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Prize Competition

EGYPTIAN GOVERNMENT

SCHOOLS. In view of the extension of Secondary Education in Egypt, applications are invited for new ASSISTANT-MASTERSHIPS in Secondary Schools under Ministry of Public Instruction. Masters to begin work in September, in Cairo or Alexandria, and to teach in English exclusively. Over 400 boys in each school, mainly Mohammedans. In the case of one of the Masters now required, the subject mainly essential is Science (F. xperimental Physics and Chemistry); six of the new Masters will be principally engaged in teaching Mathematics (Arithmetic, Geometry, and Algebra); the others will be concerned more particularly with the teaching of English. Candidates must be not less than 23 por over 30 years of age, have a robust constitution, and have taken a University Degree in Honours. They must have ex. perience as Teachers : preference will be given to applicants who hold a Diploma in Teaching, Salary, 4295 per annum (EEg.24 per mensem), rising to £393 per annum (CF9.32 per mensem). Allowance for passage out to Egypt. Teaching hours, on an average, rour daily, Fridays only excepted. Summer vacation not less than two months.

Applications, with full statement of qualifications, and accompanied by copies only of testimonials, must be sent in before May 15, 1905, marked outside “Assistant Masterships," and addressed to the Secretary: GENERAL, Ministry of Public Instruction, Cairo, Egypt, to whom candidates may apply for further information.

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TO SCIENCE AND MATHEMATICAL

MASTERS.-Required (1) Physics Master for Secondary School. $. 150, non-res. (2) Mathematical Master for Public School, Sea-side. 1.150. (3) Science and Maths. 6.100, resident. Army Coaching Establi.bment. (4) Mathematics and English, Wanted in September. £100, resident. Grammar School. - For particulars of above and other Science and Matbl. posts, address Griffiths, SMITH, POWELL & SMITH, Tutorial Agents (Estd. 1833), 34 Bedford Street, Strand, London.

PYRO-METOL DEVELOPER

Competition closes May 15, 1905

Entry forms and full particulars from

all chemists, or from

WARRINGTON MUNICIPAL MUSEUM.

APPOINTMENT OF ASSISTANT CURATOR. The Committee invites applications from persons having a knowledge of Zoology and Botany, and some experience of Museum work.

Salary, £80, rising £10 yearly to £120. Particulars may be had from the undersigned, to whom applications, stating qualifications and experience, with reference and copies of recent testimonials, are to be sent not later than May 3.

CHARLES MADELEY, Curator.

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FOR SALE.-X-Rays Outfit. 10" Apps Coil,

" , 6. “Q21" accumulators, stand, iubes, sundries, in good working order. Also 6" Apps Coil and 6" Harvey and Peak Coil. Can be seen by appointment, London Stereoscopic Company, 54 Cheapside.

ARMBRECHT'S

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ASTRONOMICAL TELESCOPE (by Sir

Howard Grubb), equatorial, very fine og.. 6-in. clear, driving clock,
silver circles, position circle, &c. Must be sold.- Full particulars,

Downes, 41 Lorne Street, Leith.
TYPE-WRITING UNDERTAKEN

HIGHLY EDUCATED WOMEN ACCUSTOMED TO SCIEN
TIFIC MSS. (Classical Tripos, Intermediate Arts, Cambridge Higher
Local: thorough acquaintance with Modern Languages). Research,
Revision, Translation. Scale of charges on application. The Cam.
bridge Type-writing Agency, 10 Duke Street, Adelphi, W.C.

Specialities.

Radium Brom, in 5 mg. Tubes

for CANCER CURE, Calcium Metal, 16 per oz.

(minimum Lithium Metal (Chem. pure) 1 gram. tubes. Rubidium

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17 REISONABLE PRICES. Apply for Special List of Rare

Elements, Post Free.

66

Beryllium
Strontium,
Tellurium
Uranium

m mn Above and the rest of the Rare Elements can

be immediately supplied from stock.

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SECOND-HAND TELESCOPES. in. Dallmeyer Equatorial, Clock, complete, £100.4} in. Alvan Clark, Equatorial by Cooke, £50. Several 3 in. Student Telescopes, by

leading makers, £4 10s., £6 10s., £8 10s., £10. SECOND-HAND SPECTROSCOPES, Single, 2, and 3 Prism, by Browning, £4 10s., £8 10s., £10.

SECOND-HAND MICROSCOPES. Watson's Edinburgh H.. powers and fittings, complete, as new, £16 10s. Swift Army Bicienia, complete, £15. Leitz zb, with rack,

substage, and fittings, £6 10s. MANY OTHERS, ALL KINDS. LISTS ON APPLICATION.

A. CLARKSON & CO., 28 BARTLETT'S BUILDINGS, HOLBORN CIRCUS, LONDON.

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(Late MOTTERSHEAD & CO.),

FREDK. JACKSON & Co. E. GEORGE & SONS, BOOKSELLERS
14 CROSS STREET, MANCHESTER
LABORATORY FURNISHERS,

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Goods Entrance : 10 Half-Moon Street.

Apparatus for estimation of sulphur in spent oxide.

and Dealers in Scientific, Literary, and other Journals and Reviews, and Publications of Learnec and scientific Societies, in complete Sets, Volumes.

or Parts.
Agents for British, Foreign, and Colonial Libraries, Institutions, 37
Private Book Buyers. Current Catalogue sent post free on app'ıcatre
Broks sought for. Correspondence Invited. All communications ans
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All Orders promptly executed. Established 1820.
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CHEMICAL AND PHYSICAL

APPARATUS
of every Description.
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DAVID NUTT, 57-59 Long Acre, London, W.C.

Importer of Foreign Literature and Publisher. All FOREIGN WORKS reviewed in Nature are on sale or can be procured at shortest notice from David Nurt, at Continental Prics.

SUBSCRIPTIONS can be effected through DAVID NUTT to all FOREIGN PERIODICALS.

RARE and OUT OF PRINT FOREIGN WORKS sought for witbout charge, and supplied at the most moderate prices. SECONDHAND FOREIGN CATALOGUES supplied regularly on demand, and orders executed therefrom.

GLASS BLOWING.

All kinds of Experimental Glass Blowing promptly and correctly carried out for Scientific Men, Laboratories,

&c., from rough Drawings, or repaired. Inventors' Ideas Worked out as per Instructions. A. C. COSSOR, 54 Farringdon Road, London, E.C.

(CONTRACTOR TO H.M. GOVERNMENT.)

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SCIENTIFIC WORTHIES.

A List of this series of Steel and
Photogravure Portraits of Men of
Science will be sent post free to any
reader of “Nature" on application to

the Publishers.
ST. MARTIN'S STREET, LONDON W.C.

THE IRISH NATURALIST.
A Monthly Magazine of Irish Zoology, Botany, and

Geology. Price 6a.
Edited by GEO. H. CARPENTER, B.Sc., and R. LLOYD

PRAEGER, B.A.
Annual Subscription, 5s. Post Free to any Address.
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(to which Address Subscriptions should be sent).
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RECENT & COMING ECLIPSES.

BY Sir NORMAN LOCKYER, K.C.B., F.R.S. Second Edition, containing an account of the Observations made at Viziadrug, in India, in 1898, and of the conditions of the Eclipses visible in 1900, 1901 and 1905.

8vo. 6s. net. MACMILLAN AND CO., LIMITED, LONDON.

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TO SCIENTIFIC MEN ABROAD

RICHARD J. COWEN, L.R.C.S.I., L.R.C.P.I., &c. THE TESTING OF CHEMICAL

REAGENTS FOR PURITY. London : H. J. GLAISHER, 57 Wigmore Street, W.

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Authorised translation of the Third German Edition by

J. A. WILLIAMSON, F.C.S., and L. W. DUPRÉ. English Books (New and Second-hand) and Periodicals AN INVALUABLE LABORATORY COMPANION. A promptly supplied at lowest rates. German and French concise and comprehensive summary of Analytical Methods as Banknotes and Stamps received in payment. References applied to Chemical Reagent:. 400 Reagents are dealt with. in all parts of the world.

Every lact and factor of value is given in full. W. MULLER, Export Bookseller, London, W.

Price 12/6 net. Postage 5d. extra, Abroad rod. extra. 59 CASTLE STREET EAST, OXFORD STREET.

RUBBER, GUTTA PERCHA

AND BALATA.

By FRANZ CLOUTH (Cologne).
A Road-Book to the Stars.

Contains 3 Maps and Chart on the Rubber producing Districts,
By T. E. HEATH.

and Price Fluctuations of PARA RUBBER since 1861. Distances and Luminosities by a Simple Scale. Stereo- Royal 8vo. 242 pp. text. Prices, 12/6 net, postage 5d. ; grams show Sun and Stars of known Parallax hanging in space of three dimensions.

Colonies 13/6, and other countries 15/-, post free. Price 5s. net. KING, SELL, & OLDING, LTD., 27 Chancery Lane, London. MACLAREN & SONS, 37 & 38 Shoe Lane, London, E.C.

OUR STELLAR UNIVERSE,

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SCIENTIFIC AND

EDUCATIONAL BOOKS

ELEMENTARY

MICROSCOPY. By F. SHILLINGTON SCALES, F.R.M.S.

Pp. xii + 170 with 78 llustrations. Price 3s, net.
"A more pracıical handbook on the microscope does not exist."-
Pharmaceutical Journal

BAILLIÈRE, TINDALL AND COX,
8 HENRIETTA STREET, COVENT GARDEN, LONDON.

With 30 Original Illustrations. Price 28. 6d.
The HYGIENE of the MOUTH.
A Guide to the Prevention and Control of Dental Diseases.
Rv R. DENISON PEDLEY, L.D.S. Eng., F.R.C.S. Ed.,
Dental Surgeon to the Evelina Hospital, Southwark.

BY THE SAMR AUTHOR,
The DISEASES OF CHILDREN'S TEETH

Well Illustrated. Price 75. 60.
SEGG & CO.. ako and 2oRegent Street, Londor, w.

NEW & SECOND HAND.
LARGEST STOCK in LONDON of SECOND-
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TARY and ADVANCED SCIENTIFIC BOOKS

at about HALF PUBLISHED PRICE. Mathematical, Theological, and Foreign Books.

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Now Ready, and sent post free on application. H. J. GLAISHER, Remainder and Discount Bookseller, In addition to Medicine and the allied Sciences, the Library 57 Wigmore Street, London, W.

includes the subjects of Physics, Chemistry, Electricity,

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London: H. K. LEWIS, 136 GOWER STREET, W.C. LONDON : A. SIEGLE, 2 LANGHAM PLACE, W. Telegrams: “PUBLICAVIT, LONDON." Telephone : 10,721 CENTRAL.

THE NEW "STUDENT'S" STANDARD BAROMETER.

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In a glass vessel containing water a broad strip of manganin is immersed. The strip can be made to carry an electric current, and is so wound that it can be used as a stirrer, a very efficient circulation resulting. The resistance of the manganin strip, having a low temperature coefficient, can

ascertained very exactly, so that the energy dissipated is known in terms of the current. A thermometer immersed in the water shows the rise of temperature produced. (See Ayrton's “ Practical Electricity,” 1900 Edition, page 320.)

2

(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 far Demonstration purposes.

The construction is on that of the well-known" Fortis 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 attachment 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 "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 milli metres), and with thermometer on other scale, at sare price.

I NATURE says :-"Provides an accurate instrement at a moderate cost."

FULL SIZE STANDARD BAROMETER of same design, bore oʻs" diameter, inches and millimetre scales, verniers reading to o'coz inch and o'r m/m, og 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 METEOROLOCICAL INSTRUMENTS

Contractors to H.M. Government. Estd. 1750 Telegrams," Rapkin, London." Telephone, 1981 Holbora

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Price complete, with thermometer divided in tenths of a degree from 0° to 50° Centigrade,

£2 15 0.

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REYNOLDS & BRANSON, LTD. W.H.SMITH & SON'S

LIBRARY

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oFFAE: 186 STRAND, LONDON, W.C.

а

We say

THURSDAY, APRIL 27, 1905.

set of covariants of the quintic. A short chapter on simultaneous systems brings us to Hilbert's theorem,

with which the algebra of binary forms may be said THREE CAMBRIDGE MATHEMATICAL

to end. Chapters x. and xi. deal with geometrical WORKS.

interpretations, and in particular with apolarity. The

sections dealing with ternary forms are less complete, The Algebra of Invariants. By J. H. Grace, M.A.,

as the authors have considered that “ with the methods and A. Young, M.A. Pp. vii + 384. (Cambridge:

known up to the present the treatment of ternary forms The University Press, 1903.) Price 1os. net.

is too tedious for a text-book." The Dynamical Theory of Gases. By J. H. Jeans,

Mr. Grace has previously been associated with the M.A. Pp. xvi +352. (Cambridge: The University

production of several mathematical text-books of a Press.) Price 155. net.

quite elementary character, and the present book bears A Treatise on the Analytical Dynamics of Particles and

many unmistakable traces of his experience as Rigid Bodies. By E. T. Whittaker, M.A. Pp.

writer in making a somewhat difficult subject appear xiii +414. (Cambridge: The University Press,

relatively easy. 1904.) Price 125. 6d. net.

“ somewhat” difficult, because the subject WHATEVER opinions may be felt as to the of Mr. Jeans's new book is incomparably harder than

desirability of University Presses competing the " Algebra of Invariants." This difficulty arises with private firms in swelling the already too large largely from the fact that the kinetic theory of gases flood of school geometries or issuing cram books is closely associated with the representation of physical for compulsory Greek examinations, there can only be

phenomena as they actually exist, and with all the one opinion as to the series of standard treatises on

difficulties connected with irreversibility and the existhigher mathematics emanating at the present time ence of temperature. It is only by statistical methods from Cambridge. In a country which, in its lack

that these phenomena are amenable to the equations of national interest in higher scientific research, par- of reversible dynamics, and with every method of ticularly mathematical research, stands far behind attack some assumption must be made, since if any most other important civilised countries, it necessarily motion of a molecular system exists it is equally devolves on a University Press to publish advanced conceivable that the opposite motion should exist. mathematical works. We may take it as certain that Even Willard Gibbs's appeal to experience quoted the present volumes will be keenly read in Germany on p. 167 does not get over the difficulty. If we put and America, and will be taken as proofs that England red and blue ink together into a vessel and stir them contains good mathematicians, though Englishmen up, it is true that if the inks differ in nothing more as a nation may be unaware of their existence, with the than colour the result is a uniform violet ink. But exception of the senior wrangler of one year, who is this is because the inks are viscous liquids the forgotten the next.

motions of which are irreversible. If they were perfect For years Salmon's “ Higher Algebra ” has been the liquids perfect mixing would not take place, and the treatise which has done most to interest English effect of stirring would merely be to produce vortex students in invariants. At the present time a good motions in which the vortex lines always contained deal more is wanted in order to bring our knowledge the same particles and remained constant in strength. up to date. Messrs. Grace and Young have en- If we mix counters in a bag, the motions of the deavoured to meet present requirements in a well counters are retarded by friction; if the counters defined direction. As they state in their preface, the correctly represented perfectly reversible systems they book

would never come to rest. was started as an attempt to meet the need expressed

Mr. Jeans in his preface considers that the disby Elliott in the pteface to · The Algebra of Quantics' crepancy between theory and experiment in connection

- a whole book which shall present to the English with the ratio of the specific heats of a gas “is of reader in his own language a worthy exposition of greater importance than all the others together," and the method of the great German masters remains a he has endeavoured to emphasise the fact that when desideratum.'

account is taken of the interaction between matter While no book, unless it were written in four and the ether, theory and experiment harmonise : languages, could satisfy the patriotic aspirations of well as could be desired. But as soon as this ether every native of our country by appealing to him “in is taken into account we have a simple means of his own language," the production of an English obviating the irreversibility difficulty by saddling the book on a subject largely developed in Germany meets ether with the whole responsibility. So long as a distinct want.

physicists are contented, in solving the differential The subject is practically started ab initio. The equations of wave motion in a medium, to omit the treatment does not strike us as very hard to follow, terms which represent waves converging from an although it is difficult for a beginner at first to infinite distance towards a centre of disturbance, so master 'the symbolical notation, especially in the long will there be an easy way out of the puzzling definition of transvectants (chapter ii.). In chapter contradictions arising out of Boltzmann's H-theorem. vi. the authors introduce Gordan's theorem, according But there is really no reason why the presence of to which the number of covariants of a binary form is a molecule in an indefinitely extended ether which always finite, and in the next chapter they employ his lindoubtedly possesses some energy should not bring method of proof to obtain the complete irreducible Labout the convergence of waves coming in from an

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