Many people have helped us in assembling material for this book or have helped in other aspects of its production. To all of them we are happy to express our gratitude.

Foremost on our list is Dr. Ira M. Freeman, professor of physics at Rutgers University. It was to him we went to learn the mechanical principle governing the action of the club in the last quarter of the downswing. His answer, the Con­servation of Angular Momentum, cleared up one of the most puzzling aspects of the swing and became part of the founda­tion of this book.

Much of Dr. Freeman's conclusion was based on his study of multi flash photographs made by Dr. Harold E. Edgerton of Massachusetts Institute of Technology. To Dr. Edgerton we are indebted for the use of two of his photographs in this book, and for his sympathetic attitude toward our problem.

Our thanks also go to Jack Johnston, a Newark News pho­tographer. He took several of the photographs we reproduce, and from hundreds more which he made (as well as several taken by Edward Dubin, a Rockaway River Country Club member), artist William Canfield made his drawings. Inci­dentally, all the drawings showing action were made from action photographs. There is no posed "action" in the book.

We thank golf professional Wesley Ellis for permitting us to use a photograph of his swing and for his appearance in certain of William Canfield's drawings.

Jimmy Demaret's remarks about the closed face and the early wrist break appeared in Golf Magazine, February, 1961, and for their inclusion we are indebted to Charles Price of that magazine. Helen Dettweiler's observation about the early wrist break appeared in Golf Digest, December, 1958, and Bill Casper's remark about his body swinging the club ap­peared in Golfing, June, 1960; our thanks to the editors, re­spectively Howard Gill and Herb Graffis, for permission to use the material.

Finally, our thanks go to A. G. Spalding & Brothers for tech­nical information about club manufacture; to Dr. Lewis W. Brown for guidance on human anatomy; to T. Desmond Sullivan, former president of the Golf Writers Association of America; to Geoffrey Cousins, honorable secretary of the Association of Golf Writers, Great Britain; to Earl H. Tiffany, Jr., for the photograph of the bad hitting position; to Al Beissert, art director of the Newark News, and Dr. Glennis B. Rickert for their many favors.

j. D.
L.   E.