Splitting The Second: The Story of Atomic Time (a first printing)

Until the 1950s timekeeping was based on the apparent motion of the Sun that in turn reflected the rotation of the Earth on its axis. But the Earth does not turn smoothly. By the 1940s it was clear that the length of the day fluctuated unpredictably and with it the length of the second. Astronomers wanted to redefine the second in terms of the motions of the Moon and the planets. Physicists wanted to dispense with astronomical time altogether and define the second in terms of the fundamental properties of atoms.

The physicists won. The revolution began in June 1955 with the operation of the first successful atomic clock and was complete by October 1967 when the atomic second ousted the astronomical second as the international unit of time.

Splitting the Second: The Story of Atomic Time presents the story of this revolution, explaining how atomic clocks work, how more than 200 of them are used to form the world's time, and why we need leap seconds. The book illustrates how accurate time is distributed around the world and what it is used for. It concludes with a look at the future of timekeeping.

In his book ,Jones covers the history of all aspects of timekeeping and introduces the reader to a host of related technical problems. His explanations do not involve undue technical complexity but give the reader a firm grasp of how the solutions were developed.
-Historical Electronics Museum Newsletter

... a very readable, popular account of the development of modern atomic timekeeping ... [it is] an interesting, readable account of the state of modern timekeeping ... a good introduction and well worth reading by those interested in this rather poorly documented area of modern science and technology.
-Dennis D. McCarthy (U.S. Naval Observatory, Washington D.C.), Physics Today, October 2001

With great clarity, the author describes highly technical concepts and the devices used to implement them. I would especially recommend this book to scientists and engineers who want to learn the most recent developments in this intriguing field. I would also strongly recommend the book for nontechnical individuals because it is so readable.
-William J. Klepczynski, Rittenhouse-Journal of the American Scientific Instrument Enterprise

As a lifelong student of clocks, to me this book could not have been more welcome. The book is highly technical, yet for the nonphysicist it is eminently readable. The author unravels the arcane mysteries of the structure of the atom and its particles, with readily understandable text. Throughout we are kept fully aware of the impact of this new technology on the outside world of timekeeping and measurement.
-Alan Smith, Astronomy Now, June 2001

Anyone who is intrigued by fantastic precision or curious about how we really know the time, or simply likes tales of science and technology, will enjoy Splitting the Second.
-Nature

... a splendid book for the inquiring layman, sixth-form student, and undergraduate and it's excellent value for money.
-The Observatory

... no astronomer, however amateur, should be without.
-Astronomy Now

The book will appeal to a wide range of readers from physical scientists to the man-in-the-street.
-Aslib Book Guide

A fascinating account of how time has been measured and the problems with the timekeeping methods that drove the development of better clocks .... Jones's book is a quick and interesting read. He succinctly presents physical explanations for the workings of different kinds of atomic clocks and weaves a compelling, detailed account of the difficulties of keeping accurate time.
Donavan Hall, History of Physics Newsletter, Vol. IX, No. 1

cinating account of how time has been measured and the problems with the timekeeping methods that drove the development of better clocks .... Jones's book is a quick and interesting read. He succinctly presents physical explanations for the workings of different kinds of atomic clocks and weaves a compelling, detailed account of the difficulties of keeping accurate time.
Donavan Hall, History of Physics Newsletter, Vol. IX, No. 1