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ON SALE. Astronomical Telescope, with 4 in. clear aperture, altazimuth stand, 1 day and 4 astronomical eyepieces, price only £17; others cheaper.-Microscopes, second-hand by Zeiss, with substage and Abbé condenser, 2 eyepieces, 2 objectives and triple nosepiece, for £9. Another by PilliSCHER, with mechanical stage, substage-condenser and Iris-daphragm, 3 eyepieces, 3 objectives, viz. : 1", ", & 1" oil immersion, price only £6 10s. Another by Powell & LEALAND, with mechanical stage, substage-condenser, and seven objectives all “Pand L," offered for £10. Binocular Microscope by Swift, cost £40, offered at £10. Another by SrEWARD, with mechanical stage, 2 objectives, double nosepiece, &c., £6. Assay Balance by OERTLING, 6 in. beam, double columns, sensitive to to milligram, double rider, ccst £25, offered at £6. Others in Stock. 20 ft. Hydrogen Cylinder (charged), price £1. Scientific Lantern Slides on every subject at 5d, each. Microscope Slides on approval at 4d, each.

Rev. H. MILLS, Greenside, Kendal.

ELECTRICAL TESTING INSTRUMENTS.

DURHAM House, North SIDE, CLAPHAM COMMON, LONDON, S.W.

SCIENTIFIC WORTHIES.

With 30 Original Ilustrations. Price 25. 6d.
The HYGIENE of the MOUTH.
A Guide to the Prevention and Oontrol of Dental Diseases.
By R. DENISON PEDLEY, L.D.S. Eng., F.R.C.S. Ed.,
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BY THE SAMR AUTHOR.
The DISEASES OF CHILDREN'S TEETH

Well Illustrated. Price 75. 6d.
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SECOND-HAND
TELESCOPES, &c.-
61 in. ALVAN CLARK, equatorial, much apparatus

£150 6 in. COOKE,

do.
do.

£220 6 prism SPECTROSCOPE by BROWNING

£20 MICROSCOPES

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ZEISS IVa, ZEISS Vla

£14, £10
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1905

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MACMILLAN & CO.'S NEW BOOKS, . THE STATESMAN'S YEAR-BOOK,

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A MANUAL OF QUATERNIONS.

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8vo. 10s. net.

ELECTROMAGNETIC THEORY OF LIGHT.

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Part I. 8vo. 128. net.

THE HISTORICAL RELATIONS OF MEDICINE AND SURGERY TO THE END

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THE MICROSCOPE. JAMES R. GREGORY & CO., Kelso Place, Kensington Court, London, W., Volvox, Spirogyra, Desmids, Diatoms, Amoeba, Arcella, Actinosphærium, for a Prospectus of

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onium; Hormiphora (preserved); Leptoplana; Lineus, Ampbiporus, Nereis, Aphrodite, Arenicola, Lanice, Terebella; Lepas, Balamus

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Pectens Bugula, Crisia, Pedicellina, Holothuria, Asterias,' Echinus. Lepidoptera, Coleoptera, Tropical Butterflies, Cabinets, &c. Correctly Ascidia, Salpa (preserved), Scyllium, kala, &c., &c. nained type collections at very moderate prices.-- Particulars from For prices and more detailed lists apply to A. FORD, Hillside, Sunnyhill, Pokesdown, Bournemouth.

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THE DIRECTOR.

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C. E. MÜLLER, ORME & CO.'S NEW RESISTANCE GLASS

excels Jena Glass in its power to stand sudden variations of temperature. N. B. - The official test at the Charlottenburg Institute showed that with this glass the alkali dissolved by 100 c.c. of distiller water is , !, milligrammes as compared with dir milligrammes dissolved from Jena glass under the same conditions.

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Rio de Janeiro, To

Nov. 7th, 1904.
Messrs. Sanders & Crowhurst,

London.
Gentlemen,

I have much pleasure in writing to inform you that my “Birdland” Camera is proving a great success in the tropical heat of this country.

As you know I was feeling a little doubtful when I left England, as to how the camera would stand all the great climatic changes that it would have to pass through with me on my travels. However, it has come through with flying colours, and has not once failed me. Moreover it has enabled me to obtain a large number of successful negatives that could only have been gained with the aid of a reflex camera.

Your faithfully, (Signed) F. MARTIN-DUNCAN.

BEST PATTERN.
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OPTICAL CONVENTION, 1905.

BIRKBECK COLLEGE.

BREAMS BUILDINGS, CHANCERY LANE, E.C.
President :

FACULTY OF SCIENCE.
Dr. R. T. GLAZEBROOK, M.A., F.R.S.,

DAY AND EVENING COURSES.
Director of the National Physical Laboratory.

Chemistry
Vice-Presidents:

J. E. MACKENZIE, Pà. D., D.Sc.

(H, WAEN, Ph.D., BA. B.S. Sir WM. DE WIVELESLIE ABNEY, K.C.B., D.C.L, F.R.S.

(ALBERT GRITTITHS, D.Sc. The RIGHT HON. THE LORD BLYTHSWood.

Physice ...

D. OWEN, B.A., B.Sc.

18. w Clack, B.Sc.
Sir W. H. M. CHRISTIE, K.C.B , M.A., F.R.S.,

Astronomer Royal.
Mathematics

E. H. SMART, M.A.

(W.G. BIRT, B.A., B.Sc. The Right Hon. The EARL OF CRAWFORD, K.T., LL.D., F.R.S.

Botany
MR. Thos. R. DALLMEYER, F.R.A.S.

F. E. FRITSCH, Ph.D. B.Sc
The Hon. ALBAN G. H. Guess, M.A., M.P.,

Zoology ..

H. W. UNTHANK, BA, B.Sc
Master of the Worshipful Co. of Spectarle Makers.

Qeology & Mineralogy Geo. F. HARRIS, F.G.S.
Sir HOWARD GRUBB, F.R.S.

Assaying, Metallurgy & Mining. Geo. PATCHIN, A.R.S.M The Right Hon. THE LORD KELVIN, O.M., G.C.V.O., F.R.S. RESEARCH in Chemistry and Physics in well-equipped laboratories THE RIGHT Hon. The I ORD RAYI EIGH, O.M., D.C.L., F.R.S. French, German, Spanish, Russian, Dutch, & Itallan Classes. THE Right Hon. The EARL OF ROSSE, K.P., D.C.L., F.R.S.

EVENING CLASSES also in Biology, Physiology, Practical Geometry.

Building and Machine Construction, Steam, Theoretical and Applica
TH
HE OPTICAL CONVENTION will be held at the North

Mechanics, Land and Quantity Surveying, and Estimating.
AMPTON INSTITUTE, CLERKENWELL, E.C., from May 31 to
June 3, inclusive.

Calendar 6d. (post free 8d.), on application to the SECRETART. The object of the Convention is to bring into co-operation those interested in Optical Matters, from all sides of the question, theo- At the SOUTH-WESTERN POLYTECHNIC, retical, practical, and commercial,

Manresa Road, Chelsea, S.W., Day College Courses of thirty boun The mornings will be devoted 10 papers and discussions on Optical subjects. These will be collected in a volume 10 be issued by the

per week are conducted in preparation for the London University

Degrees of B.Sc. in Mechanical and Electrical Engineering, in Chemis Convention.

try, Physics and the Natural Sciences. The composition fee for the There will be an

Session of three terms, 1904-1905. is 615. These Courses are reorgs EXHIBITION OF OPTICAL & SCIENTIFIC INSTRUMENTS nised for "Internal Students of the University, and consist of

lecture and laboratory instruction. The Crurses are conducted by of British manufacture, in the large ha!) of the Northampton Institute, MECHANICAL ENGINEERING, W. W. F. Pullen, A. Mack during the Convention, open daily from 12 to 10 p.m. In connection

Smith; ELECTRICAL ENGINEERING, A J. Makut with this, a catalogue is in preparation, which will be a useful work CHEMISTRY, J. B. Coleman, J. C. ('rocker, and F. H. Lase; of reference in regard to instruments manufactured in this country.

MATHEMATICS and PHYSICS, S. Skinner, W. H. Eccles, J. Lister The Subscription for Membersbip of the Convention will be five and L. Lownds; BOTANY, H. B. Lacey and T. 6. Hill: shillings. Applications for membersbip should be aodressed to the GEOLOGY, A. J. Maslen. In the evenings similar Courses will be Hon. Sec., Mr. F. J. SELBY, M.A., Elm Lodge, Ieddington,

conducted, but at fa per Session. Also TECHNICAL DAT Middlesex, who will be glad to furrish suriber particulars if desired.

COURSES of three years' duration are arranged as a preparation for

the Engineering, Electrical and Chemical and Metallurgical pro ADMISSION to the Exhibition, daily, ONE SHILLING, lesions. The Laboratories and Workshop are open for RESEARCH after 7 p.m., Sixpence.

under the direction of The Principal and the Heads of Departments Tickets admitting to the Exhibition at any time while it is open, 2/6.

Further particulars may be obtained on application to The SECRETARY, who will send either the Day College Prospectus arc Calendar or the Evening Class Prospectus for 34«. The Prospectus may be had at the Office for id, each.

OF

ROYAL INSTITUTION

GREAT BRITAIN.

success.

ALBEMARLE STREET, PICCADILLY, W. MONDAY, May 1, at Five o'clock, Annual Meeting of the Members.

TUESDAY, May 2, at Five o'clock, Professor L. C. MALL, D.Sc., F.R.S., first of Three Lectures on “The Study of Extinct Animals." Half-a-Guinea the Course.

THURSDAY, May 4. at Five o'clock, Professor Sir JAMES DEWAR, M.A., LL D., D.Sc., F.R.S., first of Three Lectures on " Flame." Half-a-guinea.

SATURDAY, May 6, at Three o'clock, Professor MARSHALL Warn, D.Sc., F.R.S., first of Two Lectures on “Moulds and Mouldiness." Half-a Guinea.

Subscription to all the Courses in the Season, Two Guineas.

FRIDAY EVENING, May 5. at Nine o'clock, Professor HENRY E. ARMSTRONG, Ph.D., LL.D., F.RS, on “ Problems Underlying Nutrition.' (UNDER THE AUSPICES of His MAJESTY'S GOVERNMENT.) THE LONDON SCHOOL OF TROPICAL

MEDICINE.
(UNIVERSITY OF LONDON.)
CONNAUGHT ROAD, ALBERT DOCK, E.
(IN CONNECTION WITH THE HOSPITALS OF THE SEAMEN'S

Hospital Society.)
The next SESSION commences on MONDAY, MAY 1, 1905.

For Prospectus, Syllabus, and other particulars, apply to the Secretary,
P. MICHELLI, Esq., Seamen's Hospital, Greenwich, S.E.

B.A. AND B.Sc. EXAMS.

MATRICULATION, INTERMEDIATE, FLVAL. PREPARATION by CORRESPONDENCE and ORAL TUITION on a THOROUGHLY INDIVIDUAL SYSTEM. Fees based ca

The STAFF includes Graduates of Oxford, Cambridge, London, and
Royal V'niversities, Science Medallists, Prizemen, Scholars, &c.

SINGLE SUBJECTS TAKEN: Science, Mathematics, Love,
Psychology, Political Economy, Latin, Greek, French, German, &c.

for terms, &c., address Mr. J. CHARLESTON, B.A. (Lond. and Oxod. Burlington Correspondence College, Clapham Common, London, SW. UNIVERSITY OF BIRMINGHAM

FACULTY OF SCIENCE.
PROFESSORSHIP OF CIVIL ENGINEERING.
The Council of the University wish to elect a Professor of Cir
Engineering to co-operate with the Professors of Mechanical and Electrici
Engineering. He will have charge, with an assistant, of the teaching of
Surveying, Strength of Materials, Hydraulics, and other branches of Civil
Engineering, and will superintend ihe laboratories for Hydraulics and
Strength of Materials.
The Stipend will be $600 a year.

The Professor will be allowed to take Higher Consultative work, to kee? in touch with Civil Engineering practice, provided that it does not intolat with his University duties.

Applications, accompanied by seventy five copies of testimonials, shoeli be received by ihe Secretary, not later iban May 20.

The successful Candidate will be expected to begin his duties -
October 2, 1905.
Further particulars may be obtained from

GEO. H. MORLEY, Secretary UNIVERSITY OF LONDON. WILLIAM LINDLEY STUDENTSHIP. A Research Studentship Physiology of the value of £100 for one year, founded in memory of their late William Lindley and tenable in tbe Physiological Laboratory of University. is now vacant. Applications, accompanied by a summary or the career of the applicant and the names of three persons to whom refere may be made, will be received by the undersigned on or before Mandar May 8 next.

A, W. RUCKER, Principal University of London, South Kensington, S.W.

for other Scholastic Advertisements, see page cexly.

BACTERIOLOGY and PATHOLOGY. KING'S COLLEGE, LONDON. Director-R. T. HEWLETT, M.D., Professor of Bac'eriology.

Demonstrator of Bacteriology--H. S. Willson, M.B. The Laboratories are open daily from April 26 for instruction and research in Pathology, Bacteriology, and Public Health.

Students may enter at any time.

A Course in Clinical Bacteriology suited to the requirements of senior students for the M.B. degrees will be held on Tuesdays and Thursdays during the summer session. Fee £5 55.

For Syllabus apply to the SECRETARY or to Prof. HEWLETT,