ABSTRACT
Two intimately related scientific and technological achievements occurred in the field of high pressure research at the National Bureau of Standards (NBS) laboratory during the second-half of the 20th century. They are: the invention of the diamond anvil high pressure cell (DAC) in 1958 and the development of the optical ruby fluorescence method of pressure measurement in 1972. These two developments together stimulated the profound advances in high pressure research that evolved in the latter part of the 20th century. By 1971, the DAC had undergone several stages of refinement and had been adapted to other measurement techniques by NBS and various other laboratories in the United States. Still, it was not fully appreciated as a scientific instrument because there remained a very significant problem. The high pressure group at NBS was under the ever-present prodding of management to develop a better method for measuring pressures in the DAC.
