December 2, 1896.] 



KNOWLEDGE 



275 



plutonie rocks, intrusive rocks, and volcanic rocks. Each 

 of these classes is treated in a separate section, in which 

 the various rock-types are grouped in families founded on 

 the mineralogical composition. The two other sections 

 into which the book is divided refer respectively to 

 sedimentary rocks and metamorphism. The book contains 

 seventy-tive " process " illustrations of rock sections, and 

 though these cannot, of course, adequately represent the 

 natural appearance, they will be of great assistance to 

 teachers in showing structural characters. The book can 

 be confidently recommended to students of petrology, as a 

 clear and precise exposition of their subject. 



Chemists and their Wonders. By F. M. Holmes. Pp. 

 160. (Partridge & Co.) The aim of the author of this 

 volume has been " to present in a purely popular form some 

 of the remarkable instances in which chemistry has 

 influenced various industries during comparatively recent 

 years." The style is conversational, and suited to the 

 mental digestion of a juvenile public. As a book for the 

 young, containing a number of facts about chemical arts 

 and manufactures, the volume will probably be successful. 



Astronomers and their Observatories. By Lucy Taylor. 

 Pp. IGO. (Partridge & Co.) Books on astronomy are 

 fairly numerous, but we think there is room for this little 

 one. The authoress writes pleasantly, clearly, and 

 accurately, and her readers will obtain a good all-round 

 knowledge of celestial science. 



Architecture for (renernl Readers. By H. Heathcote 

 Strahan. Pp. 332. (Chapman & Hall.) There are 

 many who take an interest in architecture, but lack the 

 knowledge which would enable them to understand the 

 different styles, and to come to an intelligent judgment on 

 architectural designs. This treatise supplies the outlines 

 of the principles, practice, and historical development of the 

 art, and anyone who reads it will be able to distinguish the 

 good from the bad in the design and construction of 

 buildings. Mr. Strahan is the editor of the Builder, and 

 therefore he writes as one who knows. His book is 

 admirably planned and attractively written, and those who 

 read it will not only be interested, but wiU be given at the 

 same time an additional source of pleasure in life. 



British Birds. By W. H. Hudson, C.M.Z.S. (Long- 

 mans.) Illustrated. Of the many bird books recently 

 published, this volume must be ranked among the best. 

 It is not intended as a text-book for the student, but as a 

 book to interest the general reader, and especially the 

 young, in the birds of our islands. Those birds only are 

 dealt with which may be termed strictly British at the 

 present time. Thus, of the three hundred and seventy- 

 six so-called British species, the author has omitted 

 from the present volume the hundred or so which 

 may be described as " accidental stragglers," rightly 

 concluding that a bird cannot be called "British" if it 

 has only visited our islands on a few chance occasions. 

 Some time ago Mr. Hudson penned a pamphlet on 

 " Lost British Bu'ds." In the list of birds supposed to be 

 lost to our islands we are sure that Mr. Hudson was 

 pessimistic, and we are glad to see that he has included 

 in his present volume several species which he formerly 

 considered as lost. Of these, the bittern is figured in one 

 of the several beautiful coloured plates which adorn the 

 book. These plates are the handiwork of Mr. Thorburn, 

 and we have never seen better. Mr. Lodge is responsible 

 for a number of smaller drawings — -most of them finely 

 drawn and true to nature, although some of them are too 

 crowded. Mr. Hudson's descriptions are brief, but his words 

 are those of a true lover of birds, and they cannot fail to 

 interest the reader, be he young or old. Tlie following 

 passage may be taken as typical of the author's picturesque 



style :— " At all seasons the jackdaw loves to consort with 

 his fellows, and to spend a portion of each day in aerial 

 games and exercises ; the birds circle about in the air, 

 pursuing and playfully buffeting one another, and tumbling 

 downwards, often from a great height, only to mount 

 again, to renew the mock chase and battle, and downward 

 fall." The value of the book is greatly enhanced by an 

 excellent chapter on the structure and classification of 

 birds by Mr. F. E. Beddard, a well-known authority on 

 the subject. 



The Splash of a Drop. By Prof. A. M. Worthingtou, 

 F.E.S. _ (S. P.'C. K.) Illustrated. This very interesting 

 volume is a capital addition to the "Romance of Science" 

 series. It is a reprint of a discourse delivered at the 

 Royal Institution, a year ago. Prof. Worthington has 

 been studying the curious phenomena for twenty years. 

 The splash of a drop occurs in the twinkling of an eye ; 

 yet it is an exquisitely regulated phenomenon, and one 

 which very happily illustrates some of the fundamental 

 properties of fluids. The problem which Prof. Worthington 

 has succeeded in solving is to let a drop of definite size fall 

 from a fixed height in comparative darkness on to a surface, 

 and to illuminate it by a flash of exceedingly short duration 

 at any desired stage, so as to exclude all the stages previous 

 and subsequent to those thus selected. The numerous illus- 

 trations in the volume testify to the accuracy and beauty 

 of his work. The curious results of the splash of a drop 

 of mercury from a height of three inches upon a smooth 

 glass plate are particularly interesting. Very soon after 

 the first moment of impact, minute rays are shot out in 

 all directions on the surface with marvellous regularity. 

 Prom the ends of these, minute droplets of liquid split off'. 

 The liquid subsides in the middle, and afterwards flows 

 into a ring. The ring then divides in such a manner 

 as to join up the rays in pairs. Thereafter the whole 

 contracts, till the liquid rises in the centre, so as to 

 form the beginning of the rebound of the drop from 

 the plate. Immediately the drops at the ends of the arms 

 now break off, while the central mass rises in a column 

 which just fails itself to break up into drops. He photo- 

 graphed no fewer than thirty successive stages of the splash 

 within the twentieth of a second, so that the average 

 interval between them was about the six hundredth of a 

 second. Remarkable are the splashes of water-drops falling 

 about sixteen inches into milk, but mare beautiful are the 

 dome forms when the height is fifty-two inches. The 

 study of a splash of a drop is so unique and interesting 

 that all of a curious turn of mind should secure the little 

 volume. 



BOOKS RECEIVED. 



Tke Structure and Development of the Mosses and Ferns. By 

 Douglas H. Campbell, M.D. (ilacmillan.) Illustrated. 14s. 



A Laboratory Course in Experirrtenfal Physics. By W. J. 

 Loudon, B.A., and J. C. McLeunau, B.A. (Macmillan.) Illustrated. 

 83. Gd. 



Perijyatus, Myriajiods, and Insects. Bv Adam Sedgwick, M.A., 

 F.B.S., F. G. Sinclair, M.A., and David Sharp, M.A., F.R.S. 

 (Macmillan.) Illustrate! 17s. 



A ILandhook of the British Lepkloptera. Bv Edward Meyrick. 

 (ilacmillau.) 10s. 6d. 



Natural History of the Drone-Fly. By Ct. B. Buckton, F.R.S. 

 (Macmillan.) Illustrated 5s. 



An Exercise Book of Elementary Praeticxl Phi/sics. Bv R. A. 

 Gregory, F.R.A.S. (Macmillan.) Illustrated. 23. Gd. 



Text-booi of the Embryology of Invertebrates. By Dr. E. 

 Korsclielt and Dr. K. Heider. Transkted by E. L. Mark and 

 W. Moil. Woodwortli. Part I. (Swan Sonneuschein.) Illustrated. 



153. 



British Birds' Nes's. By R. Koarton. (Cassell & Co.) Illustrated. 

 A Hand-book of Industrial Organic Chimistn/. By S, E. Sadtler, 

 Ph D., F.C.S. (Lippincott.) Illustrated. 



