Since the beginning of the preparation of this volume, we have been convinced that temperature and pressure measurements should not be separated, particularly in different applications at low temperatures. This belief has made us deeply conscious of the fact that the advanced applications and modern experimental methods of investigation in science and technology need the combination of various professional experiences and approaches. Although the book is divided into two parts (Part I by F. Pavese and Part II by G. F. Molinar), we have tried to correlate low-temperature and low-pressure measurements as much as possible. We hope that our readers will find this book, which contains a large number of experimental and reference data, useful in their effort to solve measurement problems. We are pleased to acknowledge our debt to several persons and wish to express our gratitude to them for their valuable cooperation and help: to our research group colleagues at the Istituto di Metrologia "G. Colonnetti" -IMGC (CNR), without whom the knowledge and the experience we built up during many years could not have been acquired; to G. T. McConville, M. Durieux, and K. Grohmann for revisions of and various suggestions for Part I; to V. E. Bean and C. R. Tilford of NIST and G. T. McConville for revisions of and various suggestions for Part II; and to I. Prinetti of IMGC for many valuable suggestions and careful textual revisions.
