In 1947, Professor H. S. Miles, Jr. of the Mechanical Engineering Department at the Virginia Polytechnic Institute, presented a thesis (1) on the design of a 65 ton steam jet refrigeration unit. Miles recommended that a small unit be constructed in the Mechanical Laboratory so that the soundness of his design be confirmed. With this in mind, Messrs. A. W. Howard and C. W. Vogelsang (2) built a 5 ton unit in the laboratory in 1948. It is the purpose of the authors of this report to determine why the steam jet refrigerating unit constructed in the Mechanical Laboratory at the Virginia Polytechnic Institute in 1948 did not reach design capacity. / M.S.