This is an introductory text which should be accessible to beginning graduate students and most seniors in the mechanically based branches of engineering. While the reviewer would prefer, especially for an introduction, a more pedantic style which clearly delineates between primitives, definitions, axioms, theorems, and proofs, the conversational tone adopted here has proven to be more generally palatable to both students and teachers; and it is predicted that An Introduction to Therrnomechanics will enjoy the same wide acceptance as Professor Ziegler's other books. The first three chapters, on mathematics, kinematics, and kinetics, are based on Prager's Introduction to Mechanics of Continua. The next two chapters are concerned with thermodynamics and material properties. Chapters 6-11 are brief treatments of ideal liquids, linear elasticity, inviscid gases, viscous fluids, plasticity, and viscoelasticity. Chapters 12 and 13, on general tensors and large displacements, are fashioned after Theoretical Elasticity by Green and Zerna. Chapters 14 and 15 are devoted to a presentation of Ziegler's own notion of thermodynamic orthogonality and its immediate consequences. Finally, the last three chapters provide second looks at non-Newtonian fluids, plasticity, and viscoelasticity in light of the orthogonality principle. Of course, the thermodynamical aspects of therrnomechanics are still fraught with controversy, and there are even strong opinions on how best to develop the generally accepted mechanical aspects of the subject. The author has wisely chosen to present his views directly without criticism of or comparison to other approaches. However, the reviewer did notice several slips which transcend the realms of controversy and taste. In the development of stress, Cauchy's lemma (Newton's third law of action and reaction) is tacitly assumed. In the 'development of heat conduction, it is directly assumed that the heat flow per unit area is the inner product of the heat flux vector and the surface normal. This is analogous to starting with the stress tensor and then assuming that it operates on the normal to produce the stress vector. The concept of material frame-indifference does not appear at all in the book. Finally, both the printing and binding of the review copy were poorly done.

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An account is given of Eshelby's point-force method for solving elastic inclusion problems, and of his equations relating an in homogeneity to its equivalent inclusion. The introduction of complex variable formalism enables explicit solutions to be found in various two-dimensional cases. Strain energies are calculated. The equilibrium shape of an elliptic inclusion exhibits an interesting feature not previously expected. A fresh analysis of stress magnification effects is developed.

BONDS IN THE IROI~SILICIDE FeSi AND RELATED CRYSTALSsmall axial ratio, such as shown by AuSn (Pauling, 1947), might be assumed by FeSi. The axial ratio could adjust itself in such a way that the silicon atom would use its valence of 4 in forming four bonds with the surrounding six iron atoms, and the iron atom would use its extra valence 2 in forming two iron-iron single bonds, one with each of the iron atoms above and below it along the c axis. Similarly, the cesium chloride structure might be assumed by FeSi, each silicon atom then forming eight half-bonds with the iron atoms surrounding it in a cubic arrangement, and each iron atom forming eight half-bonds with silicon atoms, and six one-third bonds with the six adjacent iron atoms. It seems not unlikely that co-ordination number 6 (bond number ~) is more suitable for silicon in an intermetallic compound than co-ordination number 8* (bond number ½), and that, moreover, resonating iron-iron bonds, with bond number ½, are more stable than nonresonating bonds, with bond number 1. The actual FeSi structure would thus be preferred to the cesium * A substance in which the four bonds of the silicon atom show pivoting resonance among eight positions is Mg~Si, with the fluorite structure (Pauling, 1948).chloride structure for the first reason, and to the nickel arsenide structure for the second reason.We are grateful to Prof. J. H. Sturdivant for assistance with the experimental part of this investigation. The work reported in this paper is part of a series of studies of metals and alloys being carried on with the aid of a grant from the Carbide and Carbon Chemicals Corporation.References BeRliN, B. (1933) The atomic displacements in the transformation from austenite to martensite are described, and the strains involved are derived. It is shown that the tetragonality ofmartensite arises as a necessary consequence of the assumption that the iron and carbon atom displacements constitute a common homogeneous deformation. An explanation of the observed high indices of the habit plane of martensite of certain carbon contents is advanced.