DISCOVERY 



109 



It should appeal to the amateur no less than to the 

 student. 



The author starts with a discussion of the celestial sphere, 

 and then describes the earth, the moon, and the sun. 

 Among the subjects considered may be mentioned the 

 size and motions of these bodies, their distances from each 

 other, the occurrence of eclipses and occultations, and the 

 phenomena of sunspots. Then follow two chapters 

 describing the latest astronomical instruments and 

 methods of making observations. Next comes an account 

 of planetary motion and a description of the planets and 

 their moons. Subsequent chapters are entitled " Comets 

 and Meteors," "The Stars," "Double and Variable Stars," 

 and " The Stellar Universe." The plates which adorn the 

 book contain a very representative set of astronomical 

 photographs. The author has been in a position to choose 

 them carefully, and he has seen to it that they have been 

 accurately reproduced. A. S. R. 



Synthetic Colouring Matters. Vat Colours. By J. F. 



Thorpe. C.B.E., D.Sc, F.R.S., and C. K. Ingold, 



D.Sc. (Longmans, Green & Co., 165.) 

 Indigo, derivatives of indigo and of the substance 

 anthraquinone are the most important members of the 

 series of colouring matters known as vat-dyestuffs. 

 These pigments are insoluble in water and many other 

 solvents, but by a slight chemical change may be made 

 soluble and then incorporated in the fibres of fabrics. 

 On exposure to the air the original insoluble pigment is 

 regenerated in the iibre, in which it becomes fixed 

 exceedingly firmly. Dyes produced by this method — 

 vat colours — are the fastest, most brilliant, and most 

 valuable of all colouring matters. Professor Thorpe 

 and his colleague. Dr. Ingold, have made a careful and 

 documented compilation of the principal properties of, 

 and processes relating to, these dyes, writing, as they 

 are qualified to do, both from the " theoretical " and the 

 "' practical " point of view. It is a book invaluable to 

 the organic chemist, and is a worthy member of Sir Edward 

 Thorpe's Monographs on Industrial Chemistry. The 

 publishers, too, are to be thanked for the general excellence 

 and accuracy of the printing (the misprints we have 

 noticed do not confuse), and for the low price at which 

 a book for specialists of nearly five hundred pages is 

 offered for sale. 



Practical Chemistry. By Lyman C. Newell, Ph.D. 

 (G. G. Harrap & Co., Ltd., 6s.) 

 An American book which is not a " Practical Chem- 

 istry " as we understand the term, but a " first-year " 

 theoretical chemistry of an elementary kind, with the 

 usual facts clearly explained and the usual processes 

 well illustrated. The custom of American textbooks of 

 chemistry of having innumerable photographs of every- 

 thing described is not departed from. 



Introduction to the Plant Life of the Oxford District. I — 



General Review. By A. H. Church, M.A., F.R.S. 



(Oxford University Press, 3s. 6d.) 



The latest of Dr. Church's Botanical Memoirs (No. 13) 



is more popular in appeal than its predecessors. Its 



one hundred and thirty-five pages contain chapters on 

 the physical features of the Oxford district, on its primary 

 woodland, its subordinate and herbaceous flora, the 

 presence of the hand of man, and on artificial plant- 

 formations. Most of the book can be read and enjoyed 

 by all who, even though lacking an intimate knowledge 

 of botany, love the countryside which is described. There 

 are fifteen large photographs of wood and copse and stream 

 illustrating the flora of fast-disappearing districts in the 

 neighbourhood of Oxford. The book is good all through, 

 full of information of many kinds, and is worthy of a 

 botanist who knows thoroughly the district described. 

 It is of immediate interest to Oxonians and, as a record 

 of existing things, should be valuable in fifty or a hundred 

 years' time. 



Common Science. By Carleton W. Washburne. 

 (G. Bell & Sons, Ltd., 4s. 6d.) 



A collection of about two thousand questions asked 

 by children forms the foundation on which this book 

 is built. Rather than decide what it is that children 

 ought to know, or what knowledge could best be fitted 

 into some educational theory, an attempt was made to 

 find out what children wanted to know. The obvious 

 way to discover this was to let them ask questions. 



The questions collected were asked by several hundred 

 children in the upper classes of an American elementary 

 school over a period of a year and a half. The questions 

 gave a very fair indication of the parts of science in 

 which children are most interested. Physics in a simple 

 form came first ; astronomy next ; chemistry, geology, 

 ■ and such parts of physical geography as deal with weather, 

 volcanoes, and earthquakes came third ; biology with 

 physiology and hygiene made a close fourth ; but nature 

 study, in the ordinary school sense of the term, suggested 

 very few questions. Not all, however, are answered in 

 tliis book. Questions relating to descriptive astronomy 

 and geology have been omitted, and those relating to 

 biology have not been stressed. The book, indeed, 

 deals principally with physical and chemical principles. 

 Within its limits it is excellent. The information is 

 accurate and so presented that school boys and girls 

 may be entertained as well as informed. The book 

 is well illustrated by photographs of boys and girls doing 

 the large number of experiments described in the text. 

 It should make a good present for any boy or girl who 

 is developing an inteiest in physical science and who 

 wants to know such things as why the Leaning Tower of 

 Pisa doesn't fall over, how things stick to one another, 

 why it is preferable to face forward when alighting from 

 a moving 'bus, and what makes the ocean look green in 

 some places and blue in others. The chapter on Elec- 

 tricity is specially clear and well illustrated. The author 

 has his pupils repairing blown fuses, making arc-lamps, 

 electro-plating, and sending messages with a cigar-box 

 telegraph. 



The book just buzzes with information on all the 

 elementary scientific matters that crop up in the course 

 of everyday life. There must be few whom it cannot 

 interest. Teachers who require to give elementary scien- 



