Customer Reviews

Time's Pendulum: From Sundials to Atomic Clocks, the Fascinating History of Timekeeping and How Our Discoveries Changed the World

5 star:		(4)
4 star:		(3)
3 star:		(1)
2 star:		(0)
1 star:		(0)

 

 

This is really two books--the first is a chronological history of time measurement devices, and the second is a history of humankind's perception of the age of humanity, the earth, and the universe. The first book is fascinating and well written. Writing for a general readership, Barnett explores the development of clockmaking and how the existence of ever more accurate clocks has irrevocably changed everyday life for us all. Her detailed explanation of the verge-and-foliot escapement was especially fascinating, as was her discussion of "the equation of time" and how it gives rise to the Mean in Greenwich Mean Time. Overall, the first half of her book is a wonderful introduction to an underappreciated portion of humanity's history. The second half of Barnett's book, however, is a rehash of material that Isaac Asimov explored fully in his nonfiction writings in the 1960s and 1970s. It may hold the interest of readers unfamiliar with Asimov, but for me it was a real disappointment, especially after such a compelling introduction to the history of clocks and clockmaking.

Jo Ellen Barnett has written two books here, hidden between one set of covers. The first part goes over the history of how we have measured (and, truly, how we have defined) the time of day, starting with the "temporary hours" of a sundial (longer in summer, shorter in winter, and not even counted during the night), and transitioning to equal (but still based on the sun) hours (local apparent time), then to local mean time, to standard (time-zone) time, and ending up with the current Coordinated Universal Time, based on atomic phenomena. The story is absorbing and well written, and would be an enjoyable book all by itself.

Then she has a second part, concerned with the way we have determined the age of the earth. This could be said to start with the speculations of the Babylonians and Greeks, but really took off in earnest with medievals' attempts to build everything on a Biblical basis, reading into the Biblical account whatever they needed to build their chronology. When the geologists tried to account for their own observations, however, it was clear that the few thousand years the Bible literalists derived for the age of the earth was far too small, but physicists like Lord Kelvin (while arriving at a longer time than the Bible provided) still reached an age of the earth too brief to mesh with the geological evidence. Only with the discovery of radioasctivity and the refinement of the techniques of deriving chronological data from radioactivity measurements could the physicists and geologists be reconciled.

Both parts make it clear that ultimately time has become defined in terms of atomic phenomena (though different parts of the atom) and only through our measurement of these can accuracy be attained (whether in the case of the time of day or the time the earth has taken to evolve since its origin).

Unlike some other two-part books I have reviewed, this one puts them both together successfully. It is a very interesting book.

Time's Pendulum is a book not only about time and how time is measured, but also about our perception of time -- from the moment we as a species started worrying about it right up to today. Barnett does not only discuss clocks and how clocks work but the importance of time in daily life. Also excellent is her discussion of 'deep time' -- thinking about time on astronomical scales. I was also pleased by the more subtle connections. For example, the influence of the railroads on not only synchronizing watches over extending longitutes (i.e., time zones), but also their contribution to geologic time through uncovering the fossiliferous rocks during their construction.

How many times a day do we unconsciously look at our watches, or the clock on the stove or the VCR (provided it's not permanently blinking 12:00)? Yet for many years, the capture of time to a clock was at best around the right hour of the day. Bernett takes us through the refinement of clock technology and clock making, and how this more exact time changed our lives, some would argue with the idea of a change for the better. She takes us on a simple and entertaining sweep of time from sundials to measuring the beats of an atom in order to tell what time it really is. Along the way there are arguments about the prime meridian and time zones as we are forced to go from telling time by the sun above each of us, to entire time zones on a single time, irregardless of where the sun exactly is. At least the trains could run on time.

Then Barnett pulls back and looks at the greatest clock around - the planet Earth itself. The question of how old the Earth is was a question that kept pushing the answer back and back further in time. Of course the Earth was only 6,000 years old, according to biblical interpreters. That is until the strata and fossils began to be understood, and then half life of radioactive elements could fix time ever more exactly. Now that we are able to "read" a good part of the clock that is the Earth, our placement of ourselves in time has also settled. So now we have a concept of where we are in time, and how to find it. At least until the earth slows some more due to friction in the tides. An interesting book that doesn't delve too deep and pulls you along on an interesting, everyday subject.

I agree with the Gibson review below ("Two books in one, both interesting!") and can little to it.

I wish the author would come out with a update version with pictures and more diagrams.

It is not the kind of book that traps you until you finish it, but so far I have enjoyed it.

Fantastically researched and written. Highly, highly recommended, but be warned - you will want to read it twice!

I've already had some interest in the topic, but wanted to pickup another book and see what else I could learn, so got this one based on the reviews. A very good book, would highly recommend for someone who wants to learn about the history of keeping time.