Jamcaby 1, 1900.] 



KNOWLEDGE 



17 



by the City Corporation, and a site at South Kensing- 

 ton had alreadv been promised for a new science college 

 and museum, but. at last, Sir William Harcourt, 

 in 1892. then Chancellor of the Exchequer, offered the 

 site at Millbank. Th? Tate Gallery was opened 21st 

 July, 1897, and so recently a-s i27th November, 1899, 

 the opening of a new wing completed the great building 

 which British Art owes to Sir Henry Tate's munifi- 

 cence. 



Sftrncf i^otr. 



Royal Institution. — The following arc the Lecture 

 Arrangements at the Royal Institution before Easter ; — 

 Mr. C. Vernon Boys, Six Christmas Lectures (especially 

 adapted for voung people) on Fluids in Motion and at 

 Rest; Professor E. Ray Lankester, Twelve Lectures on 

 The Structure and Classification of Fishes; Dr. 

 W. H. R. Rivers, Three Lectures on the Senses of 

 Primitive Man; Professor H. H. Turner, Three Lec- 

 tures on Modern Astronomy; Dr. Charles Waldstein, 

 Three Lectures on Recent Excavations at Argivc 

 Heraeum (in Greece); Three Lectures by Sir Hubert H. 

 Parry; Mr. W. L. Courtney. Three Lectures on The 

 Idea of Tragedy in Ancient and Modern Drama ; 

 The Right Hon. Lord Rayleigh, Six Lectures on Polar- 

 ised Light. 



♦ 



i^ottcts of Boolts. 



Handbuch der Aatronomhclif Inxlrumentenkunde. A descri])- 

 tion of the instruments used in astronomical observations, 

 together with an explanation of their construction, their appli- 

 cation, and their mounting, on fundamental principles. By 

 Dr. L. Ambronn. Two volumes, containing 118.0 figures in 

 the text. (Berlin : Juhns Springer. 1899.) Dr. Ambronn has 

 produced a work which is unique of its kind, and which will, 

 beyond doubt, be regarded as classic. From time to time our 

 great instrument makers in England have published catalogues 

 of their telescopes and mountings, and perhaps a full description 

 of their properties and the methods of making and adjusting 

 them, but these cannot for a moment compare with the ency- 

 clopaedia of instruments and instrumental adjuncts that has just 

 been compiled by Dr. L. Ambronn. In Germany, Carl wrote, 

 about 1860, his '" Principien der Astronomi^ehen Instrumenten- 

 kunde," and, twenty years later, Yon Konkoly hi.s " Anleitung 

 zur Ansf iihrung Astronomischer Beobachtungen " ; and, quite 

 lately. Professor E. Becker has produced a monogra])h on the 

 " Mikrometer " ; but these may be regarded as simplj' intro- 

 ductory to Dr. Ambronn's work. The two volumes contain 

 together some 1276 pages, and are divided into seven chapters. 

 The first chapter treats of the adjuncts of an astronomical 

 instrument — screws of all sorts, both for clamping, for correct- 

 ing and motion, and for measuring ; i)lummets and levels ; 

 artificial horizons, collimators and verniers, and reading micro- 

 scopes. All these are very copiously illustrated ; and Dr. 

 Ambronn has not confined himself to a mere description of 

 them by word or woodcut, h\it discusses their properties, their 

 errors, and the necessary corrections for these, whether by 

 mathematical or by instrumental means. The second chapter 

 takes up the question of the recording and noting of time, 

 whether by clock or chronometer, by pendulum, hairspring, or 

 electric control ; the regulation of motion and compensation. 

 Chapter three is divided between three large subjects. The 

 first has to do with the axes of a telescope, and the supports on 

 which they rest or in which they turn. The second division 

 takes the two great forms of instrument with which telescopic 

 work may be done — the refractor and the reflector. In the case 

 of refractors, there is a verj- full description of the manner of 

 choosing the glass, the grinding and figuring of the lenses, and 

 methods of combining the lenses of different glass and different 

 form to make the finished objective. The mounting of the 

 objective in its cell is not omitted, nor the effect of the whole 

 on the form of the stellar image. The methods of figuring and 



polishing, or silvering the mirroi-s, and the different forms of 

 refiecting telescopes, are fully described. The tliird division 

 tolls of the constructing and dividing of the circles and of the 

 determination of their errors, and several pages are devoted to 

 cl imps and slow motions. Tlio fourth chapter, of 120 pages, 

 takes the micrometer in all its forms, from the simplest focal 

 micrometer to the great RadcIifTi; and Repsold heliomcters. 

 It is a very great gain that these important instruments are so 

 fully figured. The next two chapters — comprising nearly the 

 whole of the large second volume — consist of descriptions of 

 the important instruments of the world, which arc remarkable 

 for their size and ])Owlt, or for their perfect or ingenious form 

 of mounting, or for their adaptation to .some particular object. 

 We find here the photometers of the Harvard Observatory, of 

 Stoinheil, Knobel, and Pritchard ; the measuring apparatus of 

 Kaptoyn ; the meteor camera of Elkin ; the great refractors of 

 Yerkes and Lick ; the elbow form of mount in use at Potsdam ; 

 tlie twin telescopes of Greenwich ; the great reflector of Dr. 

 Isaac Roberts. Incidentally, Dr. Ambronn mentions that the 

 chief reflectors are made and used in England, the exceptions 

 being tho.se of ProfessorSafarik, at Prague, and of the well-known 

 optician, Dr. H. Schrcider. The final cliapter is devoted to tlie 

 housing of the telescopes. Pretty nearly every sort and shape 

 of dome is figured and described. The omissions are very few 

 and slight. We are sorry not to see any description of tlie 

 ]iroperties, or use for astronomical purposes, that the portrait 

 lens has been put to by Professor E. E. Barnard and others. 

 There are, also, one or two special forms of photographic 

 objectives which apparently are not described — notably a very 

 short focus portrait lens by Voigtlander and Sohn, and Mr. J. H. 

 Dallmeyer's stigmatic lens. Perhaps the section which is the 

 least completely dealt with is that of the spectroscope, which is 

 at once one of the most intricate and one of the most important 

 of the telescope accessories. The objective-prism, in ]iarticular, 

 is very briefly treated of. But these are but small ])oints. and 

 cannot detract from the immense value of the book as a whole. 

 It will form an invaluable adjunct to the library of every 

 observatory — for the whole wide field of astronomical instru- 

 ments has been covered with conspicuous skill, thoroughness, 

 and care — and it will be a complete reference book to any 

 astronomer who wishes to establish a telescope of his own, even 

 though his equipment be nece.ssarily a modest one. 



The Natural lli>it>irij of Sflborne. By Gilbert T. White. 

 Edited with Notes by Grant Allen. (John Lane.) Illustrated. 

 XII. Parts, l.s. tid. each. It is pleasant to think that among 

 the last literary work undertaken by the late Grant Allen was 

 the editing of an edition of White's classic letters. That this 

 was a most congenial task to Grant Allen we are certain, for he 

 knew the neighbourhood of >Selborne well, and was a great 

 admirer of the immortal Uilbert White. Although — as the 

 editor says in his delightful introduction to the volume — these 

 " letters have probably been reprinted in a greater number of 

 editions than those of any other English worthy,'' nevertheless 

 their present edition is very welcome. The aim has been to 

 preserve the original text ; and the editor's notes, which are 

 useful and not unnecessarUy frequent, are always signed, and 

 can, therefore, be immediately identified. No attempt has been 

 made to bring all White's statements up to the modern standard 

 of scientific knowledge — and rightly, for such a gigantic task 

 would utterly spoil the book. Everything in this edition — 

 from the editor's scholarly introduction to the excellent pen- 

 and-ink drawings by Mr. Edmund H. New — is in keeping with 

 the character of the letters. An appendix contains a novel 

 feature in some interesting marginalia from Samuel Taylor 

 Coleridge's copy, as well as a complete bibliography of the work. 

 Bacteria. By George Newman, m.d., f.r.s. (Murray.) Illus- 

 trated. 6s. Dr. Newman, according to the preface in this book, 

 had no other inspiration than an editor's request " to set forth a 

 popular scientific statement of our present knowledge of 

 bacteria," when he undertook to add one volume more to the 

 large number aheady in existence. With this sort of halter 

 round one's neck it is a hazardous ta.sk to traverse the uneven 

 ground covered by that now all-embr.acing, yet innocent looking, 

 word — bacteria. As the author says, '• it is difficult to escape 

 the Scylla and Charybdis in such a voyage." Too technical for 

 the many and too popular for the few, one or other of these 

 results is often arrived at in efforts of this kind. A medical 

 student, in his third or fourth year, would follow Dr. Newmun 

 with profit, but the average man, depending upon common sonaa 



