Historical Summary of Cryogenic Activity Prior to 1950

Abstract

Cryogenics is the science and technology dealing with temperatures less than about 120 K, although this historical summary does not adhere to a strict 120 K definition. The techniques used to produce cryogenic temperatures differ in severalways from those dealing with conventional refrigeration. In practice, these two areas often overlap and the boundary between conventional and cryogenic refrigeration is often indistinct. Significant reductions in temperature often have very pronounced effects on the properties of materials and the behavior of systems.