COUNTY BOROUGH of SUNDERLAND THE TECHNICAL COLLEGE, SUNDERLAND. Owing to the appointment of the present holders to Lectureships at the Manchester School of Technology. the Governors invite applications for the posts of SENIOR and JUNIOR ASSISTANT. The standard is that of a University College, and applicants for either post should be able to give instruction of that character. A special knowledge of laboratory work is desirable for the senior post, and of drawing office practice for the junior. Applications to be sent in not later than October 16. Education Department, 15 John Street, Sunderland, October 3, 1905. T. W. BRYERS, Secretary. (IN THE UNIVERSITY OF DURHAM.) The Council will shortly appoint a LECTURER in APPLIED MATHEMATICS. Salary to commence at £200 per annum. The Lecturer will be required to assist in the general teaching work of the Mathematical Department. Candidates should send three copies of their application and testimonials to the undersigned, on or before November 1, 1905. F. H. PRUEN, Secretary. Armstrong College, Newcastle-upon-Tyne. BRISTOL EDUCATION COMMITTEE. FAIRFIELD SECONDARY SCHOOL. WANTED, experienced FIRST LADY ASSISTANT, who must be graduate or hold equivalent Diploma, qualified in Mathematics, Hygiene, and ordinary Form subjects. Among other duties she will be required to supervise under the Principal all the girls, to organise school games, &c. Salary, 120, rising by annual increments of £5 to £140 per annum. Application forms, which may be obtained of the SECRETARY, must be received not later than October 25. Education Offices, Guildhall, Bristol. ROYAL AGRICULTURAL COLLEGE, CHAIR OF MATHEMATICS AND PHYSICS. The Governing Body invite applications for the above, vacant at Christmas next. Emoluments: Fixed Stipend of £150 per annum; Capitation Fees of about £35 per annum; board and rooms in the College during Session. Applications, with statement of qualifications, age, degree, testimonials, &c., to he addressed to the PRINCIPAL. SCIENCE MISTRESS wanted immediately for Girls' School near London. Botany, Chemistry, Physics, B.Sc. or equivalent essential. £100 to £120, non-resident. Experience necessary. Address GRIFFITHS, SMITH, POWELL & SMITH, Educational Agents, 34 Bedford Street, Strand, London. TO SCIENCE AND MATHEMATICAL MASTERS.-January (1906) Vacancies.-Graduates and other well qualified Masters seeking posts in Public and other Schools for next term should apply at once, giving full details as to qualifications, &c., to Messrs. GRIFFITHS, SMITH, POWELL & SMITH, Tutorial Agents (Estd. 1833), 34 Bedford Street, Strand, London. Immediate notice of all the best vacancies for Science and Mathl. Masters will be sent. Binocular Microscope, full size, by Smith and Beck, Universal action, mechanical stage, revolving selinite stage, 7 eye-pieces, 6 finest objectives, 2, 1, 1, 1, 1, in., magnifies 25 to 8000 times, achromatic, bull's-eye, and parabolic condensers, revolving nose-piece, diaphragms, silver side reflector frog stage, nicol prism, camera lucida, tourmaline lens, polariscope, draw tube, forceps, slides, live boxes, &c. Cost £80; bargain, 28 Gns. Approval; Deposit. -TABOR, 6 Monument Street, E.C. FOR SALE.-18-inch Spark Induction Coil, Newton Apps, in perfect condition; also several 10-inch Spark Coils, Newton-Apps, and others, jet breaks and accessories.-G. BOWRON, 57 Edgware Road, London, W. FOR SALE.-Chemical Society Journal, 1876 to date, also Berichte, 1894 to date; both well bound and complete.-Apply "McK.," Birkbeck College, E.C. Sale by Auction. THE CONTENTS OF THE OBSERVATORY AT TUESDAY, OCTOBER 17, AT 12.30. MR. J. C. STEVENS has received instruc tions from the Executors of the late Dr. Isaac Roberts to Sell by Auction, on the premises as above, the contents of the Observatory, comprising a 20-inch Photo Reflecting Telescope with two mirrors Two Astro. Stellar Cameras; a 7-inch Object Glass, Cooke Refractor; the Equatorial Stand, with Driving Clock, by Grubb; Transit Instru ment; Sidereal Clock, by Palmer; Micrometers; Two-day Ship Chronometer, by Farquhar; Spectroscopes; Lathe and Tools, and other important effects. May be viewed week prior from ten to four, and morning of sale. Catalogues and all particulars on application to Mr. J. C. Stevens, 38 King Street. Covent Garden, London, W.C. TABLE OF RARE ELEMENTS. By E. L. N. ARMBRECHT. WANTED, a gentleman who has good Symbols, Atomic Weight, Discoverer, Isolater, Specific Gravity, Principal knowledge of the Microscope and Microscopical Apparatus combined, with commercial ability to represent Manufacturers of these goods having a world-wide reputation. His services would be required to introduce the above to Hospitals, and to demonstrate before Societies. -Address Box 1876, c/o NATURE. Source, Melting Point, Properties, Salts of, Price, &c. ARMBRECHT, NELSON & CO., 71 & 73 Duke Street, Grosvenor Square, W. N.B.-Sent Free on application. LANTERN SLIDES of Scientific Subjects, Also Hand Painted from 1/3 to 5/- each. Slides from Prints, Drawings, Photographs, &c,, a Speciality. PHOTOMICROGRAPHS. Storage Cabinets for Lantern Slides to hold 400, 10/6; 600, 14/6; 1200, 25/6. See List. MICROSCOPICAL SLIDES, Botanical, Zoological, &c., from 6s. per dozen. FLATTERS & GARNETT, Ltd., 48 DEANSGATE, And at CHURCH ROAD, LONGSIGHT, MANCHESTER. Accurate and THE NEW PATENT PRICE 21/ THE DECIMAL ASSOCIATION. Office for all Publications: 605 SALISBURY HOUSE, LONDON WALL, E.C. An explanatory chart of the metric system can now be obtained on application to the Secretary at the above address, price 1/-. Or it can be supplied, mounted on linen, fitted with rollers and varnished, for 5/-. Postage is included in both cases. The chart measures 112 centimetres X 61 centimetres (44 ins. x 24 ins.) The chart was compiled by Mr. J. G. Pilter, of Paris (a member of the Executive Committee), and bears the written approval of Lords Kelvin, Belhaven and Stenton, Avebury, Spencer, and Tweedmouth, Right Hon. H. O. Arnold-Forster, Sir J. T. Brunner, Sir Wm. Huggins, Sir Oliver Lodge, Sir Wm. Mather, Sir G. L. Molesworth, Sir W. H. Preece, Sir. Wm. Ramsay, Sir Henry Roscoe, Mr. Alex. Siemens, Dr. Selwyn, Dr. Gray, Sir Samuel Montagu and Mr. Dowson; of the Chairman and some of the Members of the Select Committee of the House of Commons of 1895; and of the President and ExPresident of the Associated Chambers of Commerce PIESMIC BAROMETER. for the year 1897. All the signatures are reproduced in fac-simile, which adds greatly to the interest or the chart. To be obtained of all Opticians, or CLERKENWELL OPTICAL WORKS, 142 ST. JOHN STREET, LONDON, DENT'S CLOCKS, E.C. SECOND-HAND TELESCOPES. 4-in. Cooke Equatorial, with extra Altazimuth Mount, £60. 4-in. Wray, Slow Motions complete, £30. 4-in. Wray Ordinary, £25. 84-in. Browning Reflector, £15. 6-in. Calver Reflector, £12. 6-in. Calver Equatorial, £15. 3-in. Student Steward, £4 10s. 3-in. Student Solomon, £2 15s. and £3 10s. SECOND-HAND MICROSCOPES. Watson's Edinburgh Student, complete with fittings, £15. Swift's Bacteriological, £15. Beck's "London," complete, £8 10s. Microscopes from 20s. upwards to suit all students. Many others, all kinds. Lists on Application. CLARKSON & CO., A. 28 BARTLETT'S BUILDINGS, HOLBORN CIRCUS, LONDON. INVAR The Alloy of Nickel Steel which has an extremely BASE-LINE MEASURING APPARATUS, PENDULUMS, BALANCES J. H. AGAR BAUGH, 92 Hatton Garden, London, E.C. Telegrams: "VOIDER, LONDON." HARVEY & PEAK, BY APPOINTMENT TO THE ROYAL INSTITU. POST OFFICE BRIDGE SETS AND ELECTROMETER, NEW PATTERN. A NEW PATTERN FORTIN'S STANDARD BAROMETER (Registered Design No. 420,297.) As will be seen by the illustration, this Barometer is built on original lines. By the absence of the ordinary tubular enclosures (in the usual form of instrument) the mercurial column is FULLY EXPOSED to view, NO SHADOWS are thrown upos the column, and therefore an extremely accurate and in stantaneous reading is made possible. The scales being graduated upon the flat side pieces the DIVISIONS AND FIGURES ARE ALWAYS IN VIEW, and the vernier is very much more legible than in the ordinary tubular patterns. The bore of the tube is 0.5 inch. The scales are graduated in inches and millimetres, and, by means of the verniers, are capable of being sub-divided to read to 0.002 inches and 0°1 m/m. The attached Thermometer on the body of the instru ment is graduated in Fahrenheit and Centigrade scales. It is the BOLDEST Standard Barometer made. The PRICE IS LOWER than that of any other form of Standard Barometer of the same dimensions. It yields readings equally close as the highest priced instruments. Price complete, mounted on handsome Polished Solid Mahogany Board, with Brackets for Suspension, and Opal Glass Reflectors, £7 10s. Od. SMALLER SIZE, "THE STUDENTS," designed for Schools for demonstration work, and small private Observatories; bore '25; reading to 01 Inch and 1 millimetre. £3 7s. 6d. Sole Manufacturers and Proprietors of the Regd. Design N. B. If any difficulty be found in securing any of our Instru ments through your Dealer, kindly communicate with us. CHARLES GRIFFIN & CO., Ltd.'s, W. H. SMITH & SON'S NEW BOOKS AND NEW EDITIONS. JUST OUT. FULLY ILLUSTRATED. 6s. net. TESTING EXPLOSIVES. By C. E. BICHEL and AXEL LARSEN. CONTENTS.-Historical-Testing Stations-Power Gauges-Products of Combustion-Heat of Decomposition-Rate of Detonation-Rate and Duration of Flame-After Flame Ratio-Transmission of Explosion-Efficiency. JUST OUT. VOL. I. FIFTH EDITION. REVISED. 8s. 6d. APPLIED MECHANICS, AND MECHANICAL ENGINEERING. By ANDREW JAMIESON, M. Inst. C. E., M.I.E. E., F.R.S.E. In Two Parts. Part I.-The Principle of Werk and its Applications. Part II.-Friction, Gearing, &c. "Fully maintains the reputation of the author."-Pract. Engr. SIXTH EDITION. REVISED. FULLY ILLUSTRATED. 38. 6d. MAGNETISM & ELECTRICITY. By ANDREW JAMIESON, M.Inst.C.E., M.I.E.E. "A thoroughly trustworthy text-book. Practical and clear."-Nature. NOW READY. THIRD EDITION. REVISED. IN HANDSOME CLOTH. ILLUSTRATED. 10s. Ed. PROPERTIES OF MATTER. Being Volume I. of A TEXT-BOOK OF PHYSICS. By J. H. POYNTING, Sc.D., F.R.S., Professor of Physics, Birmingham University, and J. J. THOMSON, M.A., F.R.S., Fellow of Trinity College, Cambridge; Professor of Experimental Physics in the University of Cambridge. "We regard this book as quite indispensable not merely to teachers, but to physicists of every grade above the lowest."-University Correspondent. LIBRARY EMBRACES ALL THE MOST IMPORTANT BOOKS, BIOGRAPHIES AND MEMOIRS, TRAVEL AND SPORT, HISTORY, THEOLOGY; SCIENCE AND SOCIOLOGY, NATURAL HISTORY, LITERATURE AND ART, POETRY AND ESSAYS, TOPOGRAPHY, FICTION, REVIEWS, AND MISCELLANEOUS WORKS. The newest and best books of popular interest are added as published. The books are delivered to the Bookstalls to Sub scribers' orders, carriage paid. Over 800 branches to which Subscribers can be trans. ferred. Special Travelling Subscriptions entitling Members to exchange at any branch without previous notice. Term on application. Books exchanged by Parcels Post, Rail, or other means from the Head Office to any part of the United Kingdom. Boxes supplied gratis. Prospectus and list of recent books in circulation and any other information can be obtained upon applicaties A catalogue of Surplus Library and New Remainder Books, offered at greatly reduced prices is published monthly, and supplied gratis on application HEAD. 186 STRAND, LONDON, W.C. OFFICE: THURSDAY, OCTOBER 12, 1905. TWO RECENT VOLUMES ON ARACHNIDA. On Two Orders of Arachnida. Opiliones, especially the Suborder Cyphophthalmi, and Ricinulei, namely, the Family Cryptostemmatoidae. By Dr. H. J. Hansen and Dr. W. Sörensen. Pp. 1-182; 9 plates. (Published by aid of a subsidy from the Royal Society of London, Cambridge, 1904.) Price 158. net. Palaeozoische Arachniden. By Prof. Dr. Anton Fritsch. Pp. 1-80; 5 plates and many text figures. (Prag: Selbstverlag. in comm. bei Fr. Řivnáč, 1904.) ARACHNOLOGISTS must unite in a vote of thanks to Drs. Hansen and Sörensen for their splendid achievement in producing their treatise on Arachnida. The volume, announced many years ago as in preparation, is based upon a wealth of material borrowed from every available source such as no other taxonomists have been able to examine. It is a monument of careful research, and in every way worthy of the high reputation of its authors. Though written in a foreign tongue, the letterpress contains no passage of doubtful meaning; and Hansen's inimitable drawings have received full justice from the lithographic skill of Wilson at Cambridge. The Royal Society was well advised in contributing to the cost of publication. The first and most valuable part of the book deals with the Opiliones, a highly specialised order the morphology of which has baffled previous workers. By the comparative and careful study of a host of forms, the Danish authors have succeeded in explaining the complicated structure of the genital area, or at all events in offering an explanation which will probably stand unless ultimately disproved by embryology. They have accepted the opinions of Simon and Thorell as to the division of the order into three suborders, and supplied diagnoses of the families of the Palpatores. In the case of the Cyphophthalmi, the least known of the suborders, a complete monograph of all the species is given, together with some new anatomical details, including the important discovery that the so-called ocular tubercles bear, not eyes, but the orifices of Krohn's glands. Incidentally, Stecker's monster, Gibbocellum, is disposed of, and, it is safe to say, will never again figure in literature. Exact and admirable, however, as the work is, it must not be regarded as above criticism; nor must all the statements be accepted with a childlike faith. Far from it. The limitations of the authors are well known and are sufficiently in evidence in this volume, more especially in the pages dealing with the Micrura. For example, Börner's view that the "labia" in Arachnida are not homologous sclerites is worth far more than the unreasoned dismissal it receives; and it is not very obvious why the first abdominal sternal plate in the Ricinulei is homologised with the pregenital rather than with the genital sternite of the Pedipalpi. Exception also must be taken to the application of the term 66 antenna to the appendages of the first pair, and of "mandibles" to the basal segment of those of the second pair, in the Arachnida. The first change is defensible only on the grounds that the cheliceræ of the Arachnida are the homologues of the antennæ of insects and of the antennæ of the first pair in crustaceans. Those who adopt this terminology, however, must consistently apply the term 66 99 antenna to the buccal gnathites of Peripatus. Again, the name "mandible" is presumably given to the basal segment of the appendages of the second pair because of its supposed homological correspondence to the "mandible" of the insects or crustaceans an opinion not generally accepted. Points of this kind, however, would scarcely be worth mentioning were it not for the apparent inclination on the part of the authors to forget the possibility of two or more views being held on matters about which embryology is, up to the present, silent. As a last word of praise, may we, in all sincerity, congratulate the authors on the considerate tone of their criticisms and on the general absence of that air of self-satisfied arrogance for which certain Danish publications on Arthropoda have gained an unenviable notoriety? It is to be hoped that the English supervision of the letterpress is not in any way responsible for this improvement. Dr. Fritsch's monograph of the Palæozoic Arachnida is a volume of a quite different character. Plainly speaking, it is an anachronism reminiscent of the dark days of palæontology when that science was held to be independent of neontology, or at all events independent in the sense that an acquaintance with the structure of the living species of a group was regarded as superfluous for the correct determination and description of its fossil forms. The comparative morphology of recent Arachnida, even with well-preserved material for examination, is difficult enough. Was it likely, then, that any great measure of success would attend the efforts to interpret the elusive structural points of Carboniferous fossils of a palæontologist unguided by scientific familiarity with recent forms? But, although want of the requisite knowledge is plainly attested and shatters all con The second part deals with an order of peculiar interest, the Ricinulei or Podogona, which has existed unchanged from Carboniferous to modern times. Amongst the anatomical discoveries made by Hansen and Sörensen, two stand out as of the greatest interest, namely, the presence of a pair of tracheal respiratory organs in the prosoma and of the elements of nine somites in the opisthosoma. The association of this order with the Pedipalpi, Araneæ, and Palpi-fidence in the alleged observations and attempted gradi is of interest, even if the reasons for it are unconvincing; but surely greater prominence should have been given to the fact that Börner anticipated the Danish authors in this matter! restorations, yet without examination of the specimens themselves no one has the right to affirm positively that a statement is false or a drawing inaccurate in any given particular. However strongly |