This book is an attempt to explain hardness measurements of metals in terms of some of their more basic physical properties. It does not deal with the atomic and crystalline mechanism of elastic or plastic deformation, but starting with the elastic and plastic characteristics it shows that the hardness behaviour of metals may be expressed in terms of these characteristics. It is hoped that this presentation will provide, for physicists, engineers, and metallurgists, a better understanding of what hardness means and what hardness measurements imply. The book places an emphasis on the physical concepts involved, so that the non-mathematical reader may grasp and appreciate the general physical picture without needing to follow the more detailed treatment. From reviews: 'This book is clearly written and illustrated and can be warmly recommended to all those who are interested in the hardness of metals. It is without doubt the most important work on the subject to have appeared for many years.' Nature 'It is in its fresh and unusual approach to the subject that this book will appeal most. Work from a very wide field is collected and critically discussed, and the author is to be congratulated on a volume which should appeal to metallurgists, engineers and physicists.' Research '...this is a book which the mechanical testing engineer will wish to have ready to hand.' British Journal of Applied Physics 'The story makes fascinating reading, not only because of the wealth of new explanations it contains, but also because of the author's skill in presenting his arguments so clearly and simply. It is extraordinary how far he is able to go on the most elementary of mathematics.' Institute of Metals Metallurgical Abstracts 'Has succeeded in raising the subject of hardness from its background of empiricism to that of scientific theory...This book is recommended for the scientist who...is concerned with the indentation of solids...The mathematics is simple and the style is easy to read.' Applied Mechanics Reviews.