At W. H. DAVISON, M.A., Clerk to the Governing Body. the SOUTH-WESTERN POLYTECHNIC, Manresa Road, Chelsea, S.W., Day College Courses of thirty hours per week will be conducted in preparation for the London University Degrees of B.Sc. in Mechanical and Electrical Engineering, in Chemistry, Physics and the Natural Sciences. The composition fee for the Session of three terms, 1904-1905, is £15. These Courses are recog nised for "Internal Students of the University, and consist of lecture and laboratory instruction. The Courses are conducted by:MECHANICAL ENGINEERING, W. W. F. Pullen and L. D. Coueslant; ELECTRICAL ENGINEERING, A. J. Makower; CHEMISTRY, J. B. Coleman, J. C. Crocker, and F. H. Lowe; MATHEMATICS and PHYSICS, S. Skinner, W. H. Eccles, J. Lister and L. Lownds; BOTANY, H. B. Lacey and T. G. Hill; GEO. LOGY, A. J. Maslen. In the evenings similar Courses will be conducted, but at reduced fees. Also TECHNICAL DAY COURSES of three years' duration have been arranged as a preparation for the Engineering, Electrical and Chemical and Metallurgical professions. The Laboratories and Workshop are open for RESEARCH under the direction of the Principal and the Heads of Departments. Further particulars may be obtained on application to the SECRETARY, who will send either the Day College Prospectus and Calendar or the Evening Class Prospectus for 3d. The Prospectus may be had at the Office for id. UNIVERSITY OF GLASGOW. ADDITIONAL EXAMINERSHIPS. The University Court of the University of Glasgow will shortly proceed to appoint the following Additional Examiners : (a) For Degrees in Arts and Science-ONE EXAMINER in MATHEMATICS. Annual salary, £70. (b) For Degrees in Arts, Science and Medicine-ONE EXAMINER in NATURAL PHILOSOPHY (including Practical Physics). Annual salary, £70. Candidates should be qualified both on the Mathematical and Experimental side. ONE EXAMINER in CHEMISTRY. Annual salary, £50. The appointments will be for three or four years from January 1, 1905, and in addition to the above mentioned salaries, hotel and travelling expenses will be paid. Candidates should lodge twenty copies of their application and testimonials with the undersigned on or before November 12, 1904. ALAN E. CLAPPERTON, Secretary, Glasgow University Court. 91 West Regent Street, Glasgow. SWINEY LECTURES ON GEOLOGY. UNDER THE DIRECTION OF THE TRUSTEES OF THE BRITISH MUSEUM. A Course of Twelve Lectures on "GEOLOGY-THE RECORD AND ITS INTERPRETATION will be delivered by JOHN S. FLETT, M.A., D.Sc., F.R.S.E., in the Lecture Theatre of the Victoria and Albert Museum, South Kensington (by permission of the Board of Education), on Mondays, Wednesdays, and Fridays, at 5 p.m., beginning Monday, November 7, and ending Friday, December 2. Each Lecture will be illustrated by means of Lantern Slides and Lime-light. Admission to the Course free. Entrance from Exhibition Road. By order of the Trustees, E. RAY LANKESTER, Director. British Museum (Natural History), Cromwell Road, London, S. W. UNIVERSITY COLLEGE, LONDON. (UNIVERSITY OF LONDON.) A Course of Eight Lectures on "Current Theories of the Hereditary Process" will be given at Five o'clock on the following Tuesdays:November 22 and 29, December 6 and 13, January 24 and 31, February 7 and 14, by W. F R. WELDON, M.A., D.Sc., F.R.S., Linacre Professor of Comparative Anatomy in the University of Oxford. Syllabuses and Cards of Admission may be obtained gratis by members of the University and of Schools of the University, and on payment of 10s. 6d. by others. WALTER W. SETON, M.A., Acting Secretary. YORK PLACE, BAKER STREET, W. The HALF TERM begins on MONDAY, NOVEMBER 14. The College provides instruction for Students preparing for the University of London Degrees in Arts, Science, and Preliminary Medicine, also instruction in subjects of General Education. There is a Training Department for Teachers, a Hygiene Department, and an Art School. Students can reside in the College. Particulars on application to the PRINCIPAL. BEDFORD COLLEGE FOR WOMEN. (UNIVERSITY OF LONDON.) YORK PLACE, BAKER STREET, W. HEAD OF THE DEPARTMENT: MISS H. ROBERTSON, B.A. Students are admitted to the Training Course in October and January. The Course includes full preparation for the Examinations for the Teaching Diplomas granted by the Universities of London and Cambridge, held annually in December. A Course of Lectures on School Hygiene is held on Saturday mornings. Full particulars on application to Miss ROBERTSON. BEDFORD COLLEGE FOR WOMEN. (UNIVERSITY OF LONDON.) YORK PLACE, BAKER STREET, W. The Council are about to appoint a Lady as HEAD of the TRAINING DEPARTMENT. Applications must be sent by November 25 to the SECRETARY of the College, from whom further information may be obtained. H. WALTON, Secretary. COACHING (THEORY AND PRACTICE) In BIOLOGY, BOTANY, CHEMISTRY and PHYSIOLOGY for MEDICAL EXAMS. Especial Course of Instruction in THERAPEUTICS, PHARMACOLOGY and MICROSCOPY for INSTITUTE OF CHEMISTRY EXAM. Mr. FREDERICK DAVIS, The Laboratories, (Registered in Column B (Advanced Education), Teachers Registration Council, Board of Education, S.W.), 49 and 51 IMPERIAL BUIldings, Ludgate circus, e.c. TO SCIENCE AND MATHEMATICAL MASTERS.-January (1905) 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 will be sent. Wanted for Protestant Irish School after the Christmas holidays, a Master to teach Modern Languages and Auxiliary Subjects. An Englishman who has resided abroad preferred. Salary, 150 per annum; non-resident. Also a Science Master with Certificates for the teaching of Drawing. Salary, 150 per annum; non-resident. Applications, with copies of Testimonials and Photos if possible, to be sent to HEAD MASTER, Office of this paper. SCIENCE & MATHL. APPTS.-(1) Public Sch., Nat. Sc. and Drawg., £150 + fees; valuable post to good man. (2) Chem. and Physics-little English. Games preferred. £120, res. (3) Chem.+ Magnetism and Electricity. £100, res. Many January Appts. Messrs. NEEDES & SELLICKS, Scholastic Agents, Clock House, Arundel Street, Strand. MANSFIELD. An ASSISTANT MASTER is required to teach Woodwork and Lower Form Subjects. Salary, £95 per annum Apply, stating age, qualifications and experience, with names of three references, to C. E. STACEY, B.A., B.Sc., Head Master. THE VERDIN TECHNICAL SCHOOL. SECONDARY DAY SCHOOL. The Winsford Higher Education Committee invite applications for the post of ASSISTANT MASTER in the above Secondary Day School, at a commencing salary of £120 per annum. Special qualification, Chemistry; but applicants must be able to give instruction in English subjects (or other available subjects of the School Curriculum). The Master appointed will further be required to teach Chemistry on two evenings per week during the winter months in the Evening Technical School, and will be expected to take part in the School Games (Hockey and Cricket). Applications, endorsed "Assistant Master," stating age, accompanied by copies of not more than three testimonials, should be delivered to the HEADMASTER, Verdin Technical Schools, Winsford, Cheshire, not later than Monday, November 14. Winsford, Cheshire, November 1, 1904. JNO. H. COOKE, Clerk to the Committee. J. N. BIRCH, B.A., Principal. CITY OF BIRMINGHAM. MUNICIPAL TECHNICAL SCHOOL. The services of a LECTURER in ELECTRICITY and PHYSICS are required in January next. The commencing salary offered is £140. The last date for sending in applications is November 19 next. Full particulars of the post will be forwarded on application to Offices of the School, Suffolk Street October 17, 1904. OWEN'S SCHOOL, ISLINGTON. WANTED in January, PHYSICS MASTER and CHEMISTRY MASTER. Must have had experience in good laboratories, and be able to lecture and illustrate by experiments in an efficient manner. There are two Science Masters on each side. Commencing salary, £150. Apply at once, giving age, qualification, experience, and copies of three recent testimonials, to the HEAD MASTER. JOHN BROWNING, Optician, 78 STRAND, LONDON. SANGER-SHEPHERD NEW PATTERN AUTOMATIC ARC-LAMP FOR LABORATORY WORK. 125 Candle Power. A low power Lamp, invaluable as white light illuminant for Microscopic, Spectroscopic, and Photographic Work. SPECIFICATION. - Automatic Arc Lamp in nickel-plated ventilated cover, suspended on adjustable stand with self-contained resistance, fine centreing adjustment by screwed nut suspension. As open or closed arc, requires only 14 amperes on 100/110 volt direct current circuit. Complete with flexible cord and plug, for instant attachment to ordinary bayonet lamp socket. Burns 20 hours without attention. With Stand (as shown), £4 10 0 Lamp only, £2:15 : 0 Also supplied for 200 volts. SANGER-SHEPHERD & CO., 5, 6 & 7, Gray's Inn Passage, Red Lion St., Holborn, London, W.C. THE BECQUEREL RAYS AND THE PROPERTIES OF RADIUM. Demy 8vo. With Diagrams. 8s. 6d. net. AN INTRODUCTION TO THE THEORY OF OPTICS. Lecturer on Forestry, Durham College of Science. THE ELECTRIC FURNACE. Professor of Chemistry at the Sorbonne. Translated by A. T. de MOUILPIED, M.Sc., Ph.D. Demy 8vo. With numerous Illustrations. IOS. 6d. net. London: EDWARD ARNOLD, 41 & 43 Maddox Street, W. REYNOLDS & BRANSON, LTD., Scientific Instrument Makers to the Indian Government and Science and Art Department. LABORATORY FURNISHERS AND MANUFACTURING CHEMISTS. NEW PHOTOGRAPHIC DARK ROOM LAMP THE "RYSTOS" ELECTRIC (No. 1) LAMP For Standing or Hanging, with Cord and Dimensions, 4 in. x 8 in. LAMPS FOR GAS ALSO WITH BYE-PASS. SCOTTISH PROVIDENT IN this SOCIETY are combined the ADVANTAGES of The Premiums are so moderate that at most ages an Assurance of £1,200 or £1,250 may generally be secured from the first for the same yearly payment which would elsewhere assure (with profits) £1,000 only. The Whole Surplus goes to the Policyholders on a system at once safe and equitable, no share being given to those by whose early death there is a loss. Surplus at last Investigation, £1,581,000. Over 60 per cent. of the Members who died during last Septennium were entitled to Bonuses which, notwithstanding that the Premiums do not as a rule exceed the profit rates of other Offices, were, on the average, equal to an addition of over 50 per cent. to the Original Assurances. non ENDOWMENT ASSURANCE-WITH BONUS -SPECIAL CLASS. PROSPECTUSES, with full information, may be had on application. Accumulated Funds exceed £13,000,000. HEAD OFFICE: 6 ST. ANDREW SQUARE, EDINBURGH. LONDON OFFICE: 17 KING WILLIAM STREET, E. C. WEST END BRANCH: 17 PALL MALL, S.W. 1984 NATURE A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. Of Nature trusts the mind which builds for aye."-WORDSWORTH. THURSDAY, NOVEMBER 3, 1904. APPLIED ELECTRICITY. (1) Wireless Telegraphy. By C. H. Sewall. Pp. 229. (London: Crosby Lockwood and Son, 1903.) Price IOS. 6d. net. By (2) Electricity in Agriculture and Horticulture. By F. Price (7) L'Année Technique (1902-1903). By A. Da Cunha. Pp. 303. (Paris: Librairie Gauthier-Villars, 1903.) Price 3.50 francs. (1) A2 LTHOUGH wireless telegraphy is of such recent development, it is apparently regarded by many as a legitimate subject for historical writing. The first volume before us is one of several which have appeared in the last three or four years in which the historical progress of wireless telegraphy is dealt with rather than its scientific principles. The book possesses to our mind the same faults which characterise all the other similar publications which we have read; there is a lack of discrimination in the selection of material which is likely to leave the untechnical reader in a state of considerable confusion. Wireless telegraphy as we know it to-day is wholly concerned with Hertzian wave telegraphy, and even if accounts of the experiments of Lindsay and others in telegraphy by earth or water conduction should be regarded as legitimate, we cannot see by what possible stretch of the imagination the achievements of, say, Marconi can be traced back to the prophecies of Galileo in 1632. Mr. Sewall's method of compiling history appears to consist chiefly in making extracts from patents. Page after page of the book before us contains nothing more than reprints from the patents of Lodge, Marconi, Fessenden, and others, sometimes verbatim in inverted commas, at others with slightly altered context as original matter. We imagine it must be easier to write books in this way than it is interesting to read them. Mr. Sewall would have been much better advised, we think, to digest his material properly and present it to his readers in some more acceptable form. He could then have given a connected account of the remarkable developments that have followed the discoveries of Maxwell and Hertz which would have been of great practical use to students of the subject. At present we doubt if his book is intelligible to the amateur or useful to the expert. (2) The late Prof. S. Lemström occupied himself for many years with experiments on the effect of electricity on growing plants, and this little book contains the results of his work. If the conclusions at which the author arrives are confirmed by the work of other incareful consideration by all agriculturists. Practically vestigators, the subject is one which merits the most only one type of experiment was tried; an influence machine was connected with one pole to earth and the other to a wire network over a field in which the crops were being grown. A discharge current could thus be passed either from the network to earth or vice versâ for any desired number of hours a day. The experiments were tried on a comparatively large scale in several different localities. The effect produced by this treatment was remarkable. There was an average excess of the crop of the experimental field over that of a control field of 45 per cent.; the excess varies considerably with the nature of the crop and the conditions, soil, weather, &c. Not only is this increase in quantity produced, but there is also often an improvement in quality and a diminution in the time taken for the plants to mature. This last is a factor often of great importance to the grower, who can realise much higher prices by selling early in the season. Prof. Lemström calculated that in the case of wheat the outlay on a field of 25 acres will be repaid in two or three years, and that afterwards a net profit of 40l. a year or more can be realised. We cannot here enter into the details of the working, such as the best time of electrification, the effect of wet and dry weather, and so forth, but we should strongly advise those interested in the subject to study this book carefully; they will find it full of valuable suggestions, and the time spent in reading it will be amply repaid. (3) We have already reviewed the first three volumes of this publication, so that it is only necessary here to refer briefly to the matter contained in the present volume. This is devoted to electric tramways, and is divided into seven chapters, dealing with overhead construction, feeders, surface contact systems, conduit systems, rolling stock, electric boats and motor cars, and electric traction on railways. The defects to which we alluded in our previous review are not so noticeable in this volume, which furnishes a good description of a very important branch of electrical engineering. The excellence of the illustrations is a characteristic of the whole production, and is a particularly valuable feature in the present instance, as the subjects are such that they cannot be effectually described without numerous photographs and diagrams. (4) This exceedingly interesting monograph on the much debated theory of the chemical reactions taking place in the lead accumulator is probably already well known in the original German to those who have concerned themselves specially with this subject. Since the book first appeared the discussion has progressed a stage further, so that the English translation may be said to be out of date to a certain extent. This is, however, the penalty that the average English student has to pay for the neglect of his schoolmasters to teach him German, and he will probably therefore welcome the appearance of an English translation. Herr Dolezalek treats the subject from the standpoint of Nernst's osmotic theory, and shows that thermochemical considerations all point to the validity of the sulphate theory originally advanced by Gladstone and Tribe. Whether the author will succeed in satisfying others to the same extent as he has apparently satisfied himself may be regarded as open to question, but in any case the book is one which cannot be neglected by anyone wishing to study this complicated but fascinating problem. The book is divided into two parts, the first dealing with continuous and the second with alternating current motors. The relative advantages of different types are considered in detail, and there are numerous calculations of motors of different types and capacities. In addition, there are a large number of curves, diagrams, and photographs. (6) The essays which are comprised in M. Cornu's little book were written with a special and rather peculiar object, the author having been requested by some of his old pupils, who had been unable to keep touch with the rapid development of electrical engineering, to write for them something which would enable them to appreciate better the technical or semi-technical literature of to-day. These "Notices" are consequently of a somewhat elementary character, nor can the book be regarded in any sense as a text-book of electricity. But M. Cornu has succeeded in writing a book which should appeal to a very much larger audience than that for which it was originally intended; one cannot look through its pages without realising at every point that it is the work of a master, and such works repay study by all-the most advanced as well as the most elementary students. The beginner will find here ideas expressed clearly and concisely, and cannot fail to derive great benefit from the book as an introduction to more detailed treatises. The engineer will see well known facts expressed in new and suggestive language, and will doubtless have his own views enlarged in consequence. The subjects dealt with are the correlation of the phenomena of static and dynamic electricity, generators, transmission of power and polyphase currents, and we would strongly recommend anyone interested in any of these matters to spend a few hours reading M. Cornu's admirable booklet. (7) We cannot help being conscious that the end of 1904 is rather late in the day to review a book which contains a résumé of the technical achievements of 1903. Still, as we gather that this publication is intended to appear annually, this notice may be of some service in directing readers' attention to the volume dealing with this year's progress, which we imagine will appear very soon; in addition, it may be pleaded that the lapse of time enables one to see matters more in the right perspective, and so to form a better estimate of the value of M. Da Cunha's work. The book ranges over a great variety of subjects. Thus we find at one place a mathematical calculation of the (5) The design and construction of electric motors mechanical problems involved in "looping the loop," is becoming daily a matter of more importance to and in another a discussion of alcoholism and temperelectrical engineers on account of the very rapid ance worthy of the columns of a daily paper in the extension of the use of electricity for power purposes. silly season. Between these extremes lie such subjects. When one considers the enormous number of tramcars, as the progress in wireless telegraphy, automobilism. lifts, factories, &c., which are driven by electricity, it aërial navigation, and the hundred and one other is easy to see not only how important the subject is, but technical developments which are taking place in all also how very varied is the work which the electric branches of applied science. To the engineer the book motor is called upon to perform. If the development can serve no other purpose than to while away an idle now is great, in a few years' time, when some of the hour or so. The general reader who is interested in numerous power schemes are more matured, it will be scientific and technical progress may read it with both much greater still. The student of electrical engineer-profit and pleasure. He will find the descriptions clear, ing may find here ample scope for his abilities, and he the style agreeable, and the illustrations and diagrams cannot consult a better guide than the volume before us. in many cases excellent. M. S. |