Time's Pendulum: The Quest to Capture Time--From Sundials to Atomic Clocks

Einstein showed that time is relative on scales barely comprehensible to most of us. In her steadily engaging new book, Barnett, administrator of the Department of Microbiology at the Mount Sinai School of Medicine, shows how our notion of time is relative on a very human level. Time has undergone a long process of standardization over the centuries, she explains. When humankind used sundials, the length of an hour was relative, shorter in the winter and longer in the summer. The Christian church introduced the canonical hours to mark the times for prayers, and various guilds and professions maintained their own time systems. Early mechanical clocks still relied on sundial time because they had to be reset frequently. Thus time was not at all uniform: clocks and bells striking at different times caused such a cacophony in 14th-century Paris that Charles V ordered them all to be synchronized with one at the royal palace. The pendulum clock, with its greatly improved accuracy, put an end to the tyranny of the sun. It also allowed mariners to determine longitude aboard ship for the first time, opening the globe to exploration. The advent of the railroads forced further standardization of time for towns along the tracks, and worldwide time zones put an end to local times once and for all. Now time is measured by the vibrations of the cesium-133 atom to the subatomic degree of precision required by computer-controlled systems. Barnett's book is a triumph of interdisciplinary scholarship that could appeal to a wide variety of readers. 36 illustrations.
Copyright 1998 Reed Business Information, Inc.

Clocks have a 4000-year history, and radioactive clocks, which enable us to measure the history of the earth, are a creation of the 20th century. Barnett also explores the more philosophical question of the nature of time.
Copyright 1999 Reed Business Information, Inc.

In the numbers on our clocks, most of us see merely a summons to work, study, or sleep. Barnett sees much more: she sees the marvelous culmination of humanity's long struggle to understand and regulate the mystery of time. Starting with early farmers' intuitive reading of lengthening shadows, she recounts how mathematicians and inventors first devised ever more sophisticated sundials and waterclocks for measuring the rhythms of nature, and then--in a major conceptual breakthrough--how they transcended those natural rhythms by assembling clocks that marked out an artificially invariant cadence. But time means more than science, and Barnett attends to the cultural contexts within which human hours have been counted: the medieval devotion to God chiming through vesper bells, or the modern profit motive converting time into another commodity for sale. Balanced and intelligent, this history of timekeeping well deserves a few hours in readers' lives--and a couple of inches on library shelves. Bryce Christensen