Introduction:

Over twenty years have passed since the editors at McGraw-Hill received the manuscript for the first edition of this book. Back then, they measured it up and declared it was more than they had bargained for—both in words and illustrations. So everyone looked at it, hoping to find chapters, or parts of chapters, that could be cut. After a while, it became evident that the book would be more helpful to its readers as it stood. So nothing was cut and the publisher kindly agreed to put out a longer and more profusely illustrated version than originally planned