210 



KNOWLEDGE. 



[September 1, 1900. 



Among the honours which may in some degree have compensated 

 Xansen for the hardships of his I'ohir experiences, this fine con- 

 tribution to the scientific results by his distinguished brother-in-law 

 is entitled to stand in the front rank. — T. R. K. S. 



" WiBELESS Telegraphy and Hertzian Waves." By S. R. 

 Bottone. (Whittaker.) 3s. The fourth and last chapter of this 

 volume occupies nearly half the book, of which it forms by far the 

 most useful and interesting portion. The author is evidently well 

 versed in the requirements of the numerous amateur electricians 

 who have much enthusiasm but few tools and little knowledge 

 of their use. To amateurs of this class we can recommend the 

 volume for the sake of this chapter. The instructions both for 

 making and using the apparatus are given with such minute atten- 

 tion to practical and essential details that it is evident that the 

 author has himself experimented with apparatus constructed 

 by him in the manner wliich he describes. The introductory 

 chapter is the least satisfactory part of the book. The very brief 

 statement of certain elementary electrical facts would be of very 

 little if any assistance to a reader having no knowledge of the 

 subject and superfluous for others. Tarts of it, moreover, are 

 misleading. Both on pages 1 and 12 it is stated that an electrically 

 charged liody consists in rapid molecular vibration, and on page 3 

 it is suggested that conductors are bodies which freely transmit 

 electrical vibrations while insulators do not. Now one of the 

 things we do Icnow about electricity is that insulators are the 

 best transmitters of electric waves, and that the better con- 

 ductor a body is, the more imperfectly does it transmit 

 these waves, indeed a theoretically perfect conductor would act as 

 an absolute screen to the transmission of electric action, being im- 

 penetrable to electric vibrations. On page 10, again, the author, 

 referring to the strained condition of the insulating medium near 

 electrically charged bodies, treats the air as a rigid substance, and 

 does not seem to be aware of the physical properties of gases. 



We should advise the author in his next edition to sujipress this 

 chapter entirely, and devote the space to enlarging chapter II., 

 which might be done with advantage. It would also be advisable 

 in a new edition to draw a clearer distinction between Mr. Preece's 

 system of wireless telegrai)hy by means of electro-magnetic iu- 

 iluction, and the utihzation of the Hertzian waves which forms the 

 basis of the system which has been brought into practical shape 

 mainly by the indefatigable industry and skill of Mr. Marconi, 

 aided as he has been by Mr. Preece and the resources of the British 

 Postal Telegraph Department. 



■' Object Lessons in Botany." Book II. By E. Knelgrove, b.a. 

 (Jarrold.) Illustrated. 3s. 6d. One hundred lessons from forest, 

 tield, wayside, and garden, are herein embodied and neatly illus- 

 trated with simple woodcuts. The author's ideal in planning his 

 work is thus expressed — " Whether education or mere instruction 

 be its aim, that book is most likely to succeed that leads its readers 

 along the same paths as the discoverers of the science must them- 

 selves have followed. Students should not have facts thrust at 

 them, but should be shown how to find them out ; steps should 

 be made, not simplj- taken ; conclusions should be drawn, not 

 merely stated ; definitions should be led up to and not started 

 from." The lessons are designed to suit the cajjacities of children 

 from nine to eleven years of age, and we think Mr. Snelgrove has 

 veiy closely approximated to the laudable standard he set out to 

 attain. 



" Chatty Object Lessons in Nature Knowledge." By 

 F. W. Hackwood. (Longmans.) Illustrated. 3s. 6d. Here are 

 brought together, in convenient form, a good selection of outline 

 lessons on the common objects of nature. Teachers who experience 

 dilEculty in preparing object-lessons of this kind will find ih. 

 Hackwood very helpful in the way of suggestion. A number of 

 drawings, white on black, are scattered throughout the volume to 

 serve as auxiliaries to the teacher in sketching on the blackboard 



"The Struggle for Kmpike." By Robt. W. Cole. (KUiot 

 Stock.) Mr. Cole in these pages makes an ingenious attempt to 

 describe a great war between England and the inhabitants of the 

 star Sirius in the year 2236 a.d. Those who enjoy foUowing in the 

 wake of the visionary may here find jileasant reading for an hour 

 or two. War ships of the future according to the author's notion 

 wiU be closely allied to Jules Verne's " CUpper of the Clouds." 

 Of course, in the war with Sirius England wins, but only after a 

 great sacrifice of hfe and shijjs. It is interesting to observe that 

 the war office of this future period is credited with the fault 

 ascribed to that of the present day, namely, unpreparedness. 



"An Essay on Mental Culture." By G. A. Hight. (Dent.) 

 3s. 6d. net. Our author seeks to impress on the mind the supreme 

 imiJurtance of intellectual culture in these latter days, and the 

 necessity for self-reliance in the solution of the many perplexing 

 ijuestions evolved by advanced thinkers. The book is an essay — 

 nothing more; it contains much sound matter with which all 

 thoughtful readers will agree, but a considerable portion is dis- 



torted by a strong personality. Plain speaking, indeed, is the most 

 characteristic feature of the essay ; right or wrong the author may 

 be, yet truth and error are delivered with the same unreserve. 

 - " Signalling Through Space Without Wires.'' (The work 

 of Hertz and his successors.) (" Electrician" Publishing Co.) ii. and 

 133 pages. This is the third edition of Professor Lodge's weU- 

 knoMTi little volume, generally known by the second title quoted 

 above, which formed the first'title in the first two editions. This 

 third edition cuntains some 27 pages of interesting additioiuil 

 matter, including notes on his own recent researches in syntonic 

 telegraphy. In referring to Professor Slaby's work on Spa'-k 

 Telegraphy, and to his having succeeded in signalling from 3 to 13 

 miles across laud. Dr. Lodge inadvertently does an injustice to 

 Marconi in not jiointing out that, according to Professor Slaby 

 himself, he had not got beyond 50 metres until after he had 

 witnessed Marconi's earlier demonstrations. 



"The Flowering Plant." 3rd Edition. By J. R. Ainsworth 

 Davis, M.A. (Griffin.) Hlustrated. 3s. 6d. Actual dissection 

 of the plants studied is insisted on by the author of the book 

 under notice, to facilitate which easily obtained objects are figured 

 and described instead of rare and often inaccessible ones. A 

 special chapter on ferns and mosses forms the chief feature in 

 this edition, an innovation which will be appreciated by most 

 teachers, seeing that these plants are abundant everywhere and 

 so imperfectly understood outside the ranks of the specialists. 



" The Theory and Practice of Interpolation." By Herbert 

 L. Rice. (Nichols Press : Lynn, Mass.) Professor Rice endeavours 

 to give a simple, practical, yet comprehensive discussion of all 

 that is useful concerning diiierences, interpolation, tabular 

 differentiation, and mechanical quadrature — a complete exposition 

 of all the tables required by a practical computer. Many of the 

 tiibles are here printed for the first time, and are true to the nearest 

 unit of the last figure. We note with regret that references to the 

 writings of Walmesley, Mouton, and Lalande have been purposely 

 omitted " because of the general inaccessibility of their works." 

 Although the author has used with discretion the works of such 

 writers as Encke, Loomis, and Newcomb, he has drawn very 

 largely on his own resources in preference to the usual forms of 

 analysis, but the subordination of facts and figures has been so 

 thorough and masterly in the Professor's hands that we feel con- 

 vinced the fundamental principles involved stand out the clearer as 

 a result. The comj utations were all made in duplicate by indepen- 

 dent methods, so that the absolute of accuracy is thus as near 

 as may be attained. 



" Ferric and Heliographio Processes." By George E. 

 Bi'own, E.i.c, (Dawbarn & Ward.) Illustrated. 2s. net. Prac- 

 tical in character and hmited in scope, this book is intended 

 to supply amateur photographers, draughtsmen, engineers, archi- 

 tects, surveyors, and others, who find the reproduction of tracings 

 and drawings a matter of cvery-day necessity, with just enough 

 exact knowledge to duplicate pictures and drawings by the so- 

 called " blue jnocess." Many devices are employed for varying 

 the background so as, for example, to get a brown or other colour 

 in place of the TurnbuU's blue — eflects produced by the employ- 

 ment of tinted paper or other means. Thorough working details 

 are presented so that anyone with the aid of this book may readily 

 master all the phases of the art. 



"Life and Correspondence of Dr. Arnold." By Dean 

 Stanley. (Ward, Lock.) Illustrated. 2s. "Arnold of Rugby" 

 is a name more or less familiar to all. When we mention the fact 

 that this work went through twelve editions during the late 

 Dean's lifetime, its merits will be sufficiently apparent. The chief 

 point about the present edition is that the book is piresented in a 

 most attractive form at a price within the means of the largest 

 number. By far the greater portion of the volume is occupied with 

 the great teacher's correspondence suitably interspersed with bio- 

 graphical details by his devoted pupil. Two good portraits of the 

 master are given, together with views of the places Dr. Arnold 

 was associated with during his lifetime. 



We have received the August issue of the "' Theosophical Review ' 

 (Is.), the organ of the Theosojihical Society, containing contribu- 

 tions from Dr. A. A. Wells, Mr. A. H. Ward, and other writers. 

 Persons interested m the subjects treated of in the Review should 

 communicate with the Hon. Otway Cuffe, at 28, Albemarle Street, 

 I ondon. The publications of the Theosophical Publishing Society 

 may be obtained at o, Langham Place, London. 



We have received two catalogues of physical apparatus from 

 Messrs. Griffin, which will recommend themselves to those science 

 teachers who are engaged in organised courses, and also to students 

 working up for the London University practical examinations. 

 This fiirm has adopted the excellent idea of making up complete 

 sets of apparatus to suit the experimental portions of most of the 

 well known text-books, and thus a great deal of time may be saved 



