Imagens das páginas
PDF
ePub
[blocks in formation]

MANUFACTURING PROCESSES. By BERTRAM BLOUNT, F.I.C., & A. G. BLOXAM, F.I.C. CONTENTS.-Sulphuric Acid Manufacture-Manufacture of Alkali and its By-products-Destructive Distillation-Artificial Manure Manufacture -Petroleum-Lime and Cement-Clay Industries and Glass-Sugar and Starch Brewing and Distilling-Oils, Resins, and Varnishes-Soap and Candles--Textiles and Bleaching-Colouring Matters, Dyeing, and Printing -Paper and Pasteboard-Pigments and Paints-Leather, Glue, and SizeExplosives and Matches-Minor Chemical Manufactures-BibliographyIndex.

JUST READY. In large Crown 8vo. Fully Illustrated. GLUE, GELATINE,

And their Allied Products.

By THOMAS LAMBERT, Analytical and Technical Chemist. CONTENTS.-Historical-GLUE-GELATINE-Size and Isinglass-Treatment of Effluents produced in Glue and Gelatine Making-Liquid and other Glues, Cements, &c.- Uses of Glue and Gelatine Residual Products-Analysis of Raw and Finished Products-APPENDIX-INDEX. JUST OUT. In Handsome Cloth, with 59 Illustrations.

6s. net.

SMOKE ABATEMENT,

A Manual for the Use of Manufacturers, Inspectors, Medical
Officers of Health, Engineers, and others.
By WILLIAM NICHOLSON,

Chief Smoke Inspector to the Sheffield Corporation.
CONTENTS.-Introduction-General Legislation against Smoke Nuisance
-Local Legislation-Foreign Laws in regard to Smoke Abatement-
Smoke Abatement-Smoke from Boilers, Furnaces, and Kilns-Private
Dwelling-house Smoke - Chimneys and their Construction - Smoke
Preventers and Fuel Savers-Waste Gases from Metallurgical Furnaces -
Summary and Conclusions-Index.

[subsumed][subsumed][merged small][graphic][merged small][merged small][graphic][merged small][merged small][merged small][merged small][merged small]

The newest and best books of popular interest are added as published.

The books are delivered to the Bookstalls to Subscribers' orders, carriage paid.

Over 800 branches to which Subscribers can be trans. ferred.

Special Travelling Subscriptions entitling Members to exchange at any branch without previous notice. Terms on application.

Books exchanged by Parcels Post, Rail, or other means from the Head Office to any part of the United Kingdom. Boxes supplied gratis.

Prospectus and list of recent books in circulation and any other information can be obtained upon application. A catalogue of Surplus Library and New Remainder Books, offered at greatly reduced prices, is published monthly, and supplied gratis on application.

HEAD, 186 STRAND, LONDON, W.C.

OFFICE:

THURSDAY, SEPTEMBER 14, 1905.

ASTRONOMY FOR TRAVELLERS. Handbuch der geographischen Ortbestimmung für Geographen und Forschungsreisende. By Dr. Adolf Marcuse. Pp. x+342+2 charts; illustrated. (Brunswick: Friedrich Vieweg und Sohn, 1905.)

A

SHORT preface by the author tells us that this book is designed, in the first place, to give assistance to geographers and explorers, to aid students of the mathematical sciences and pupils in the higher schools, and to serve as an introduction to those parts of astronomy which, since they are concerned with the determination of time and of position on the earth's surface, have an important influence on everyday life. One does not expect, therefore, a description or an explanation of the nicest details that lead to the greatest accuracy, but rather the exhibition of the general principles on which the determination of coordinates depends; and on the whole this ground is fairly well covered, both from a theoretical and practical point of view. But when an author poses as a teacher, we are apt to examine his book a little closely, to see if he has shown any sign of clearly apprehending the difficulties that learners and pupils encounter when attacking a new subject, and made any adequate effort to remove these difficulties. There is no evidence of any particular care in this direction, though, of course, it is no easy matter to detect beforehand where the pitfalls and misconceptions on the part of the pupil will arise, and points that seem to one teacher to demand lengthened explanation or further illustration do not present themselves in the same way to the judgment of another expert.

a

But there is another test which may be more safely applied. Are any matters introduced which give needless complexity, or delay the continuous progress of the work? In this respect we think the author is not altogether blameless. For instance, the section on "probable error" and the solution of equations by the method of least squares seems on this ground out of place. The subject in the space given to it is not, and cannot be, treated exhaustively; it must leave but a very hazy notion in the student's mind, and the application of the theory is not wanted in the discussion of the rough results which are derived from the instruments that are employed. Similarly, what has a traveller dealing with approximate values of latitude and longitude to do with the small variations arising from the motion of the Pole? It seems a little inconsistent to suggest a degree of accuracy in the final results which cannot be realised with the particular means adopted.

If these are details into which it would have been better not to have entered, there are, on the other hand, omissions, or at least what appear to be omissions, to which some reference should have been made. Thus, by way of illustration, we may mention the absence of all reference to the sextant and artificial horizon in the portion of the book devoted to the description of instruments." The author is

perhaps desirous that his book should not be confounded with the many treatises on nautical astronomy and the methods of reduction therein employed; but the sextant has as distinct a value in exploring new country as the chronometer, to which the author devotes a very satisfactory section. In the determination of longitude, the sextant applied to the measurement of lunar distances affords more trustworthy results than does the observation of Jupiter's satellites, on which the author would apparently rely. Occultations of stars by the moon, which is merely a particular case of the method of lunar distances, are referred to at considerable length. A numerical example of the application of the method is worked out in full, and in all the various methods of deriving the latitude and longitude detailed examples are furnished. This is a very satisfactory feature of the book, and we could have wished that the selection of examples had been more varied and had included the method of lunar distances.

If these omissions seem to us to be slight blemishes on an otherwise excellent book, it is with the greater pleasure that one can turn to the consideration of the sections which treat of matters of more novelty and

originality. In the chapter devoted to instruments we meet with a "level-quadrant" (Libellenquadrant) with which we are unfamiliar, and though it appears to be distinctly inferior to the sextant, it may be of advantage in some situations. The peculiar feature of the instrument consists in the fact that the bubble of a level carried on a rotating arm is reflected into the field of view and made to do the same service as the reflection of the sun to the horizon by means of the ordinary arrangements found in the sextant. In the case of determining the position of a balloon when the earth may be invisible owing to clouds passing beneath the observer, such an arrangement can be used with effect. In the chapter on the determination of a balloon's course, the method is applied with very considerable success. The path of a balloon from Berlin to a point beyond Breslau, a complete run of about 400 kilometres, is worked out, and the average error appears to be about 16 kilometres. This would be a large error on board ship, but the conditions are not the same, nor is there the same necessity for accuracy. The aëronaut has simply to take care that he does not run out to sea; the navigating officer has to make a land fall. calculations in this section have been materially shortened by the use of the so-called Mercator function, which, in the examples given, does away with the necessity of logarithmic tables, and suggests a method of working that seems to be well worth the little study that is necessary to master the application of it.

The

Lastly, we may mention an ingenious method of determining approximately geographical positions without the use of graduated instruments.. Threads supporting a weight at the apex of a triangle so as to ensure verticality and to give steadiness can be hung on tent poles, and over these threads the transit of stars can be observed with the naked eye. Then, knowing the time, the latitude, longitude, and azimuth can be approximately derived; and when

instruments have been injured or delayed, or are generally inaccessible, such methods are not to be despised. It would be an admirable exercise for anyone, whether he travels or not, to accustom himself to the use of such tools, and learn to what degree of accuracy he can rely on such devices.

I

THE EVOLUTION OF HUMAN SOCIETY. La Sociologie génétique. By François Cosentini. Introduction by Maxime Kovalewsky. Pp. xviii +205. (Paris: F. Alcan, 1905.) Price 3.75 francs. Na short compass this book gives an excellent bird's-eye view of a very wide territory. It begins with a discussion of the data available for the study of the evolution of human society. Even animal associations are not neglected, but, naturally, more space is devoted to the beliefs and customs of savage tribes. Our author decides wisely with regard to primitive man that much is to be learnt thus. But he deprecates rash inferences. The ancestors of civilised man, there is reason to believe, never ceased to make progress. The savages of the present day have stagnated, and may, in some cases, have retrograded. Still, when the theories that suggest themselves to the investigator of savages and their ways are modified and corrected by the study of the institutions, the beliefs, the folk-lore of civilised peoples, it is probable that the risk of serious error is reduced to very small proportions.

M. Cosentini decides in favour of a polyphyletic origin of the human race, arguing partly from the reduced fertility observable when two widely different types interbreed. After a brief but interesting account of the Palæolithic and Neolithic ages, he deals with the origin of the family. Here, as elsewhere, he shows sound judgment in his treatment of the various rival theories. He refuses to regard the patriarchal family as primitive. The more primitive the community the less sign is there of patriarchal authority. On the other hand, it would be foolish to maintain that there was ever a time in which woman was absolutely predominant. This view is precluded by the fact that primitive man had to wage incessant war against wild beasts and almost incessant war against hostile tribes. But there is abundant evidence that there was a time when a man was known as his mother's son and not as his father's, when pedigrees were traced through the female line, and when women had much more power and influence than at a later period when the patriarchal system had been developed. When the tendency changed and the paterfamilias became an autocrat within his own household, civilisation made great progress.

The family has been the nucleus which has made the higher civilisation possible, a point which, perhaps, M. Cosentini does not sufficiently recognise. Our author is, no doubt, right in holding that the idea of the family grew out of the idea of private property. The wife was the property of her husband. In very many cases he had captured her as he had captured his cattle. But with regard to monogamy, M. Cosentini does not bring out the interesting fact

that in northern climes, where it is most firmly rooted, it derives its strength mainly from the fact that one man's labour suffices for the feeding and clothing of only a small number of children. Even among animals we find the same thing. Where the work of both parents is required for the bringing up of the young, there the system of pairing is the rule. Where the young are precocious and are soon able to fend for themselves, polygany arises.

On the remainder of the book want of space forbids us to comment at length. It deals with animism, myths, language, religion, morality, law, the origin of social classes, art, industry, and The style is clear; and throughout the book M. Cosentini proves himself a fair critic and a clearheaded thinker. F. W. H.

OUR BOOK SHELF.

commerce.

Trees. By H. Marshall Ward. Vol. iii. Flowers and Inflorescences. Pp. xii+402. (Cambridge: The University Press, 1905.) Price 4s. 6d. net. THE first two volumes of the above work have been previously noticed in these columns. The present volume, which deals with flowers, is, like the others, divided into two parts. Part i. deals with the flower in general. The author has been very successful in his treatment of this vast subject; he has brought together and arranged his facts in such a clear and culty in gaining a very comprehensive knowledge simple manner that the beginner should have no difficoncerning the different kinds of inflorescences, the structure and development of flowers, as well as the meaning of their various forms and modifications. So far as possible technical terms have been carefully avoided, but at the same time it is quite impossible to treat a subject like this without using one or two terms which have a special meaning of their own which cannot be readily put into every-day language. Wherever such expressions are used their meaning is always carefully explained, and at the end of the book a useful glossary is given which will remove all mystery concerning these terms should any such

exist.

The author has naturally confined himself to a critical examination of the flowers of trees and shrubs, and the student will find here an epitome of the natural system of classification, and when this epitome has been mastered he will be in a position to understand the structure and form of the flowers of cultivated and wild herbaceous plants as well.

Part ii. is more of the nature of a flora, i.e. the author has given in tabular form a general conspectus of woody plants and their flowers, by which means any given species may be easily diagnosed at flowering time.

It is a well known fact that the willows are almost. if not, the most difficult family to deal with as regards their identification. Apart from their tendency to hybridise with each other, the willows are diœcious. which renders their identification very difficult when only one kind of flower is available. The author has special table as very ingeniously overcome this difficulty by giving a an appendix wherein the separate characters of the male and female flowers are used for the purposes of diagnosis.

This volume, like the other two, is profusely illustrated. There is also a very useful and exhaustive index at the end of the book. While vol. i., "Buds and Twigs," is a book for the winter study of trees and shrubs, we have in vol. iii. a book which is specially adapted for use in summer.

A Laboratory Guide in Elementary Bacteriology. By Dr. William Dodge Frost. Third revised edition. Pp. xiii+395. (New York: The Macmillan Company; London: Macmillan and Co., Ltd., 1903.) Price 75. net.

THIS book is, as stated in the title, a guide for practical laboratory work in elementary bacteriology. The student is taken step by step through the various processes of cleaning and setting up apparatus, Sterilisation, preparation of culture media, demonstration of gas production, and detection of certain chemical products, the result of microbial activity. The isolation and cultivation of bacteria, and staining methods, are then considered, and a few exercises are given on the physiological properties of microorganisms, such, for example, as the influence of the reaction of the medium on growth, the effects of desiccation, &c. The student is next introduced to the systematic study of types, first of non-pathogenic and then of the chief pathogenic forms. In this, as well as in the preceding portions of the book, a heading only is given, and to the exercises and practical work, and pages are left blank for the student's own notes, subheadings indicating what he should observe and look for, the facts observed being entered up by the student himself. In addition, outline diagrams are given of culture tubes which are to be filled in with the students' own drawings. In this way the guide becomes a permanent note-book and record of the student's work. Finally, directions are given for the inoculation and post-mortem examination of animals, and a key index of the characters of the more important species concludes the volume. At the end of each section a reference is given to the principal manuals and text-books of bacteriology, such as Abbott's, Chester's, Eyre's, Hewlett's, Muir and Ritchie's, Sternberg's, &c., so that the student may read up the subject. So far as we have been able to observe, the directions given are clear and concise, the exercises judiciously chosen, and the book is singularly free from errors. That a third edition should have been called for is sufficient evidence of the need for such a book, and for those who desire and work from a laboratory guide, and to lighten the labour of full and complete note taking, it may be strongly recommended. R. T. HEWLETT.

Nature-study Lessons for Primary Grades. By L. B. McMurry. Pp. xi+191. (New York: The Macmillan Co.; London: Macmillan and Co., Ltd., 1905.) Price 2s. 6d. net.

DR. C. A. MCMURRY, who has written the introduction to this volume, is one of the chief recognised authorities in America on elementary scientific education, and, indeed, on elementary education in general, and since he has probably read the proofs and given a general approval to the text, the work may be regarded as being written by one having authority. The plan of the work is to take a series of animals and plants and to show how the lessons to be learnt from them may be taught to pupils of tender years, or rather how the pupils may be trained to find out the meaning of the lessons for themselves. Having gained the confidence and attracted the interest of the pupils, the first object of the teacher should be to endeavour to foster and develop their own powers of observation and of drawing simple conclusions from such observations; and for this purpose the method adopted in the volume seems admirably adapted. Although it is not expected that all teachers will select the same objects for their texts, or that they should all follow by any means the same method of instructing, there can be no doubt of the advantage of having a list of those objects which appear most suitable for the purpose,

and also of the benefits which younger teachers may derive from a perusal of the manner in which a more experienced member of their body handles her subject. While the book appears admirably adapted for its purpose so far as teaching in America is concerned, it seems to require a word of warning when put into the hands of British teachers, and we think it would have been well had a special note to this effect been inserted in the copies intended for sale in this country. For instance, the teaching suggested in the chapter headed "The Robin" will apply for the most part excellently well to the bird so designated in this country; but when the inexperienced teacher (who is unaware that the so-called American robin is not our own familiar red-breast) reads that robins lay blue eggs he, or she, will be apt to put the book aside with the remark that the author does not know her subject. Again, it would much have simplified matters had the English teacher been informed that the plants known in America as Morning-Glory" include the one commonly called Convolvulus major in country.

[ocr errors]

this

With these limitations (which refer only to its issue in this country), we have nothing but praise to bestow upon Dr. and Mrs. McMurry's efforts to establish elementary biological teaching upon a sensible and practical basis. R. L.

Einführung in die Vektoranalysis mit Anwendungen auf die mathematische Physik. By Dr. Richard Gans. Pp. ix +226. (Leipzig: Teubner, 1905.)

66

Price 8 marks.

THIS well-written book gives the usual definitions of scalar and vector products, introduces the now familiar differential operators "div" and "rot " (or curl "), and uses them skilfully in the simpler applications of the line, surface, and volume integrals, associated with the names of Green, Gauss, and Stokes. The necessity for vector analysis in electromagnetic work is becoming more generally recog

nised, and Dr. Gans deserves the thanks of all for his able presentation of the outlines of the method, which, nevertheless, is at its best a "Quaternionenstenographie," as C. Neumann felicitously nicknames it. One has only to compare the demonstrations here given, which are primarily Cartesian and are then transformed into the concise vector notation,

with corresponding quaternion demonstrations, such as may be found in Joly's Manual," to see plainly the analytical gulf which separates Hamilton's calculus from other vector analyses, which are essentially shorthand notations. The mathematical historian of the future will find much food for thought in the mental shortsightedness of many vector analysts who delight in the use of contraction symbols like grad, rot, div, but despise the Hamiltonian selective symbols V and S, which with the real ▾ give the whole theory in exquisite compactness and flexibility. On a folding sheet at the end Dr. Gans gives a table of eighteen transformation formula, which presumably must all be learned off by rote. There does not seem to be any resemblance among the formulæ (h), (o), (q), which give respectively the equivalents of [ABC, rot rot A, rot [AB]. In the quaternion notation VAVBC, VVVVA, VVVAB, they are seen to be of the same “form,” and are, indeed, analytically amenable to the same treatment. This is but one illustration of the inferiority of the Quaternionenstenographie" to the real quaternion analysis. Dr. Gans gives interesting applications in hydrodynamics and in Maxwell's electromagnetic theory, but is limited somewhat by the fact that in this introduction there is no account taken of the linear vector function or matrix.

66

LETTERS TO THE EDITOR.

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

OUR eclipse took place in the midst of the fierce heat of the Gibleh, or Sahara sirocco; but an hour or two before totality the wind very fortunately changed, and brought skies of the highest possible optical transparency. There was no wind, and the conditions, except for the intense heat, which we momentarily feared would snap our great cameras, were the most nearly perfect imaginable at a sea-level station.

Unfortunately, on account of leaving home at very short notice, we brought no spectroscopic outfit, and our efforts were directed solely toward coronal photography with automatic and semi-automatic coronagraphs, and to exposure of plates for the slightly suspected intra-Mercurial planet. Other branches of our work related to coronal sketches, both with and without occulting discs, and to shadow band observations, both optically and photographically.

By the kindness of His Majesty's Government, represented by Mr. Alfred Dickson, Vice-Consul, the American expedition from Amherst College was permitted to establish its instruments on the terrace of the consulate, in the midst of the white city-in precisely the same spot occupied for the similar eclipse of 1900.

Many citizens of Tripoli took immediate and constant interest in our operations, and contributed very greatly to

our success by their liberality in granting that service which only the chief of an expedition remote from home can fully appreciate. I am glad to mention especially Mr. W. F. Riley, Mr. W. H. Venables, Maris de Nunes Vais, the excellent photographer of the expedition, and Etim Bey, a Turkish gentleman resident in Tripoli, whose unique collection of photographic and mechanical appliances was frequently and helpfully drawn upon. The observations of shadow bands were conducted by parties organised by Mrs. Todd and Miss Todd, and will be reported to my friend Mr. Lawrence Rotch, of Blue Hill, at whose request they were made. These bands were seen as early as ten minutes before totality, and had many remarkable and pronounced peculiarities. They were wavering and narrow, moving swifter than one could walk, at right angles to the wind, their length with it, and waxing and waning five times during the eight minutes preceding totality.

FIG. 1.-Total Solar Eclipse of Photographed at August 30.

Tripoli.

The coronal sketches revealed nothing out of the ordinary. Extended rays beyond the occulting discs were looked for eagerly, but the disc (8 inches diameter at 35 feet distance) covered everything. The sky and general illumination were exceptionally bright. Totality as predicted was 3m. 9s. in duration; as observed 3m. 6s.

Our chief and largest instrument was a photographically corrected lens by Clacey, of 12 inches full aperture. To this was attached an orthochromatic screen for photographing Baily's beads, and a Burckhalter occulter as described by the writer four years ago in the Monthly Notices. Of the results obtained with this instrument I shall write elsewhere; about twenty exposures were made with it, and the beads are excellently shown in the accompanying photograph. The occulter was only in part successful.

Alongside it were the large Clark cameras, containing a pair of 3-inch lenses of 11 feet inches focus, which took plates on which are a great number of stars, not

yet fully examined. Owing to the unexpected brilliancy of the sky, the plates were exposed longer than would seem to have been wise. Everything to the eighth magnitude seems to have been caught, however.

A third instrument was a 3-inch Goerz doublet of about 18 inches focus, from which I removed the back lens, increasing the focal length to 33 inches. This was attached to one of the automatic movements used in my previous expeditions of 1896, 1900, and 1901. It was geared up to a rate of 265 photographs during the 189 seconds of totality, the exposure being about second for each. Most of these pictures are very good, and I enclose a print from one of them (Fig. 1), which does not however, do the original negative justice. The corona was much less impressive, it strikes me, than other coronas I have seen 1878 and 1900 in clear skies, and 1887. 1889 (b), 1896, and 1901 in clouds; in fact, the shadow bands and Baily's beads seem to have been rather more interesting to the general observer than the corona itself. British Consulate, Tripoli, Barbary, August 31.

DAVID TODD.

On the Class of Cubic Surfaces.

IN Salmon's Geometry of Three Dimensions," the classes of the twenty-three different species of cubic surfaces are stated; but the process by which these results are obtained is not obvious. I therefore propose to indicate an easy method.

The class of a plane curve is equal to the number of tangents which can be drawn from a point not on the curve; hence the class of a curve is equal to the degree of its reciprocal polar. And since the line joining two points on a surface corresponds to the line of intersection of two tangent planes to the reciprocal surface, it is necessary, in order to make the theories of curves and surfaces correspond, to define the class m of a surface to be equal to the number of tangent planes which can be drawn through a given straight line. Let (a, B. v. 8) be quadriplanar coordinates referred to a tetrahedron of reference ABCD; then the equation of the tangent plane at any point (f, g, h, k) is dF dF + B + adf ag

[graphic]

dF dF Ydh

+ 8 <=0 ak

(I)

and if this plane passes through the line CD, we must have dF/dh=o, dF/dk= =0. Hence the points of contact of the tangent planes which pass through CD are the points of intersection of the three surfaces

[blocks in formation]

and their number is equal to n(n-1)2, which is the value of m for an anautotomic surface. The elimination of (a, B) between (2) will furnish a binary quantic in (7, 8) the degree of which is equal to the class of the surface.

It is obvious from geometrical considerations that a conic node must diminish the class by 2. The equation of a cubic having a binode B, is ayd+u, =0, where u, is a ternary cubic in (B, 7, 8). Differentiating with respect to y and 8, and then putting 8-Ay, we obtain

λαγ+3=0

λay + du'g/dy=0 ay+du's/d8=0

(3)

where the accents denote what the quantities become when 8 is put equal to Ay after differentiation. Equations 131 are those of the sections of the cubic and the polar quadrics of C and D by any plane through AB; and since they intersect in three coincident points at A, m=12-3=9. The equation of a cubic having a binode B, at A is αγδ + β + β2 + vg=0

(4) where visa binary quantic in (7,8). Let vndvn/dy, v=dv__. Differentiating (4) with respect to 7 and 8, and eliminating we obtain

α,

[blocks in formation]
« AnteriorContinuar »