BOOKREVIEW: Roberts: Precision Pendulum Clocks Trilogy

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Fortunat Mueller-Maerki

NAWCC Star Fellow
NAWCC Life Member
NAWCC Fellow
Sep 23, 2001
Precision Pendulum Clocks,
A Trilogy of Books by Derek Roberts.

Precision Pendulum Clocks – The Quest for Accurate Timekeeping
ISBN 0-7643-1636-2, 224 pages

English Precision Pendulum Clocks
ISBN 0-7643-1846-2, 296 pages

Precision Pendulum Clocks – France, Germany, America, and Recent Advancements
ISBN 0-7643-2021-1, 288 pages

Schiffer Publishing, Atglen PA, published 2003 to 2004, each volume richly illustrated (mostly in color, 24x31 cm, Glossary, and Index in each book, and numerous bibliographic references in each chapter. Hardcover, dustjacket. Purchase for ca. $80 each, e.g. at Lending copies of all three volumes are also available to NAWCC members at the Library and Research Center in Columbia, PA.

Notwithstanding the review I wrote for the first book in this series when it was first published in 2003, the overall importance of this trilogy on the precision pendulum demands and deserves a comprehensive review of the whole work. The three books, even if published separately due to commercial and marketing considerations, clearly are (and were written as) one three volume piece.

Enthusiasts of precision pendulum clocks have not been spoiled by much available literature on the subject prior to this opus magnum by Roberts. The only other comprehensive modern book on the subject dates back over a quarter century, and is in German (Erbrich, Präzisionspenduluhren, Callwey, 1978, 3 7667 0429 X). Precision pendulum freaks from the Horological Science Chapter of NAWCC, who don’t read German, had become so desperate for information that they banded together and collaboratively typed much of the Erbrich text into computer driven translation software, thus clandestinely producing a translation in Pidgin English. Another recent title (Matthys, Accurate Clock Pendulums, Oxford University Press, 2004, ISBN 0 19 852971 6) is a wonderful addition to the literature, but is not suitable for the general reader, being a highly technical treatise on the physics, mathematics and materials of the timekeeping pendulum, rather than a discussion of clocks.

The subtitle of Roberts’s first volume “The Quest for Accurate Timekeeping” neatly sums up the very essence, the raison d’être, for the art and science of mechanical timekeeping through the ages. Given the central importance of the subject to horologists, it is hard to understand why more has not been published on precision horology. The key reason may well be that the most accurate timekeepers of each era were always very rare, they were always scientific instruments meant for observatories rather than timekeepers for the general public. Few horologists have seen a representative sample of such clocks across centuries and geography, let alone had a chance to examine and document them in detail.

Derek Roberts, who for most of his life ran a retailing establishment for high-grade clocks in the United Kingdom, not only had a lifelong passion for the subject, but over the decades also had the opportunity to record and document many of these one-of-a-kind objects. I would estimate that over 500 of them are shown or mentioned in this publication.

The bulk of the first book really sets the stage for a most comprehensive treatment of the overall subject. Various chapters deal with the fundamentals, such as the astronomical base of precise timekeeping, sidereal vs. solar time, the equation of time and mean time, zone time vs. local time, etc. as well as physics and engineering constraints, such as pendulum isochronism, temperature and barometric compensation, escapements and electric clocks. Far from being dry theory, all these subjects are explained with numerous examples and countless illustrations. In the compensation chapter alone I count 83 illustrations, dealing with 47 different clocks.

Though physically part of the first book (presumably they are there to even out the bulk of the three volumes) the chapters on Tompion, Graham and Harrison thematically belong into volume two, which chronicles British efforts to build accurate clocks over 150 years. Separate chapters are devoted to the leading horological dynasties such as Arnold, Dent, Vuillamy or Fordsham, while other, less prolific, but nevertheless prominent makers (such as Mudge and Dutton, Ellicot and Cumming, Earnshaw and Margetts, Hardy and Reid) are paired into chapters, while less important makers are grouped based mainly on chronology into the four remaining chapters. In these 15 chapters on English precision clocks the author is at his best, drawing on his encyclopedic knowledge of the subject, and benefiting from his hands-on access to innumerable examples both in the public and private realm. While the relatively spare text in these chapters is certainly also worth reading, the biggest value to this reviewer lies in the extensive illustrations and their detailed captions. The typical clock listed will average three pictures, the majority of them being large scale, detailed color photographs taken by the author, showing both cases and movements, as well as often several technical details in close-up. It is refreshing to this reviewer that the author’s photos were carefully taken to show off some technical nuance, rather than focusing on conventional aesthetics. Often, these photographs are augmented by reproductions of technical drawings – many of them contemporary to the clocks or by the hand of the builder – explaining the defining feature of the particular timepiece. While, of course, images can never replace examining the physical artifact, in this case the quality of the pictures assures that you may learn more from studying them, than by observing the clock through the glass of a museum showcase.

The third book covers precision pendulum clocks produced in France (9 chapters), Germany (3 chapters) and the USA (1 chapter), as well as three chapters dedicated to 20th century examples (primarily the Russian Fedchenko clocks and the Littlemore clock by Teddy Hall).

Roberts did not attempt to write the entire text himself; actually 4 of the 10 chapters in the first book, and 4 of the 16 chapters in the third book, appear under the byline of eminent experts in their specialized fields (Jonathan Betts on Astronomy and Precision Time; John Martin on Escapements; Denys Vaughn on Electric Clocks, and A.D. Stewart provides a 200 year timeline style summary of the subject, while Donald Saff wrote the Chapter in American Precision Pendulum Clocks (including Fasoldt and Bond), and the three chapters on the 20th century were contributed by George Feinstein, E.T. Hall and Philip Woodward. By focusing on the introductory chapters and describing the developments in England and France the main author focuses on his own area of expertise.

Taken in its entirety, this trilogy is clearly the currently defining publication on the subject “Precision Pendulum Clocks”, and is likely to remain such for a long time. Not only the precision timekeeping enthusiasts, but any serious student of horology, owes Derek Roberts thanks for having created a publication that is destined to become the standard reference on the subject.

Compared with that achievement, criticizing some specific details seems petty. This reader would personally always favor another technical diagram of an unusual movement feature over an image of a dial or case, but realizes that marketing realities demand a certain number of “pretty” pictures, in order to prevent a book from being thought of as “for technical horologists” only. It sure would have been nice to have a comprehensive, cumulative index covering the three volumes together. Furthermore, it soon becomes clear to the reader that abandoning the original “one-title, three volumes” concept must have come late in the production. This resulted, in at least one instance in the first book, where the reader is referred to chapter 28 for further information. But book one has but 10 chapters and each book starts renumbering its chapters with “1”.To this reviewer, such an oversight in the final editing, while slightly annoying, only underscores that -despite claims of the publisher to the contrary- this trilogy should be considered one major literary horological work.

The book is well suited to appeal to various types of readers: On one level, it is an enjoyable “coffee table” book with many pretty pictures of superb, world-class clocks, as well as interesting tid-bits of technical knowledge to be learned by the casual, unsystematic browser. Unlike most books appealing also to the superficial reader, Roberts, however, also succeeds in producing a scholarly text that stands up to highest scrutiny for the scholar who is eager to read every caption and pursue every footnote. The references to sources and further bibliographic resources (grouped at the end of every chapter) are voluminous; the compensated pendulum chapter alone lists 32 publications providing leads for additional study.

Derek Roberts’ trilogy on the “Precision Pendulum Clock” deserves becoming the standard text on the subject, and should be part of any well rounded horological reference library.

Fortunat F. Mueller-Maerki, Sussex, New Jersey
October 2006

Jeff Salmon

Registered User
Apr 11, 2002
REVIEW: Roberts: Precision Pendulum Clocks (The "Trilogy")

I really enjoy this suite of books. I was surprised that there was no treatment of Hezekiah Conant and his Isochronal Pendulum clock. the photo and description in the Time Museum catalog, part 2, is really fascinating.


Registered User
Jun 1, 2006
REVIEW: Roberts: Precision Pendulum Clocks (The "Trilogy")

I would love this set and you guys over there look to be doing a lot better on the price! From a quick look Derek Robert's own site has them at about the same price as amazon in the UK at ca £60 for vol 1, vol 2 & 3 are both £80, Amazon of course is free postage but doesn't seem to carry vol 3.

Now who can I ask to buy me one of these for Xmas. :rolleyes:
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NAWCC Member
Jan 22, 2002
REVIEW: Roberts: Precision Pendulum Clocks (The "Trilogy")

They have them on eBay all the time. Maybe you can cut a deal with a seller for the 3 of them. If you have them shipped surface mail, I would guess around 20 pounds or so. About double by air parcel.

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