August 24, ign] 



NATURE 



241 



when precedents have to be Mirpassed or greater speeds 

 obtained. They can be applied both to the determina- 

 tion of the ship-forms most suitable under the con- 

 ditions of a given problem, and to the selection of the 

 most efficient propellers. 



The first experimental tank, designed and built by 

 Froude, was placed at Torquay, near his residence. It 

 was comparatively modest in size and equipment, and 

 was not intended to be permanent; but it continued at 

 work for many years, first under the direction of the 

 founder, and then under that of his son (Mr. R. E. 

 Froude, F.R.S.), and yielded remarkable results, 

 greatly to the benefit of the designs of ships of the 

 Royal Navy. About twenty-seven years ago the Ad- 

 miralty decided to construct at Haslar (near Ports- 

 mouth) a larger and better equipped experimental 

 tank, to the designs of Mr. R. E. Froude, who has 

 happily continued ever since in charge of its opera- 

 tions, and has greatly developed the system. This 

 Admiralty tank has been the pattern adopted for tanks 

 subsequently established in this country by a few lead- 

 ing firms of shipbuilders, and for many tanks estab- 

 lished abroad. France, Germany, Russia, Italy, the 

 United States, and Japan have followed the lead ; and 

 the latest, largest, and best equipped of the series is 

 that which has been added to the National Physical 

 Laboratory by the generosity of Mr. Yarrow. The 

 primary purpose of that tank is the conduct of sys- 

 tematic experimental research, and great results may 

 confidently be anticipated from its operations. Previous 

 tanks have necessarily been chiefly devoted to experi- 

 ments on models representing ships which are to be 

 built, and pure research work has had to yield to more 

 pressing requirements. At the same time, it is but 

 fair to recognise the fact that many very valuable 

 results of a general character, influencing the selection 

 of the most suitable ship forms and propellers, have 

 been published already. Mr. R. E. Froude (with the 

 sanction of the Admiralty) has been the principal con- 

 tributor; but Mr. Taylor, the superintendent of the 

 united States tank, Colonel Rota of the Italian Navy, 

 Prof. Sadler of Michigan University, and others have 

 added to available information. Prof. Biles has sum- 

 marised and analysed the results of tank experiments 

 in the present volume, and has undertaken the labour 

 of presenting the facts in a condensed and practical 

 form ; he has thus rendered a service to all who are 

 interested in the subject. 



Closely connected with the resistance experienced 

 by ships in motion is the subject of propulsion, which 

 is treated in the third section of this- book in an ade- 

 quate and practical fashion. Model experiments on 

 propellers have been, and are of great value, but they 

 require to be supplemented by trials on full scale. The 

 author has brought together available data and indi- 

 cated the need for further information. He states the 

 conditions which chiefly govern the efficiency of screw 

 propellers, and gives details of the methods of design- 

 ing them. Progressive speed trials of actual ships are 

 described and recommended, and there is universal 

 agreement that such trials are essential to success in 

 the practical application of model experiments. 

 Numerous examples are given of the results obtained 

 from experiments both on ships and models. 

 NO. 2l82, VOL. 87] 



The subject of the oscillations of ships in still 

 water and among waves furnished the opportunity for 

 a second great contribution by the elder Froude to the 

 science of naval architecture. His work in this direc- 

 tion really constituted a new departure in ship-design. 

 Much has been learned from experiments both with 

 ships and models since Froude indicated the way, and 

 a great deal has been done towards endowing ships 

 with greater steadiness and limiting their oscillations. 

 This result has been due in part to a better under- 

 standing of the problem and partly to the use of bilge 

 keels, moving weights, internal water tanks, and other 

 special arrangements the action of which tends to limit 

 the range of oscillation of ships in a sea way. These 

 arrangements are discussed by Prof. Biles, and the 

 effects produced by their use are illustrated by results 

 observed on board ships when in actual service at sea. 



Although this book is primarily intended for the use 

 of students of naval architecture, it will be seen from 

 the foregoing summary of its contents that it deserves 

 a wider circulation. It should, in fact, have an in- 

 terest not merely for students and naval architects, but 

 be welcomed by mathematicians and others, to whom 

 the subjects treated and the experimental results 

 recorded should offer many attractions. \V. H. W. 



JURASSIC AND CRETACEOUS 

 STRATIGRAPHY. 

 Traiti- de Geologic. By Prof. Emile Haug. Vol. ii., 

 Les Periodes geologiques, fasc. 2. Pp. 929-1396. 

 (Paris : A. Colin, n.d.) Price 10 francs. 



THE Jurassic and Cretaceous systems were for 

 long the most popular among British geologists, 

 and the former will always be of special interest as 

 the principles of historical geology were established 

 by William Smith from work on the Jurassic rocks 

 of rln- south-west of England. The second part of the 

 second volume of Prof. Haug's "Traite de Geologie " 

 is devoted to these two systems, and we are glad to 

 note that he retains the Rhaetic in the Jurassic. The 

 work is of great value as a summary of a wide range 

 of recent research, and its excellent photographs illus- 

 trating many well-known Continental localities are 

 of unusual artistic merit. The book is a useful com- 

 plement to the great treatise of de Lapparent, with 

 its invaluable tabular correlations. Prof. Haug gives 

 short, readable summaries of the stratigraphical classi- 

 fication and geographical distribution of the forma- 

 tions, and deals especially fully with the bathymetric 

 conditions of their disposition. Lists of characteristic 

 fossils are given, and he wisely gives only generic 

 names. Exception may be taken to some of his 

 palaeontological conclusions, such as the affinity of 

 Tetracidaris to Archaeocidaris. 



The amount of space devoted to different areas is 

 very uneven. In spite of the historic importance of 

 the' English Mesozoic rocks, they receive very scant 

 attention. Thus the list of literature on the Jurassic 

 contains 361 titles, of which only eighteen, including 

 eight by Mr. Buckman and two by Prof. Pavlov, deal 

 with the British Jurassic. He apparently considers 

 that British Jurassic geology has not been kept up 

 ' s to date, and remarks that it is difficult to determine 



