This book more clearly belongs on the science bookshelf than do most which deal with measurement, a reflection not of its relative quality--although it is a fine book--but of the fact that others get so involved with numbers and scales and the rationale for standardized measures that little time is left to explore the scientific uses of measurement. Here the organization is around areas such as sound, electricity and magnetism, light and radiation, though there are chapters on such standard topics as mass, length and time. Each unit is treated historically, length moving from the Biblical cubit through establishing the wavelength of Krypton 86 emission as a standard and on to today's use of laser interference to set unit lengths. Thus a great deal of scientific development in the fields is covered in exploring the changing nature of measuring. In contrast, a more common approach such as Carona's (in Things That Measure) offers simply a historical outline of devices.