will also appreciate the hundreds of new problems (over 1,000 problems total) that are available for homework assignments and c1assroom discussions. Answers to most problems are Iisted at the back of the book, so that problem-solvers can have the satisfaction of checking their results. References and historical notes are also collected at the back of the book. They include the original sources of the subject matter and biographical notes about the pioneering engineers, scientists, and mathematicians who created the subject. The book concludes with an extensive and care fuIly prepared index, which makes it very easy to locate any desired sub ject matter. This third edition of Mechanics of Materials has been thoroughly rewritten with improved discussions, many new problems, and some changes in organization to make the book more useful in the c1assroom. Discussions of fatigue and stress concentrations in axialload, torsion, and bending have been added, and a few specialized topics ha ve been dropped. AII changes in the subject-matter coverage were prompted by the sug gestions of teachers who were familiar with the second edition. Every effort has been made to eliminate errors, but if you find any, please jot them down and mail them to the author (Department of Civil Engineering, Stanford University, Stanford, California 94305-4020); then we can correct them immediately for the next printing of the book.