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then the synchronous constant rotating load will lead the displacement by the same angle 0 and the eccentrici ty ratio is unchanged. It is only for the Sommerfeld conditions that the att i tude angle is 90 ° and the load vector then changes from lagging by 90 ° to leading by 90 ° . The 180 ° change is peculiar to the Sommerfeld conditions and it is not a general proper ty of plain journal bearings.

Chapter 8 illustrates one of the main weaknesses of the book in that sev- eral of the relevant papers in this field are not ment ioned and that where references are given, it is almost an "historical" reference to indicate how the subject has developed rather than a critical review of the work. The list of references is very useful, but the reader should be given a critical discus- sion of the content of these references and some comment on the validity of their arguments. For example, many of the early papers on bearing stability were based on a "quasi-static" approximation for the fluid film and there was very little agreement between the theory and experimental results for the onset of half-speed whirl. It was not until the 1960's that computer programs were developed for predicting the dynamic behavionr of the film and gave good agreement with the experiments. The reader should be given more guidance as to the developments which have taken place and the references which are now considered to be important .

Chapter 8 covers both translational and conical self excited instabilities, but unfor tunate ly the gyroscopic stabilisation first noted by Leicester in 1956 is mis-quoted. For half-speed conical instabilities, Leicester found that the relevant parameter was the difference between the transverse inertia and t w i c e the polar inertia, IT -- 2 I0, whereas Chapter 8 quotes IT - - I o .

The overall conclusion is that this is primarily a book on gas film lubrica- tion, with some extension to liquid film bearings. It is a book which will be of interest to those who already posses a good understanding of the theory of lubrication and rotor-bearing dynamics. It can be recommended as a reference book for those working on gas lubrication, but no t as an undergraduate text , nor as a book which gives a comprehensive view of the entire subject. The title is perhaps misleading and it might have been bet ter to use "Gas Film Lubricat ion" , even though this repeats the earlier title.

H. MARSH

F r i c t i o n a n d W e a r , by A.D. Sarkar, Academic Press, London, 1980. ISBN 0-12-619260-X, xvi + 423 pages, illustrated, hard cover £32.60/US$75.00.

The author has written a basic text on the phenomena of dry friction and wear which is suitable for newcomers to tribology who do not require an ex- tensive mathematical t rea tment but need a broad understanding of the fric- t ion and wear process.

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The coverage includes the basic principles of friction and wear, discussing various models to explain the phenomena. Experimental justification, or otherwise, seems to be left to the reader to seek from the wealth of refer- ences given. The discussion is ex tended to more specialised forms of wear, such as fretting, erosion, and that due to rolling contact. The influence of materials -- both metallic and non-metallic -- is reviewed. The link between theory and practice is well illustrated in separate chapters on brakes, dry rubbing bearings and bio-tribology.

A lot of ground is covered in this book and so the information is presented concisely but, nevertheless, clearly and in a readable manner. The book should serve as an in t roductory text on tr ibology and the reader wishing to delve deeper into a particular topic is given a broad range of references.

PETERBRADFORD

Shock Waves and High-Strain-Rate Phenomena in Metals -- Concepts and Applications, by Marc A. Meyers and Lawrence E. Murr (eds.}, Plenum, New York, 1981. ISBN 0-306-40633-0, xiii + 1101 pages, illustrated, hard cover US$95.00 {plus 20% outside the U.S.A.).

The subject matter within this book is essentially the Proceedings of the International Conference on Metallurgical Effects of High-Strain-Rate Defor- mation and Fabrication, which was held in Albuquerque, New Mexico in June 1980.

Fifty-eight chapters, each consti tuting a paper from the conference, are organised into nine sections which progress logically from fundamentals, through developments, to applications of high-strain-rate and shock phenom- ena. Both experimental and theoretical analyses are covered, and of particu- lar interest are the techniques which experimenters have evolved in order to address the particular problems associated with taking practical measure- ments of high-speed phenomena over very short periods of time. Section 1 presents a fascinating historical perspective and is followed by sections on high-strain-rate deformation, dynamic fracture, and adiabatic shearing. The next three sections, occupying almost half of the book, concentrate on shock waves: experimental techniques; fundamentals; and mechanical and microstructural effects. The final section deals with applications, namely dy- namic compact ion of powders, and explosive metal working and welding. A number of appendices provide further information on properties and charac- teristics of explosives and shock waves.

Particular at tention is paid throughout the book to metallurgical aspects and there are numerous photomicrographs. However, these are of variable quality and in one or two cases the reader is obliged to believe the authors rather than decipher the photographs.

The editors wish to present their book as "an enduring reference work and a teaching tool" , whereas the reader discovers a publication which conveys