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NEW PAN-APLANATIC OBJECTIVES

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BOROUGH OF SWINDON.

JAMES SWIFT & SON'S
EDUCATION COMMITTEE.

OF THE HIGHEST POSSIBLE OPTICAL EXCELLENCE. The Committee REQUIRE the services of an ASSISTANT SCIENCE

Apochromatics. DEMONSTRATOR in the HIGHER ELEMENTARY SCHOOL.

" N.A.,1.30, oil immersion

... £8 80 Candidates must be accustomed both to Class Teaching and Laboratory Work. Commencing salary £120 a year, increasing by 65 a year to 6160.

» 1.40
12"
» 1.40

. Forms of application, which must be returned by September 15, may be

.. 8 8

"Pan-Aplanatics. had from

W. SEATON, Secretary.

}" oil immersion, N.A., 1.30 ... Education Office, Town Hall, Swindon.

, 1.30
1.30

5 5 0 August 29, 1905.

Dry'series Pan-Aplanatics. " N.A., 0.30 ... ... £2 5 0 1 N.A., o. 80 ... . 1 16 0 0.50

0

... MASTERSHIPS VACANT FOR SEP

,, 0.88

2 ...

17 0 030...

I!" 092 ... ... 2 0 0 TEMBER.-Geology. Botany. Zoology. Canada. 6200. Passage.

5 Nature says :-"In the excell_nce of their 1/12-in. homogeneous Board and 3 Rooms. Chemistry, Physics. Ireland, College, £250.

oil immersion, they have pro luced an English-made lens of first-rale Several Science Graduates, Public College, London University Teach

capacity which is a marvel of cheapness." ing Centre, 6150 to 6300; Ditto, Mathematical, £150 to 6300; Eng. lish, must be in Honors, £150 to £175; English and French, 6150 to

LISTS POST FREE ON APPLICATION. £175; 200 Vacancies for Senior, Junior, and Foreign.

UNIVERSITY OPTICAL WORKS, ORELLANA & CO.

81 Tottenham Court Road, London. Send List to all Candidates,

GLEW'S SCINTILLOSCOPE 80 WIGMORE STREET, LONDON, W.

(PATENT).

Shows a magnificent display of scintillations, KING'S COLLEGE, LONDON.

showers of sparks, direct from the mineral Pitch. blende, Radium, Polonium, Uranium, Thorium, or

any radio-active substance, even a Welsbach mantle (UNIVERSITY OF LONDON.)

contains sufficient Thorium to excite the very sensi The Council invite applications for the post of JUNIOR DEMON.

tive screen of the Scintilloscope, which is far more

sensitive than the Spinthariscope. STRATOR in ENGINEERING.

The Scintil. Applications should be sent in by Friday, September 15, 1905.

loscope rivals the most delicate Blectroscope as a

detector of Alpha rays.

SCREEN For conditions apply to

The eye sees an inexhaustible shower of stars of WALTER SMITH, Secretary.

PITCHBLENDE white light, giving a very realistic idea of the cease.

less activity of these marvellous substances which KING'S COLLEGE.

are producing the terrific bombardment causing this beautiful display.

r See NATURE, September 29, page 535.. (UNIVERSITY OF LONDON.)

Glew's Scintilloscope Superior Lens, with Extra-sensitive Pitchblende and

Polonium Screens, giving brilliant effects, Complete, 75. 61, Post free, DEMONSTRATOR in ZOOLOGY wanted for October, 1905. Salary, U.K. Foreign Postage extra, weight 2 ounces. 6150. For further particulars apply to the SECRETARY, King's College, Pieces of Pitchblende mineral, ground flat and polished, with Sensitive Strand, W.C.

Screen attached, for use in Scintilloscope or with any strong pocket

magnifier, from 75. 6d. each, according to size.

Radio-active supplies of every description, on Sale or Hire. Radium MERCHANT VENTURERS'

Bromide 1,800,000 units on hire for lectures.

F. HARRISON GLEW, Radiographer (Silver Medallist, Paris, 1900), TECHNICAL COLLEGE, BRISTOL.

156 Clapham Road, London, S.W. ASSISTANT LECTURER and DEMONSTRATOR in ENGINEER. ING required. Salary, $170, wbich may rise to 6220. Particulars

BUTLER'S obtainable from the REGISTRAR by sending a stamped addressed foolscap envelope. Applications should be sent in not later than Sep'ember 18, 1905.

“SWINGCAM" STAND. To SCIENCE and MATHL. MASTERS. REQUIRED immediately for Secondary School near London, Master

A SPECIALITY IN TRIPODS. to take Elementary Science and Geograp' y. 150 to commence. Also Mathl. Master for School in W. London. Matbs., including New

TESTIMONIAL
Geometry. £120. Many other vacancies.-Addres GRIFFITHS,
SMITH, Powell & SMITH, Tutorial Agents (Estd. 1833), 34 Bedford

from Mr. R. KEARTON, F.z.s. Street, Strand, London.

Caterham Valley. Surrey, August 4th, 1906

Dear Mr. Butler, Wanted for St. Augustine's Seminary, Dun

I have much pleasure in stating that I have put your new "Swingcam

Camera Stand through a series of severe tests in Natural History Photo garvan, Co. Waterford, a Teacher of Chemistry and Physics. Must be graphy, and found it an excellent contrivance for securing pictures under a B.Sc. with honours in Chemistry. Salary [140. Non-resident.

every conceivable difficulty of situation. Bird-photographers will find it a To take up his duties before October 15.

great boon.
Wishing it and those who use it all good luck,

I remain, Yours ever faithfully.
Newbold Rectory, Stratford-on-Avon.-Home

WM. BUTLER, Esq.

R KEARTON School for a limi'ed number of pupils. Science a speciality. Laboratory

WRITE FOR PAMPHLET AND PRESS COMMENTS. and Observatory. Fees moderate.-Apply G. A. S. ATKINSON, B.Sc. (Lond.).

WM. BUTLER, 20 Crosby Road, Southport. DUBLIN UNIVERSITY.

CHEMICALS SENIOR DEMONSTRATOR of PHYSIOLOGY wantel. Commencing salary, £175. Applications to REGISTRAR, Medical Schoul.

METALS For other Scholastic Advertisements, see pages clxxviii, clxxix, clxxx, and clxxxi.

MINERALS LABORATORY TOLET.-Large well

For Laboratory, Scientific, and all other filted Chemical Laboratory in neighbourhood of Hampstead, to te let temporarily. Electric power. Use of telephone.

purposes.

Apply Box 1871, Office of NATURE, St. Martin's Street, W.C.

RADIUM SALTS & RADIO-ACTIVE PREPARATIONS. SCIENTIFIC APPARATUS TRADE. CALCIUM METAL, 1/6 oz.; 20,- lb. Advertiser, 26, experienced and well qualified, desires change. - Apply

Price List on Application.
Box 71, NATURE Office.
To Science Masters, Curators of Museums, &c

HARRINGTON BROS., - Advertiser requires post as Assistant. Has knowledge of Geology

Chemical Manufacturers and Dealers, and Mineralogy.-Apply C. TAYLOR, 137 Dalling Road, Ravenscourt Park, W.

| 4 OLIVER'S YARD, CITY ROAD, LONDON, E.C.

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RARE

IMPORTANT REDUCTION IN PRICE.

SPINTHARISCOPE.

HOPKIN & WILLIAMS, Ltd.
16 CROSS STREET, HATTON CARDEN, LONDON, E.C.

Works-ILFORD, E.
PURE CHEMICALS
For TEACHING, RESEARCH, and TECHNOLOGY.

REVISED PRICE List.

AS DRVISED BY
SIR WILLIAM CROOKES.
Showing the Scintillations of Radium.
Price with powerful Lens, and contained in
neat Leather case, 15/- Post free anywhere.

The scintillations seen in this instrument are from Pure Radium Bromide of the highest known activity, and are brighter and more plentiful than those produced from Pitch blende or other bodies of low Radio Activity.

Ir See letter from PROF. Gotch on " The Spinthariscope and Retinal Excitability" (NATURE, June 22, 1905, page 174), setting forth a valuable scientific application of the instrument.

A. C. COSSOR,
54 FARRINGDON ROAD, LONDON, E.C.

Telephone, 10547 Central.
Gold Medal St. Louis Exhibition, 1904.

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OF

ELECTRICAL TESTING INSTRUMENTS.

DURHAM House, North Side, CLAPHAM COMMON, LONDON, s.w.

SCIENTIFIC WORTHIES.

SEND FOR DETAILS OF OUR
MICRO-SLIDE LENDING

DEPARTMENT.
Covering every Branch of Natural Science.
SUBSCRIPTION £1:1:0) FOR 240 SLIDES.
Over 58,000 Slides have already been circulated.
Is The Boxes are accompanied by descriptions of their contents,

concisely written by well-known authorities in the different

departments. C. BAKER, 244 HIGH HOLBORN, LONDON, W.C.

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.

TYPE-WRITING UNDERTAKEN BY

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, io Duke Street, Adelphi, W.C.

VOUNOT

HEELE'S FAMOUS
DIRECT VISION SPECTROSCOPE
With 10 prisms. Dispersion: 25°.

Price £17 nett.
The Telescope has Micrometer-screw with divided drum for Wave-

Lengths measurements.
Do. Do. with 5 prisms, dispersion 12o.

Price £13 15s. nett.
ADVANTAGES : Always adjusted and ready for use.

Illustrated Catalogues free on application.
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AS SUPPLIED TO THE
Royal College of Science, South Kensington, London, S.W.
University College, Gower Street, London, S.W.
South-Western Polytechnic, Chelsea, London, S.W.
Battersea Polytechnic, Battersea, London, S.W.
Woolwich Polytechnic, Woolwich, London, S.E.

PETER HEELE, 115 High Holborn, London, W.C. Maker of Physical, Chemical, and other Instruments, and every

kind of Spectroscope and Polarimeter. GRAND PRIX, PARIS, 1900; ST. LOUIS, 1904.

Telegrams: “ARCTITUDE, LONDON.”

DEPREZ SIGNAL, CARL ZEISS,

JENA.

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SINGLE OR

DOUBLE. A style for writing on smoked paper is attached to the armature of an electromagnet, and when the magnet is excited the style suffers a small displacement of adjustable amount. The apparatus is very small with extremely light moving parts. It is readily clipped to the stem (10 mm. diameter or under) of a simple stand, and fine adjustment is provided for bringing the style up to the paper. In the double form (as illustrated) two styles with independent electro-magnets are mounted side by side. If desired, one may be connected with a pendulum or tuning. fork interrupter to mark time while the other registers the events to be investigated. SINGLE DEPREZ SIGNAL,

complete in box, £2 10s. DOUBLE DEPREZ SIGNAL,

complete in box, £3 10s. THE CAMBRIDGE SCIENTIFIC INSTRUMENT COMPANY, LTD.,

CAMBRIDG E, ENGLAND,

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FOCAL

OF

PLANE

LICHT

SHUTTER,

METAL.

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THE JUBILEE CATALOGUE

FIFTY YEARS' EXISTENCE OF THE FIRM

OF

E. LEYBOLD'S NACHFOLGER,

R. FRIEDLÄNDER & SOHN,

BERLIN, N.W.6.
PUBLISHED ON AUGUST 24TH.

ISSUED TO MARK THE
ZOOLOGISCHER JAHRESBERICHT
Für 1904, red. v. Dr. PAUL MAYER, Neapel.

In one Vol. Royal 8vo. Price 24s.

ORNITHOLOGY OF ICELAND.
BEITRAG ZUR VOCELWELT ISLANDS.
By B. HANTZSCH. Pg. 347, with 26 Illus. & Map. Price 128.
DIE VÖCEL DER PALÆARKTISCHEN FAUNA.

COLOGNE,
Part III. by E. HARTERT. In 10 parts at 48.

Contains on its more than 900 pages a complete CATALOCUS MAMMALIUM. By E. L. TROUESSART. survey of the apparatus used for instruction in Quinquennale supplementum. 4 Parts. Price 44s.

Physics, as well as numerous practical instrueDO YOU WISH

BEWARE OF

tions and about 3000 illustrations.

FEEBLE
D TO BE

IMITATIONS
UP TO DATE

NATURE says :--" The firm of Leybold Nachfolger in Scientific Demonstrating ? | in Cologne has recently issued a very complete and If so, send for our full descriptive pamphlet of interesting catalogue of physical apparatus and

the Kershaw. Patent Lantern
(Stroud and Rendall's and

fittings sold by them. The book starts with a history
Kershaw Patents), made of of the instruments made in Cologne during the last
best seasoned mahogany,
French polished, lined with

century. In its second section we find an account asbestos and Russian iron. of the construction and fittings of various chemical Fitted with two double achromatic objectives, 90°

and physical institutions. After this follows the catasilvered prism, complete

logue proper, filling some 800 large pages, profusely with B.T. or mixed jet, in travelling case, measuring

illustrated and admirably arranged. The book will be 23" X 16" x 9".

most useful to the teacher." (No. 1846, Vol. 71.) ALL ACCESSORIES SUPPLIED. ARC LAMPS, RESISTANCES,

STANDS, &c. SOLE A. KERSHAW, Dorrington St., Leeds. THE CATALOGUE WILL BE FORWARDED TO SCHOOLS CONTRACTOR TO H.M's GOVERNMENT.

AND INSTITUTES ON APPLICATION.

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THURSDAY, SEPTEMBER 7, 1905.

the steam is given, and an example worked out. The remark is made that “the diagrams so obtained show the characteristics of actual diagrams, but their mean

pressures are naturally much higher than they would MARINE ENGINEERING.

be in actual practice." That is not our experience. Marine Engines and Boilers, their Design and Con.

If the data are rightly used, there is a fairly close struction. Based on the work by Dr. G. Bauer.

approximation between the theoretical and actual Translated from the second German edition by

mean pressures. It is a case in which the precise law E. M. and S. Brvan Donkin. Edited by Leslie S. | of expansion assumed does not very much affect the Robertson. Pp. xxviii + 744. (London: Crosby | result. There is one other small point in this chapter. Lockwood and Son.) Price 25s. net.

The ratio of an actual to a theoretical diagram is

called an “ efficiency” (p. 17). This leads to the THIS considerable work fills a gap in English

awkward statement on p. 35 that “the efficiency of 1 engineering literature. For while the related

triple expansion engines is less than that of single subject of naval architecture has been treated by

cylinder engines." If the more usual term “diagram writers of authority, there is no very good modern

factor” had been used instead of efficiency the statebook on marine engineering. Dr. Bauer states that

ment would be less misleading. it is intended to be a condensed treatise, embodying

Next there is a very short section dealing with some the theoretical and practical rules used in designing

| thermal circumstances affecting the utilisation of marine engines and boilers. But though thus limited

steam. This is too brief to be satisfactory, even from in scope, it treats only of the most modern types and

the point of view of engine design. For instance, the excludes even modern engines and boilers of special

loss due to cylinder condensation is explained by saytypes. As might be expected from the engineer-in

| ing that “heat is withdrawn from the steam at high chief of the Vulcan Works at Stettin, the machinery

pressure and restored to it at a lower pressure" of warships and of some of the great German Atlantic

| (p. 37). The essential point that the heat is chiefly liners are very fully illustrated. There is not a great

restored during exhaust is not mentioned. So the deal of theoretical investigation, but what there is

economy of multiple expansion engines is traced to bears very definitely on design, and is sound so far as

reduction of temperature range. But the re-evaporait goes. Perhaps the most valuable part of the book

tion during exhaust from one cylinder increases the is the great amount of tabulated information about

work in the next. In other respects also the exthe proportions of the machinery in good examples

planation is deficient. However, the thermodynamics of modern practice. There is also a very large collec

of steam engines is fully given in other treatises. An tion of those empirical or semi-empirical rules, based

important section follow's, in which the stroke, speed, on extensive practical experience, on which engineers

and turning moment are discussed. The theory of necessarily so much rely. There is reason to be grate

torsional vibrations is given and practical ful that an engineer so distinguished as Dr. Bauer,

methods of determining the critical speed at with the care of a great factory on his shoulders,

which liability to strong torsional vibrations occurs. should have found time to produce such a systematic

In connection with this there is a brief but clear and treatise, and that he has been able to obtain the

practical treatment of the problem of balancing. Then aid of some of his principal technical assistants in

the arrangement of main engines is explained, and dealing with parts of the subject.

there is a long section dealing with the proportions of The book has been excellently and competently

engine details and including a sufficient account of translated, and the translators have undertaken the

valve diagrams. necessary, but very laborious, task of converting the

Part ii. deals with pumps. Part iii. discusses shaftnumerical statements of formulæ from the metric to

ing, and in connection with this ship resistance, and English measures. However bad our English sys

the proportioning of propellers. German writers are tem of measures may be, English engineers can only

adepts at tabulating coefficients and data, and the think and work in English measures, and the trans

tables in this section are excellent. Part iv. is on lation would have lost very much of its usefulness if |

pipes and connections. Part v. deals with steam the conversion had not been made. Mr. Leslie S.

boilers, and is chiefly descriptive of modern types.

bilers Robertson, who has edited the volume, has had prac- Here again the tabulated data from actual cases is tical experience in this branch of engineering, and has information of the most useful kind, and the rules of already published valuable works relating to it. His

the classification societies, which leave the engineer name is a guarantee that the adaptation of the work

very little discretion, are fully given. The last secfor English readers has been, from the technical pointtion gives some account, rather too much condensed, of view, thoroughly well done.

| of instruments used in steam engine and boiler trials. The general arrangement of the book is convenient. To many readers an account of Fottinger's torsion Part i., which occupies four-tenths of the volume, indicator for measuring the effective horse-power of deals with the main engines. First, indicator engines by observing the torsion of the screw shaft diagrams are discussed, and the application of theo- | will be interesting. Hirn first used a torsion dynaretical diagrams in settling cylinder proportions. The mometer of this kind. As a diagram of the torsion well known method of constructing theoretical angle is obtained, the variation of the power transdiagrams from a diagram of the volumes occupied by mitted can be determined.

No account is given of the most recent change in Special lists are given of the birds of Grimsey and marine engineering, namely, the adoption of the the Westman Islands. Changes in the bird-fauna of steam turbine in place of reciprocating engines. The the whole group of islands, and the general relationsuccess of the steam turbine in this field is already so ships of the fauna form the subjects of two succeed. well assured that a revolution in marine engineering ing chapters, a brief note being appended on domestiis promised. But there are, no doubt, good reasons cated species. for the omission. Experience in the use of steam This completes the introductory portion of the subturbines in ships is almost confined to this country, ject, which occupies ninety-two pages, and the reand naturally at present full information as to the mainder of the text is devoted to the detailed synopsis results, mechanical and economic, of the use of tur of the birds. The total number of species, exclusive bines is only possessed by a few engineers, and is not of the great auk, recorded in the preliminary list as generally available.

definitely known to occur in Iceland is 120, in addition In this country we still rightly pride ourselves on

still rightly pride ourselves on to which are a few of which the right to a place retaining the highest position in shipbuilding and among the fauna is somewhat uncertain. Perhaps marine engineering. But, if we still do more work the most striking feature of the descriptive part of of this kind than any other nation, and if our best the work is the almost painful severity with which work is as good as any in the world, yet Dr. Bauer's new fashions in ornithological nomenclature are book should remind us that in science, experience followed, such appalling alliterations as Merula and skill, other nations now run us very close.

merula merula and Gallina go gallinago gallinago occurring with wearisome frequency. Without reiterating his own private opinion on nomenclature

of this nature, which is now pretty well known, the THE BIRDS OF ICELAND.

reviewer may point out that when the typical form Beitrag zur Kenntnis der Vogelwelt Islands. By B. of a species is alone.recorded, it is perfectly super

Hantzsch. Pp. vi + 341; illustrated. (Berlin : fluous to add the terminal trinomial, Merula merula

Friedländer and Son, 1905.) Price 12 marks. and Gallinago gallinago being in such cases apSINCE Iceland lies on one of the main migration

parently all that can possibly be required. routes, namely, that which starts from Green

Excellent photographs of the eggs, nests, or breedland and Iceland itself, and passes by the Færöes to

ing-haunts of some of the rarer species serve to enliven the British Islands, its bird-fauna is naturally of

the text, and ornithologists will be greatly interested special interest and importance. This is testified by in the two pictures of the eggs and callow young of the appearance within a comparatively short period

| the great skua in their natural surroundings. The of two works on the subject, namely, Mr. H. N. work will doubtless long remain the standard Slater's “ Manual of the Birds of Iceland," published authority on Icelandic birds, at all events for German at Edinburgh in 1901, and the present larger and

readers.

R. L. more pretentious volume. In addition to the general

- ---- - ---- fauna, there is special interest attaching to Iceland as the chief European resort in former days of the

OUR BOOK SHELF. gare-fowl, or great auk. The history of this lost bird

| Neue Fische und Reptilien aus der böhmischen and the literature relating to it the author reserves for

Kreideformation. By Prof. Dr. Anton Fritsch and a supplemental volume. Despite all that has been

Dr. Fr. Bayer. Pp. 34; plates ix. (Prague : Fr. done by travellers and collectors, Mr. Hantzsch is of Rivnac, 1905.) opinion that our knowledge of the bird-fauna of

VERTEBRATE fossils are not only rare, but also badly Iceland is still far from complete, much of the interior

preserved, in the Cretaceous rocks of Bohemia. of the country being difficult of access and still im- Palæontologists must therefore admire the enthusiasm perfectly explored by collectors. Accordingly he is | of Dr. Anton Fritsch, who continues to devote to the fain to admit that the last word on the subject still

ect still | interpretation of difficult fragments so much study as

is evidenced by his numerous writings on these reremains to be said.

mains. In 1878 he published a complete synopsis of The volume commences with an historical survey

| the subject as then understood. Now, with the aid of the growth of our knowledge of Icelandic

of Dr. Franz Bayer in the determination of fishes, ornithology, with notices of the chief explorers and he again publishes an up-to-date treatise, including workers in this field of research, and a list of the | the discoveries of the last quarter of a century. The more important memoirs and books treating of the work is illustrated in Dr. Fritsch's usual style, and a subject. Then comes a detailed account of the

few of the figures are revised drawings of specimens

previously described. author's own journeys in the island for the purpose

Dr. Bayer's chapter on the Cretaceous fishes was of collecting specimens and personally observing the originally published in the Bohemian language in birds. This is followed by an interesting description 1902, but is now made more readily accessible in of the main physical features of Iceland and the German. He describes evidence of several new neighbouring islets, such as Grimsey in the north genera, and species, and concludes that in the

Bohemian Chalk there are more varied representatives and the Westman group in the south, this being illustrated with a number of reproductions of photo- | below the Tertiary formations. In view of the frag.

of the higher fishes than have hitherto been found graphs of the scenery taken by the author himself. mentary nature of most of the fossils, it must be

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