SIR WILLIAM THOMSON'S PATENT INDESTRUCTIBLE WATER TAPS.

THESE TAPS have been opened and closed under water pressure for the equivalent of more than 50 years (30 times a day) without any deterioration. The ordinary rubber, fibre, or leather washer valve, and the packing or washer around the spindle, are entirely dispensed with. Perfect watertightness is nevertheless atta ined.

By the invention of this indestructible water tap Sir William Thomson, D.C.L., LL.D., President of the Royal Society, &c., the author of many other useful inventions, has effected what previous inventors have unsuccessfully attempted. By an ingenious device the metallic valve and its seat retain their burni-hed condition for an indefinite period. The taps are made of the best metal throughout, and are equally suitable for boiling and cold water, are tested to 300 lbs. per square inch before leaving the works, and are sold at a lower price than equal qualities of ordinary firms by the

PALATINE ENGINEERING CO., LTD., 10 Blackstock St., Liverpool,

SOLE LICENSEES.

Descriptive Pamphlets and Prices on application

Works in any Weather. Best made, Studded Plates.

WITH 15-INCH PLATES, £4 10

O

5 10 O

MACMILLAN & CO.'S NEW SCIENTIFIC BOOKS.

BY J. L. KIPLING, C.I.E.

Just Ready, 8vo, 21s.

BEAST AND MAN IN INDIA. A Popular Sketch of Indian Animals in their Relation with the People. By JOHN LOCKWOOD KIPLING, C.I.E.

BY W. J. MCCLELLAND, M.A.

Just Ready, Globe 8vo, 6s.

With many Illustrations by the Author.

A TREATISE ON THE GEOMETRY OF THE CIRCLE, AND SOME With numerous Examples

EXTENSIONS TO CONIC SECTIONS BY THE METHOD OF RECIPROCATION. by WILLIAM J. MCCLELLAND, M.A., Principal of Santry School, Dublin.

8vo, Price advanced to 15s. net.

THE THEORY OF LIGHT. By THOMAS PRESTON, M.A., Trinity College,

Dublin.

SPEAKER:-"It is the very model of what an advanced text-book ought to be, and the mathematical proofs are given with a crispness and simplicity which furnish a continual treat." SPECTATOR:-"A decidedly clear, straightforward, and exact treatise."

SATURDAY REVIEW:—“A remarkably clear and concise exposition of the undulatory theory as it stands at the present time."

SECOND PART OF LOEWY'S COURSE OF NATURAL SCIENCE.
Just Ready, Globe 8vo, Cloth, 2s. 6d.

GRADUATED COURSE OF NATURAL SCIENCE, EXPERIMENTAL AND THEORETICAL, for Schools and Colleges. Part II. Second and Third Years' Course for the Intermediate Classes of Colleges and Technical Schools. By BENJAMIN LOEWY, F.R. A. S., &c. With Sixty Diagrams.

BY WILLIAM SMART, M.A.

Just Published, Crown 8vo, Cloth, 3s. net.

AN INTRODUCTION TO THE THEORY OF VALUE, on the lines of
Menger, Wieser, and Böhm Bawerk. By WILLIAM SMART, M.A., Lecturer in Political Economy in Queen
Margaret College, Glasgow; Translator of Böhm Bawerk's "Positive Theory of Capital," and " Capital and Interest."
TRANSLATED BY THE SAME.
8vo, 12s. net.

THE POSITIVE THEORY OF CAPITAL. By EUGEN V. BÖHM BAWERK,
Counsellor in the Austrian Ministry of Finance, and Honorary Professor of Political Economy in the University of Vienna.
Translated, with a Preface and Analysis, by WILLIAM SMART, Lecturer on Political Economy in Queen Margaret College,
Glasgow.

admirable.

TIMËS:—“Mr. Smart has done his work excellently. His preface, analytical digest, and the actual translation are all We have to thank him for rendering accessible to English students a treatise which is certainly well worth attention as a specimen of contemporary Continental thought, and which, although its central theory is based, as the author frankly avows, upon certain ideas of Jevons, has carried those ideas further and given them a special application."

MACMILLAN AND CO., LONDON.

ON SALE BY MACMILLAN AND BOWES,

CAMBRIDGE.

CLAPIN, A. C.—Optical Problems. 8vo. 1850. 35.
DE MORGAN, A.-The Book of Almanacs, with an Index
of Reference, by which the Almanac may be found for every year, from
any Epoch, up to A.D. 2000, &c. 2nd edit. Cloth. 1871. 65.

EARNSHAW, S.-The Doctrine of Germs, or the Integra-
tion of certain Partial Differential Equations which occur in Mathe-
matical Physics. 8vo. 1881. 35.

ELLIS, R. LESLIE [1817-59].-Mathematical and other Writings. Edited by Wm. Walton. Memoir by Harvey Goodwin (now Bishop of Carlisle). Portrait. 8vo, Cloth. 1863.

125.

GREGORY, DUNCAN F. [1813-44].-Mathematical
Writings. Edited by W. Walton, with Memoir by R. Leslie Ellis.
Portrait. 8vo, Cloth. 1865. 8s.

NEWMAN, F. W.-The Difficulties of Elementary Geo-
metry, especially those which concern the Straight Line, the Plane, and
the Theory of Parallels. 8vo. 1841 (pub. 8s.). 2s. 6d.

THE MATHEMATICAL MONTHLY. Edited by J. D. RUNKLE. Complete in 3 vols. Royal 8vo. Cambridge, Mass., 1859-61. 385.

This journal, now scarce, was discontinued at the time of the American Civil War. Contains contributions by P. E. Chase, G. B. Bond, Prof. Pierce, W. D. Henkle, Elias Loomis, S. Newcomb, A. Cayley. J. E. Oliver, T. H. Safford, W. Watson, E. B. Elliott, Chauncey Wright, W. Chauvenet, W. Ferrel, Matthew Collins, C. H. Davis, and others.

AWARDED-2 GOLD MEDALS, Paris Universal Exhibition, 1889; 2 DIPLOMAS OF HONOUR for MICROSCOPES and MICROSCOPIC OBJECTS, Antwerp International Microscopical Exhibition, 1891; and 24 GOLD AND OTHER MEDALS at the Principal International Exhibitions

MICROSCOPES.

The Van Heurck Microscope (Registered). Designed specially by WATSON & SONS to the Specification of Dr. Van Heurck, of Antwerp, for his delicate high-power work and photography. The Edinburgh Student's Microscope. Made in four forms, suitable for the Amateur, Student, or Professor. Price from £3 10s.

The Scientist's Microscope.

A largest-size Microscope, with all latest improvements and every convenience for work.

of the World.

FULL ILLUSTRATED CATALOGUE OF MICROSCOPES AND APPARATUS. JUST PUBLISHED NEW CLASSIFIED LIST OF MICROSCOPIC OBJECTS. Either of the above Catalogues sent Post Free on application toW. WATSON & SONS, OPTICIANS TO HER MAJESTY'S GOVERNMENT, 313 HIGH HOLBORN, LONDON, W.C.

AND 251 SWANSTON STREET, MELBOURNE, AUSTRALIA.

HYGIENIC"

WOOLLEN SYSTEM

OF

UNDERWEAR.

FOR LADIES, GENTLEMEN, AND CHILDREN.

Samples and Illustrated Catalogues, containing full particulars, sent on receipt of inquiry, post free.

As Manufactured and Exhibited by us at the INTERNATIONAL EXHIBITION, GLASGOW. The spontaneous and hearty testimony borne by the medical faculty to the merits of our makes of Underwear is without doubt a most gratifying confirmation of the claims we have advanced in its favour.

Excerpts from Press Opinions

"We find special merit in the Forsyth undergarments. These embrace every article almost that a lady, gentleman, or child may wear, and are beautifully made and neatly finished."-The Queen.

"The samples from this firm are eminently satisfactory. The elastic woven vests give great choice of thickness; the very thin ones might be worn without any discomfort in the hottest summer, while the thicker varieties afford ample protection against cold, and yet retain a smoothness of texture which prevents any irritating friction, and, from the unshrinkable nature of the material, will be found far more useful for underwear than most ordinary flannels. They are very gratifying examples of home manufacture."-Lancet.

"Forsyth's hygienic underwear for adults and children of both sexes are splendid for comfort, warmth, and wear. Heads of households will do well to send (to Glasgow) for samples of these goods and judge for themselves."-The Lady.

Excerpts from Customers' Letters.

"I have now found the right material in your Hygienic. It cannot be surpassed."

"The Hygienic' underwear has given great satisfaction, and has not shrunk in the least."

"For comfort, style, and durability of wear, the 'Hygienic' garments are the best I ever had."

"The children's Hygienic combinations give great satisfaction, and have worn well."

"I have very much pleasure in testifying to the excellence of your Hygienic' underwear."

"I am much pleased with the Hygienic 'underwear, and feel great comfort in their wear."

"

"The Hygienic combinations made to order are very nice, and fit well."

"The Hygienic' underwear got three years ago were found so comfortable."

FORSYTH, RENFIELD ST., GLASGOW.

Printed by RICHARD CLAY AND SONS, LIMITED, at 7 and 8 Bread Street Hill, Queen Victoria Street, in the City of London, and Published by

MACMILLAN AND Co., at 29 Bedford Street, London, W.C., and 112 Fourth Avenue, New York.-THURSDAY, November 26, 1891.

Crossley's New High Speed Engine
for Electric Lighting. Can be used for
other purposes when not so engaged.

CROSSLEY BROS., Ltd.,

Openshaw, Manchester.

Registered as a Newspaper at the General Post Office.]

NEWTON'S PATENT

[All Rights are Reserved.

Scientist's Biunial Lantern, NALDER BROS. & CO.,

Cambridge and London University
Extension Lecturers, &c.
Highest quality only, £14 145.
New Catalogue of Optical Lanterns,
Projection Apparatus, and Scientific
and other Slides, Four Stamps.
NEWTON & CO.,
Opticians to the Queen and
the Government,

By Special Appointment

TO THE ROYAL INSTITUTION OF GREAT

3 FLEET STREET, LONDON.

16 RED LION STREET,

CLERKENWELL, LONDON, E.C.

TELEPHONE NO. 6770. TELEGRAPHIC
ADDRESS: SECOHM, LONDON.

NEW PATTERN BALLISTIC

GALVANOMETER.

Resistance 10,000 Ohms.

Prices

and full particulars

on

application.

HYDROCARBON BLOWPIPE AND FURNACES.

he attention of ASSAYERS, ANALYSTS, DENTISTS, &c., is called to this apparatus with perfect confidence as to its merits.

ADVANTAGES.

No DEST PORTABLE! NO ASHES! AUTOMATIC! PRACTICAL!

ECONOMICAL!

Laboratory Blast Lamps, £2 28, and £3 38.
Crucible Furnaces, £5 138., £6 6s., £7 188, 6d.
Muffle Furnaces, £6 18s., £7 19s.
Full Particulars upon Application.

JOHN J. GRIFFIN & SONS, L 22 GARRICK STREET, COVENT GARDEN, LONDON, W.C.

Aneroid Barometer with Altitude Scale, Compass with Patent Dial and Thermometer for Air Temperatures (or a Clinical Thermometer may be substituted).

PRICE £4 10s. to £7 10s.

ILLUSTRATED PRICE LISTS POSTED FREE TO ALL PARTS OF THE WORLD.

NEGRETTI & ZAMBRA,
SCIENTIFIC INSTRUMENT MAKERS TO THE QUEEN,
38 HOLBORN VIADUCT.

Branches: 45 CORNHILL; 122 REGENT STREET.
Negretti & Zambra's Illustrated Catalogue, 1200 Engravings, Price 5. 6d
Photographic Studio-CRYSTAL PALACE, Sydenhan.
Telephone No. 6583. Telegraphic Address: "Negretti. London"

CHRISTMAS LECTURES.

ROYAL INSTITUTION OF GREAT

BRITAIN,

ALBEMARLE STREET, PICCADILLY, W.

Prof. JOHN G. McKENDRICK, M.D., F.R.S., will deliver a Course of Six Lectures (adapted to a Juvenile Auditory) on "Life in Motion, or the Animal Machine" (experimentally illustrated), commencing on TUES. DAY, DECEMBER 29, 181, at Three o'Clock; to be continued on December 31; and January 2, 5, 7, 9, 1892.

Subscription (for Non Members) to this Course, One Guinea (Children under Sixteen, Half-a-Guinea); to all the Courses in the Season, Two Guineas. Tickets may now be obtained at the Institution.

BEDFORD COLLEGE, LONDON (FOR WOMEN),

8 and 9 YORK PLACE, BAKER STREET, W.

TRAINING DEPARTMENT.

Head of the Department :-Miss M. V. THOMAS, B.A. Lond.,
Teacher's Training Certificate, Cambs.

This Department provides a Professional Training in Teaching for Women.
The course of instruction includes Lectures on Psychology, Theory and
History of Education, Art of Teaching, &c., and practical work in various
schools, covering all the ground required to obtain the Teacher's Diploma.
Further particulars can be obtained from

LUCY J. RUSSELL, Honorary Secretary.

KING'S COLLEGE, LONDON. EVENING ELECTRICAL ENGINEERING LECTURES AND LABORATORY WORK.

A New Course will begin on MONDAY, JANUARY 18. For Particulars, apply to J. W. CUNNINGHAM, Secretary.

NATUR E.-Vols. I. to XXXI., Plates,
Uniform Green Cloth. Price 10 Guineas.

W. A. BAILY, Cirencester.

Now Ready, Price 5s. net, Demy 8vo.

ANNALS OF BRITISH GEOLOGY, 1890.

LIVING SPECIMENS FOR THE
MICROSCOPE.

Volvox globator, Melicerta ringens, Floscularia ornata, Megalotrocha albo-flavicans (a very rare, clustered Rotifer), Lophopus crystallinus, and other "Pond-life." Amoeba, Amphioxus, and other specimens for Laboratory Work. Specimen Tube, 1s., Post-free.

THOMAS E. BOLTON,
FARLEY ROAD, MALVERN.

CONCHOLOGY.

New and Interesting Shells from New Guinea,
Borneo, Philippine Islands, &c.

COLLECTIONS PURCHASED.

All kinds of Glass-Topped Boxes, &c., at Moderate Prices. HUGH FULTON, Dealer in Recent Shells, 89 FULHAM ROAD, LONDON, S.W.

MODELS OF DIAMONDS.

As exhibited in the Loan Collection in South Kensington

Museum.

1.-Facsimiles of 28 of the most celebrated White and Coloured Diamon ds executed in Crystal Glass, of great lustre, to which has just been added a Model of the Black (unique) Diamond of Punnah, in the possession of the Mabarajah of Punnah, in handsome Morocco Case with descriptive Catalogue. Price £10 105.

2.-30 Models natural Crystals of Diamonds and Coloured Precious Stones, artistically and beautifully cut in imitation of originals, exhibited in Paris Exhibition of 1878, and obtained the Bronze Medal: in handsome Morocco Case. Price £6 6s.

Richly gilt Model and facsimile of the "Welcome" Gold Nugget, of Australia, largest known. Original weight 2166 oz. Value of the Gold, L8376 10s. 10d. Price £3 35., or in handsome Glass Shade, 22 x 11, £5 55. Set of imitations of "Precious Stones in Morocco Case, 48 sp., Price Address-ROBERT F. DAMON, Weymouth.

308.

F. H. BUTLER, M.A. Oxon., Assoc.R.S. Mines,

NATURAL HISTORY AGENCY,

158 BROMPTON ROAD, LONDON, Dealer in Rocks, Minerals, Fossils, and other Objects of Scientific Interest.

Now on view: numerous recently acquired Jurassic fossils, Chalk Echinoderms, including Marsupites from Burpham; a fine series of palatal teeth of Halodus, Sandalodus, Oracanthus, Tomodus, Deltodus, and Orodus, besides a large collection of well-characterized corals from the Black Rocks of Clifton, Bristol, now no longer worked; also excellent examples of Tremadoc Trilobites, e.g. species of the genera Neseuretus and Angelina, from Garth, Og of Velvet, and other classical localities; and Devonian fish-remains from Caithness and Banff. Among the recent additions to the stock of minerals are various old Cornish species, and a few Gloucestershire Celestines of abnormal habit.

COLLECTIONS OF MINERALS,
ROCKS, OR FOSSILS,

For the Use of Students, Science Teachers, Prospectors, &c., and to
illustrate the leading Text-books, in Boxes, with Trays.

50 Specimens, 10s. 6d. ; 100 do., 21s.; 200 do., 42s. New Price List of Minerals, Rocks, and Stratigraphical Series of Fossils Post Free.

ROCK SECTIONS for the MICROSCOPE from 15. 6d. each, Post Free
CATALOGUES GRATIS.
CABINETS, GLASS-CAPPED BOXES, TRAYS, HAMMERS, &c.,
always in Stock.

A Critical Digest of the Publications during the Year, with Personal THOMAS D. RUSSELL,

Items. By J. F. BLAKE, M.A., F.G.S.

London: DULAU & CO.

78 NEWGATE STREET, LONDON, E.C.