Expanded, revised and updated, this detailed guide provides accurate metric equivalents and conversion factors for 10,000 scientific units with detailed descriptions of over 2000. It covers the full gamut of science, technology and medicine, and deals with US, British, conventional metric, historic and SI units. This new edition includes: new tables - presenting, for example, the detailed chronology of the definitions of the metre prototype; regional variations of old French units; the International Temperature Scale of 1990 (IPTS-1990); improved tables in Ancient Times systems of measures; additions to the A-Z listing of units - such as the G unit for the radiochemical yield either in the cgs or the SI systems; several units of turbidity; the pH definition; and an updated listing of numerous US professional societies, with at least 20 new entries added to the list. The pocket-sized format and slot-in user guide bookmark make the book user-friendly, and renders the extraction of relevant information as simple as possible.