Mechanisms and machines have considerable fascination for most students of mechanical engineering since the theoretical principles involved have immediate application to practical problems. The main objective of writing this book has been to present the concepts in a logical, innovative and lucid manner. The basic theory presented in the book has been evolved out of simple and readily understood principles. A sincere effort has been made to maintain physical concepts in the various derivations. The use of simple mathematical methods instead of more elegant but less obvious methods has been preferred so that those with limited mathematical skill can easily understand the exposition.

An effort has been made to give a balanced presentation of the graphical and algebraic approaches. The method chosen is that which gives a sufficient-ly accurate solution with the least labour. Graphical techniques have been used frequently along with the simple algebraic methods as they usually economise on effort and time. The graphical differentiation technique given in the chapter on acceleration analysis would be of considerable help to the students in their practical classes.

Computers are increasingly playing a significant role in the modern world of advanced technology. Some computer-aided problem-solving techniques have been given in the chapters on computer-aided analysis and synthesis of mechanisms.

A number of worked examples have been included to reinforce the con-cepts. The International System of Units (SI) has been adopted throughout the book. A bibliography at the end has been added for the convenience of students interested in additional information.

An author is always helped and influenced by many during the writing of his book. Dr N P Mehta, Dr O N Kaul and Dr B S Gill of Regional Engineering College, Kurukshetra, are only a few of many whose help I would like to acknowledge.

It is but natural that some errors creep into a work of such volume. I would appreciate if any errors and shortcomings are brought to my knowledge. Sug-gestions for the improvement of the book would be also welcome.

Finally, I would like to make an affectionate acknowledgement to my wife Neena, and my children Ravneet and Jasmeet, for putting up with it all so cheerfully.

S S RATTAN