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Scientific Apparatus Makers, NEWCASTLE - UPON - TYNE. Makers and Dealers in all kinds of Chemical and Physical Apparatus for Schools and Colleges, Works' Laboratories

and Special Research Work. CONSTRUCTION OF NEW FORMS OF APPARATUS

SANCER-SHEPHERD & CO.,

5, 6 & 7, Gray's Inn Passage, Red Lion St., Holborn, London, w.C.

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ROYAL INSTITUTION OF
OF The UNIVERSITIES of MANCHESTER,

,

LIVERPOOL and LEEDS.
GREAT BRITAIN.

The next MATRICULATION EXAMINATION will commence on

Wednesday, July 5, 1905. and will be held simultaneously at the three ALBEMARLE STREET, PICCADILLY, W. Universities and in Schools approved by the Joint Matriculation Board. TUESDAY next, March 21, at Five o'clock, Professor W. E. DALBY,

The fee is due on or before June 3. M.A., B.Sc., M.Inst.C.E. First of two lectures on “Engineering

Information as to Scholarships awarded on the results of this examination Problems." Half-a-Guinea the Course.

and on other matters may be obtained from the undersigned. THURSDAY, March 23, at Five o'clock, Thomas G. JACKSON, Esq.,

R. F. GWYTHER, R.A., M.A., F.S.A. First of two lectures on "The Reasonableness of

Secretary to the Joint Matriculation Board, Architecture.” Half-a-Guinea.

Owens College, Manchester. Subscription to all Courses in the Season, Two Guineas.

FOR SALE.-The Instruments in the DEPARTMENT OF TECHNOLOGY.

Observatory of the late Mr. Edward Crossley : a g-in. and a 4f-in CITY AND GUILDS OF LONDON (both photo-visual object glasses) Equatorial Refractor by Cooke;

3-in. Transit Circle by Cooke ; a 6-in. Sextant and a s-in. Transit INSTITUTE.

Theodolite by Troughton and Simms; Siderial Clock by Cooke;

Parallel-wire and Double-image Micrometers by Troughton and EXAMINATIONS in TECHNOLOGY will be held from April 29 till Simms; Microscopes by Ross and Zeiss; Apparatus for Lectures on June 24.

Light, Polarisation, &c., by Harvey and Peak; Measuring Bars and All applications from Local Secretaries for Examinations

in Technology Rods-12.in., 40-in., 3-ft., 10-ft.-by Troughton and Simms; Standard must reach the offices of the department on or before MARCH 20.

Barometer by Hicks; Two Spectroscopes; Two Controlled Clocks Only by payment of an additional fee can applications be received after

Apply to Mr. J. GLEDHILL, Bermerside, Halifax. that date. Candidates in Technology not attending any registered class should apply. Hepaticæ Britannicæ Exsiccatæ, being a

Local It is only in very exceptional cases, when no other arrangements can be Collection of 100 Specimens of British Hepaticæ, including many rare made, that applications will be entertained for the examination of candi. species, carefully prepared, named and mounted. Pric i 35.-W. H. dates at the Offices of the Department. All such applications should be PEARSON, Park Crescent, Victoria Park, Manchester. addressed to the DEPARTMENT OF TECHNOLOGY, CITY AND GUILDS OF LONDON INSTITUTE, EXHIBITION ROAD, LONDON, S.W., and should be accompanied by a Postal Order for is. 6d.

For Sale.—Extensive Collections of British in addition to the amount of the fee, as given in the programme, the subject

Lepidoptera, Coleoptera, Tropical Butterflies, Cabinets, &c. Carrectly and grade of the Examination being clearly stated.

named type collections at very moderate prices. - Particulars from

A. FORD, Hillside, Sunnyhill, Pokesdown, Bournemouth.
TO SCIENCE, MATHEMATICAL AND
OTHER MASTERS.-Required (1) Second Master for important

TYPE-WRITING UNDERTAKEN BY Grammar School-Mathcs. and Science. Salary, £160 to £180. HIGHLY EDUCATED WO`IEN ACCUSTOMED TO SCIEN. (2) Head Master for Public Institution School near London. Know- TIFIC MSS. (Classical Tripos, Intermediate Arts, Cambridge Higber ledge of Commercial Education necessary. Age 35 to 45, unmarried. Local, thorough acquaintance with Modern Languages). Research, Salary, £200, with board and private rooms. (3) Chemistry, Botany Revision, Translation. Scale of charges on application. The Camand some Physics, £150 to £160. (4) Chemistry, Mathcs. and Botany, bridge Type-writing Agency, to Duke Street, Adelphi, W.C. £140. Particulars of the above and other Science posts will be sent on application. Candidates seeking appointments either at once or SECOND-HAND MICROSCOPES. for after Easter are invited to apply forthwith. Address, Griffiths,

(Monocular and Binocular.) Smith, Powell and Smith, Tutorial Agents (Estab. 1833), 34 Bedford Street, Strand, London.

By Swift, Watson, Beck, Crouch, Collins, Zeiss, Leitz, &c

SECOND-HAND TELESCOPES.
B.A. AND
B.Sc. EXAMS.

(Refractor and Reflector.) VARIOUS SIZES.

By Cooke, Grubb, Alvan Clark, Wray, Calver, Browning, MATRICULATION, INTERMEDIATE, FINAL.

Steward, Newton, Watsori, Dollond, Negretti, Banks, PREPARATION by CORRESPONDENCE and ORAL TUITION

Fraunhoffer, &c. a THOROUGHLY INDIVIDUAL SYSTEM. Fees based on

LISTS ON APPLICATION,

A. CLARKSON CO., The STAFF includes Graduates of Oxford, Cambridge, London, and Royal Universities, Science Medallists, Prizemen, Scholars, &c.

28 BARTLETT'S BUILDINGS, HOLBORN CIRCUS, LONDON, E.C. SINGLE SUBJECTS TAKEN: Science, Mathematics, Logic, Psychology, Political Economy, Latin, Greek, French, German, &c.

For terms, &c., address Mr. J. CHARLESTON, B.A. (Lond. and Oxon.), Burlington Correspondence College, Clapham Common, London, S.W.

Best Make and Finish. BOTANY TUTOR. Stipend, £300.

SET SQUARES,
WELL KNOWN COLLEGE.

T SQUARES,

DRAWING BOARDS. SCIENCE & MATHEMATICAL TUTORS. A List of Easter Vacancies sent.

Obtained through any Optician. ORELLANA

CO., ROBERT NICHOLL, 153 HIGH HOLBORN, LONDON. 80 Wigmore Street, Cavendish Square, London, w. (lale 44 Old Bond Street).

FOR SALE, at Reduced Prices. MATHS. and SCIENCE. Attractive Appt.

MICROSCOPIC SLIDES (dispersal of Mr. Hornell's collection), se Experienced and successful Army Tutor desires to meet with a Univ.

Micro. Editor's note, June No. of Knowledge, Sections of Flower Boda man with above quals., able to take responsibility of Vice-Principal, &c., also Marine, suitable for Students and Exhibition, prices from with view to, later, sharing profits, and a possible partnership: . Age 3d. each. 26–32. Salary, £150, res., or £200, non-res. Many other Science MICROSCOPE, Baker's D.P.H. and fittings, £7 165. ; Beck's London Appts. Write or call

, NeeDES & Sellicks, Clock House, Arundel and fittings, £6 6s. ; many others, Pillisher, Ross, &c. Objectives Bull Street, Strand, W.C.

Eye Condensers. Abbe Condensers. Goerz PRISMATIC BINOCULARS

Photographic Lenses. SURGEON'S OPERATION Outfir, very fire, MERCHANT VENTURERS'

new, for sale, cheap. LANTERN SLIDES, English Church Arcir TECHNICAL COLLEGE, BRISTOL.

tecture. Many other useful articles. Lists.

Mr. HERBERT CLARKE, 104 LEADENHALL STREET, LONDON. JUNIOR ASSISTANT for PHYSICS ; £130 to £160. Particulars obtainable from the REGISTRAR by sending a stamped addressed foolscap THE " SIRIUS" FOCUS TUBE. envelope, not later than March 23, 1905.

Sole Maker, CHEMIST, B.Sc. (1st Class Honours in

H. HELM, Chemistry), Ph.D., F.I.C., late 1851 Exhibition Science Scholar, with large experience in Chemical research and in quick and accurate

66 Hatton Cardes, methods of analysis, including all classes of minerals, gas analysis, foods and commercial products, desires permanent and responsible position in

London. Works or Laboratory (as partner or chief assistant), or where experience

Glass Blower would be useful; Great Britain or abroad, climate and distance no

ACTUAL MAKER object. Has held several important appointments, and understands the handling of workmen. Energetic, and peaks German ard Spanish. Excellent testimonials. Salary required, £100 to £150 to commence

IX-Ray and awar with. Please address "B. M.,"c/o NATURE.

Tales, &

on success.

. .. DRAWING INSTRUMENTS.

ALSO

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RADIUM "CLOCKS."

CALCIUM
METAL

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:

Having made a special study of these instru-
ments, we are in a position to supply :

1. FOR THE ..
LECTURE TABLE ,

(AS ILLUSTRATED).
2. FOR LANTERN .

SLIDE USE . .

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Discharging every 40 to 100
seconds accoriling to quantity

of Radium.
PRICES will be quoted by

return post.
Kindly Note.- We cannot send
these clocks by parcel post 1201

lend them on hire.

99.3 to 99.6 per cent.

made by Electrolysis from Calcium Chloride.

We make a special feature of CHEMICALS and APPARATUS of all kinds.

PRICE LIST FREE.

Heretofore sold at

£9 the ounce. We now offer same at

1/6

RADIUM ON HIRE. TERMS ON APPLICATION.
W. MARTINDALE,

MANUFACTURING CHEMIST,
10 NEW CAVENDISH ST., LONDON, W.

Telephone: 1797, PADDINGTON.
Telegrams: MARTINDALE, CHEMIST, LONDON.

(One Shilling and Sixpence)

THE OUNCE.

oz. weight, 24 Shillings, post paid.

16 Facsimile of a bar

In Bars of 4, 8, 16 ounces,

or Tins containing 4 pounds 4 ounces.

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In quantities of 28, 56, 112 pounds, Considerable Reduction.

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ARMBRECHT,
NELSON & CO.,

71 & 73 Duke St.,

Grosvenor Square,

LONDON, W, Telephone-Gerrard 4942

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Just arrived, fresh

supply of

CARBORUNDUM

Price of Apparatus, with Accumulator £10 10 0

Connector & Handle for Electrodes 0 17 6 Electrodes, various patterns, each

0 7 6 Our ordinary Electrodes, with plug attachment, fit this handle.

Descriptive Leaflet post free. ILLUSTRATED CATALOGUE in X-RAYS, &c. (including

INSTRUCTIONS TO BEGINNERS), post free. HARRY W.

COX, Ltd., FACTORY AND OFFICES 1a ROSEBERY AVENUE, & 15-21 LAYSTALL ST., LONDON, E.C.

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PASTORELLI & RAPKIN,

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AND

215. Det

The effective vertical range is one metre, the scale being divided in millimetres with vernier reading to 05 mm.

The telescope has object glass of 25 mm. aperture, rack and pinion focussing and sensitive spirit level.

Range of working distances, trom 60 cm. to infinity.

(Established 1750),

LTD Contractors to H.M. Government, 46, HATTON GARDEN, LONDON, E.C.

Telephone No. 1981, Holborn. Telegrams—“Rapkin, London." ACTUAL (WHOLESALE) MAKERS OF ALL KINDS OF METEOROLOCICAL INSTRUMENTS.

Quarto (11 X 8), cloth. 245. net.

A MONOGRAPH OF
THE ANOPHELES MOSQUITOES

OF INDIA.
By Capt. S. P. JAMES, M.B. (Lond.), and

Capt. W. GLEN LISTON, I.M.S.
With 15 Full-page Coloured Plates, 64 Mustrations in Half-Tone (ce 15
Plates), a Map, and 30 Diagrams and Illustrations in the Tear
Second Edition. Demy 8vo, cloth. 75. 6d. net.

MALARIAL FEVER
MALARIAL PARASITES

IN INDIA.
By Major ANDREW BUCHANAN, I.M.S., M.D.

Profusely Illustrated with Coloured Plates and Charts
Fourth Edition. Super Royal 8vo, cloth. 337 PP.
GAME, SHORE, AND WATER

BIRDS OF INDIA.
With Additional References to their Allied Species in other parts of te

World.
By Col. A. LE MESSURIER, C.I.E., F.z.s., F.G.S.

With 180 natural size Illustrations.

Crown 8vo, paper cover. 28. 6d. net THE BIRDS OF CALCUTTA. A Series of Short Humorous but Faithful Descriptions of the Cresson

Birds of Calcutta.
By FRANK FINN, F.Z.S., M.B.O.U. (late Deputy Superintendeel

Calcutta Museum)
With Illustrations by H. GOODCHI D.

Demy svo, cloth. 300 pp. 55. bet. ASTRONOMY WITHOUT A

TELESCOPE.

By E. WALTER MAUNDER, F.R.A.S. An Introduction to the Knowledge of the Constellations, and to tbe liar of the Heavens with the unassisted Sight. Fully Illustrated with the Plates, and with Maps and Charts, also twelve Star Maps forming a

COMPLETE CELESTIAL ATLAS W. THACKER & CO., 2 CREED LANE, EC.

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waves

same

THURSDAY, MARCH 16, 1905.

the preface, the author deals with the properties of vibrating mechanical systems, e.g., the air in a

closed space, or a stretched string. After some disMODERN OPTICAL THEORY.

cussion as to periodic motion in general, the equation An Introduction to the Theory of Optics. By Prof. of motion for an elastic body, propagating plane A. Schuster, F.R.S. Pp. XV + 340.

(London :

of distortion, is found in an elementary Edward Arnold, 1904.) Price 155. net.

manner, and certain fundamental results are shown PROF. SCHUSTER has done excellent service to follow from its similarity to the equation for a

to teachers and students alike by publishing stretched string. Huyghens' principle of the superthis book, which fills a very obvious gap. It is an position of small motions is explained, and then the introduction to the theory, and purposely does not deal reader, after a chapter on the nature of light, is with details of methods of measurement or instru- introduced to the principle of interference. mental appliances; these are properly left to courses The problems of diffraction are treated very fully, of laboratory instruction. At the

time the making use of the method of Fresnel's zones; the necessity for experiments and observations is every method is modified by the author in a manner which where present to the author's mind. The book is not permits numerical results of a high order of accuracy a mere mathematical treatise on simple harmonic to be obtained without the introduction of Fresnel's a motion; indeed, the analysis is generally easy, and integrals. purely mathematical difficulties are avoided. Prof. After an interesting chapter on diffraction gratings Schuster writes as a physicist. The physical meaning we come to one on the theory of optical instruments, of the steps and processes employed is everywhere in which the resolving power of telescopes and insisted on, and the student is made to think through-spectroscopes is carefully discussed. The theory of out.

the microscope does not find

a place in Prof. The standpoint of the author is best explained by Schuster's book; perhaps it belongs rather to the two short extracts from his preface. After stating domain of geometrical optics. that the elastic solid theory of optics as developed Fresnel's theory of double refraction is given very in England by Green and Stokes has proved | fully, and it is based not on any unsound dynamical insufficient, he continues,

reasoning, but on the observed experimental fact " Those who believe in the possibility of a mechani

that the velocities of wave propagation of a plane cal conception of the universe, and are not willing wave moving through a crystal are given by the to abandon the methods which from the time of axes of the section of a certain ellipsoid by the plane Galileo and Needham have led uniformly and ex- of the wave; this is clearly the right way to deal clusively to success, must look with the gravest with this problem. When the laws of the propaga

a growing school of scientific thought tion of light in a crystal are once determined the diswhich rests content with equations correctly representing numerical relationships between different cussion of the rays and brushes due to the interser. phenomena, even though no precise meaning can be ence of polarised light follows easily, and thus we are attached to the symbols used.”

led to Part II., which, as has been already said, deals And again,

with theories of light. “ The equations which at present represent the

The equations of motion are found both on the electromagnetic theory of light have rendered elastic solid and electromagnetic theory, and the excellent service, and we must look upon them as a simpler phenomena are considered from both · standframework into which a more complete theory must points. necessarily fit, but they cannot be accepted as constituting in themselves a final theory of light.

The weak points of the elastic solid theory, how“ The study of physics must be based

ever, soon manifest themselves, and for the rest of knowledge of mechanics, and the problem of light the book the equations of the electromagnetic theory will only be solved when we have discovered the mostly used; in dealing with dispersion mechanical properties of the ether. While we Sellmeyers' hypothesis of sympathetic vibrations is in ignorance on fundamental matters concerning the applied to the electrons of a molecule, following origin of electric and magnetic strains and stresses, Drude, and the

Drude, and the usual expression connecting the it is necessary to introduce the theoretical study of light by a careful treatment of wave propagation refractive index and the frequency obtained; the same Through media the elastic properties of which are method is applied to explain the rotatory effects of known. A study of the theory of sound and of the sugar and other active substances, and in a most old elastic solid theory of light must precede there interesting series of sections the Zeeman and other fore the introduction of the electromagnetic equations." | allied effects are dealt with. In the last chapter

The book proceeds on these lines; the first part is we have a discussion on the nature of light as the almost entirely kinematical; the second part deals with resultant disturbance arising from the individual theories of light, starting first from an analysis o vibrations of the molecules of the source. Enough the equations of motion of an elastic medium; then has probably been said to show the nature of the passing to those of the electromagnetic field, and book, but one characteristic should not be omitted. developing the two theories side by side as . far as Prof. Schuster has included short historical accounts possible.

of the men who have made the science of physical To turn

some details. In the earlier optics. Among them we find the names of Young, chapters, in accordance with the views expressed in Fresnel, Cauchy, Stokes, and Maxwell; the interest

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