may be useless or misleading; it is better for the experienced chemist to occupy himself in the most thorough testing of his reagents, the purity of which is never above suspicion. Still, there can be no doubt that duplicate analyses do show how far it is possible for the results to vary when two samples of the same powder are analysed. They help to check any exaggerated confidence in analytical refinements. In this respect it would be interesting to know what are the probable limits of error in analyses executed by the methods given in this book. The author gives his opinion (apparently not founded on any special investigations), and it strikes us that he is more sanguine in this respect than the majority of experienced silicate analysts in Britain or on the Continent. OUR BOOK SHELF. Application of some General Reactions to Investigations in Organic Chemistry. By Dr. LassarCohn. Translated by J. B. Tingle, B.A. Pp. 101. (New York: Wiley and Sons; London: Chapman and Hall, Ltd., 1904.) Price 4s. 6d. net. IT would be difficult to say with what object and for what class of readers this little volume (it is scarcely more than a pamphlet, and may be read in an hour) was written. Yet anyone engaged in the practical pursuit of organic chemistry cannot fail to be interested in it. One may say roughly that the book treats of the unsystematic part of organic chemistry, i.e. of the ordinary reactions which do not succeed, and how they may be made to do so. Without always offering a very satisfactory explanation of the causes of success or failure, for the terms "protective influence" and "contact action" are after all merely names, the author points out how an apparently unimportant modification may affect the whole course of a reaction and convert an unprofitable method into a successful or commercially lucrative one. Incidentally, he urges the systematic study of these anomalous reactions. As an example may be mentioned the well known fact that the accidental introduction of a few drops of mercury into the experimental vessel, in which the preparation of phthalic acid from naphthalene was in progress, rendered the operation and consequently the production of artificial indigo a success. As a rule the difficulties encountered by the anomalous behaviour of organic compounds are met not by more drastic treatment, but by milder reagents. In this connection it is suggestive that the funda mental reactions of living matter which embrace oxidation and reduction of a far-reaching kind, as well as synthetic processes more complex than anything achieved in the laboratory, are all effected at ordinary temperatures and with the mildest reagents. It follows, therefore, that the more closely organic chemists succeed in imitating these conditions the more surely will those mysterious contact or fermentation problems usually associated with living protoplasm, but not unknown in the laboratory, approach solution. J. B. C. A Further Course of Practical Science. By J. H. Leonard and W. H. Salmon. Pp. ix+224. (London: John Murray, 1904.) Price 25. In this book the principles of natural science are taught and enforced in a scientific manner by means of a course of experimental work, simple in character, but involving quantitative measurements, and carried out personally by the student. To begin with, lengths are measured with an ordinary rule, and tests are made in order to find out the limits of accuracy within which the measurements may be relied on. measurements serve as an introduction to "physical arithmetic," or simple arithmetical computations specially suitable for dealing with numbers which are avowedly only approximately correct. Then follows a chapter on elementary mensuration involving the estimation of angles, lengths, areas, and volumes, the balance very wisely sharing in this work. These Experiments are devised to illustrate some of the fundamental properties of matter, such as those of indestructibility, inertia, porosity, ductility, &c. The next six chapters deal with mechanics, the subjects including uniform linear acceleration, Newton's laws, relative motion, statical equilibrium of uniplanar forces, and simple machines. This difficult section is not treated in a very satisfactory manner. The method is too deductive, the experiments are some what scanty and not very well chosen. Thus there is no direct verification of the fundamental principle of the conservation of momentum. Vectors, though introduced, are not made sufficiently prominent, and in the so-called "simple machines" it seems rather antiquated to find the three kinds of levers, the three systems of pulleys, the wedge, &c., introduced. In the concluding chapters relating to the properties of liquids and gases, and the nature of heat, the authors are happier in their treatment, notwithstanding an occasional looseness in the statement of a principle. The book deserves to be very favourably received, and teachers will find that arrangements have been made to facilitate the purchase of the apparatus necessary for conducting the experiments. Die drahtlose Telegraphic. By Dr. Gustav Eichhorn. Pp. x+256; numerous figures. (Leipzig: Veit and Co.) Price 5 marks. THIS is an elementary exposition of the principles and practice of wireless telegraphy with especial reference to the systems developed by Dr. Braun. It is evidently intended to enable a practical man to become acquainted with this method without, at the same time, any attempt being made to give such a complete |