KNOWLEDGE & SCIENTIFIC NEWS. 



[Arr.rsT, 1905. 



it may be that a more correct idea of the relative importance 

 of the various bodies can be thus ol)tained. The unit on which 

 all the measurements are made is the light-year, and there is 

 a fortunate coincidence in the fact that if the dislaiue uhicli 

 light travels in one year be represented hy one mile, thin the distance 

 of the earth from the Sun will be represented by one inch on the same 

 scale. Based on this idea, a series of maps are presented, 

 showing the positions of the members of our solar system, all 

 stars within the distance of 60 light-years, and those within 

 430 light-years. These are compared with known terrestrial 

 distances in order to fix ideas. Next an endeavour is made to 

 present a stereoscopic chart of the stars, the size of the relative 

 images being made proportional to their sun-power. The dis- 

 tance between the two images is taken as 107 light-years, and 

 the distances plotted according to the best determined parallaxes. 

 The stereograms given are very interesting, but, beyond giving 

 a concrete illustration of the effect of parallax, cannot be con- 

 sidered as showing the actual distribution of stars in space. 

 An appendix contains useful lists of stellar magnitudes, spectral 

 types, and parallax values. 



Our Stellar Universe, by T. E. Heath (King, Sell, and 

 Olding, Ltd., 1905; 3s. net). — This little volume contains six 

 stereograms of the sun and surrounding stars, and is intended 

 as a companion to the author's larger work above mentioned. 

 An index of all the objects shown on each chart is included, 

 with the individual magnitudes, comparative sun-power, and 

 spectral type. 



The Hand Camera and What to do With It, by W. L. F. 

 Wastell and K. Child Bayley (Iliffe and Sons; price is. net). — 

 The photographic possibilities, and the principles that underlie 

 them, in the use of hand cameras is a very large subject. But 

 practical work of the kind that has come to be known as 

 " snap-shotting" is so simple that those who indulge in it are 

 apt to underrate the value of a general knowledge of the facts 

 that their results depend on. AH such, as well as beginners in 

 the art, will reap considerable advantage without much intel- 

 lectual effort by reading this volume. The authors deal with 

 the purchase of a camera, the several types of cameras and 

 their various parts, the manner of their use, the development 

 of the negatives, and the preparation of prints and enlarge- 

 ments from them. The information given is practical and 

 reliable and well selected. The volume takes the place of one 

 written a considerable time since by Mr. Welford, and perhaps 

 this accounts for the inclusion of the " uniform system " of 

 marking lens diaphragms, which was never widely adopted, 

 and was officially withdrawn many years ago by the Royal 

 Photographic Society, who were responsible for its intro- 

 duction. Half-a-dozen good reproductions of hand-camera 

 pictures are given, four of which are of architectural subjects, 

 and serve to show the use of the method in a sphere that too 

 many regard as altogether outside its scope. 



The Nature o( Explosions in Gases. H. B. Dixon, F.R.S. 

 (Henry Frowde ; i5. 3d. net). — This is the tenth Boyle lecture, 

 delivered before the Oxford University Junior Scientific Club, 

 and deals in particular with the mode in which flame is propa- 

 gated in explosions and the nature of the chemical reactions 

 occurring. Reference is made to the fact that it was while 

 repeating Bunsen's work that he discovered that a dried mix- 

 ture of carbonic oxide and oxygen would not explode under 

 the action of a spark which readily kindled the moist mixture. 

 The main part of this lecture is concerned, however, with the 

 rate of explosion. Berthelot showed this rapidly increases 

 from its point of origin until it reaches a maximum which 

 remains constant however long the column of gases may be. 

 Mr. Dixon considers that the wave must be propagated not 

 only by the burnt but equally by the unburnt molecules (with 

 which the former exchange velocities), and that therefore half 

 the unburnt molecules are heated by the collision before they 

 are burnt. He finds an extraordinary close agreement 

 between the rate calculated from this point of view and the 

 actually observed rates. Some photographs of compression 

 waves through heated gases are reproduced and discussed. 



We have received Electricity No. 21, Vol. XIX; and The 

 Indian Electrical and Mechanical Textile News, No. 8, Vol. II. 

 (Bombay), containing amongst articles of interest on electrical 

 and other topics a capital portrait of Sir Joseph Wilson Swan, 

 F.R.S. 



Suggestions Towards a Theor>' of Electricity Based on the 

 Bubble Atom. John'Fraser. — This is a reprint from the Procued- 

 ings of the Royal Society of Edinburgh. It is very diflicult to 

 appraise the theory which is here presented, because the author 

 is not very clear in the way that he brings it forward. It is 

 obviously highly original, although it bears certain resem- 

 blances to Osborne Reynolds' theory of matter. On both 

 theories matter is supposed to be represented by gaps in the 

 ether. On Mr. Eraser's theory the ether is prevented Iromfalling 

 into these gaps by the rapid motion of the particles forming 

 the surface of the gap. We cannot follow the author into his 

 applications of his theory to the elucidation of the electrical 

 properties of bodies. Hut we must remind him that a tremen- 

 dous quantity of experimental facts are now known, and any 

 theory which hopes for a long life must be capable not only of 

 explaining these but also of keeping step with the rapid pro- 

 gress of discovery. If Mr. Frascr will find some friend more 

 skilled in the art of advocacy than he seems himself to be, it 

 is possible that the numerical correspondences which he dis- 

 plays in a table at the end may be shown to have a great value 

 in guiding theoretical physicists to a correct view of the con- 

 stitution of matter. 



Practical Gum-Bichromate, by J. Cruwys Richards (Iliffe 

 and Sons; price 2s. 6d. net). — This process, which has lately 

 been in great favour with those who like to alter their photo- 

 graphic results to suit their taste, is here described by a 

 practised hand. The directions are so plain and straight- 

 forward that anyone may follow them ; but, of course, the 

 worker's success, from a pictorial point of view, must depend 

 upon his skill and artistic knowledge, for this alone can guide 

 him in the " local treatment," and the putting in of '• bright 

 specks" by means of " the point of a penknife, or a dry brush, 

 or anything else that experience may dictate." The author 

 has given his own methods of work and his own preferences ; 

 but he has added the formulae for coating the paper as used by 

 several other well-known and successful workers of the process. 

 The illustrations are excellent guides to the appearance of 

 prints at various stages of their production, especially in the 

 multiple printing methods. 



Unbeaten Tracks in Japan, by Isabella L. Bird (Mrs. Bishop) 

 (London: John Murray, 1905 [Popular Edition]; 2s. 6d.). — In 

 issuing a cheaper and popular edition of this charming volume 

 we venture to think some intimation should have been given 

 to the effect that this book is concerned with Japan as it was 

 some sevenandtwenty years ago. It would also have added 

 much to the convenience of the reader if the full dates of the 

 several letters, which make up the chapters of this work, had 

 been added. Only here and there do we get anything nearer 

 than " May 30 " or " August 24." The first letter appears to 

 have been written on May 21, 1878, the last on December 18 

 of the same year. 



We suspect that the horrible neglect of sanitation so vividly 

 described by Mrs. Bishop is to-day, for the most part, a thing 

 of the past, even in the out-ofthe-way regions described. 

 Certainly we hope that the unspeakable cruelty which appears 

 to have been practised on horses has long since ceased. 



This book is too well known to need a Ipng description. In 

 its new and most attractive form it should gain a large number 

 of fresh readers. 



Wasps Social and Solitary, by George W. Pcckham and 

 Elizabeth G. Pcckham (A. Constable and Co.; price 6s. 

 net). — It is difficult for the casual reader to ascertain the 

 exact object of this book, and whether it is intended for 

 the nursery, schoolroom, or as a scientific treatise. The 

 plain and childlike language and the simple and, we may 

 say, unscientific methods of observation described would 

 lead one to suppose its object was to instil into the juvenile 

 mind an interest in natural hii^tory. ^'et there is something 

 more than this in the book. The careful observations noted 

 and recorded have their value to the student, and the habits 

 of some species of wasps are well worth noting and recording. 

 The detailed account, for instance, of an Ammophila making 

 its nest in the ground, filling up the hole, and then pounding in 

 the grains of sand by means of a small pebble held in its 

 mandibles, is certainly most interesting. The illustrations 

 are by James H. Emerlon, whose age is not given, but we 

 should doubt whether his talent', when he grows up, would 

 qualify him for Academic honours. 



