Wilbert F. Stoecker is Professor Emeritus of Mechanical Engineering at the University of Illinois at Urbana-Champaign, and the author of McGraw-Hill�s Refrigeration and Air Conditioning, now in its second edition. For 12 years, he has been a science adviser for the International Institute of Ammonia Refrigeration as well as a member of its research committee. Mr. Stoecker is also an associate director of the semiannual Industrial Refrigeration Workshop, a week-long course in which he also serves as a presenter.