REVIEW: Hoppes: Most Important Clock in America. The David Rittenhouse Drexel Clock

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Fortunat Mueller-Maerki

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Sep 23, 2001
[COLOR="Red"[B]]A Complicated Clock Described[/B][/COLOR]
The Most Important Clock in America. The David Rittenhouse Astronomical Musical Clock at Drexel University, By Ronald R. Hoppes (Text), Bruce Forman (Conservator, Gear counts and Photography). Published 2009 by the American Philosophical Society, Philadelphia (as Transactions of the American Philosophical Society, Volume 99, Part 2). ISBN 978-1-60618-992-4, ISSN: 0065-9746. 99 pages, 25 x 17 cm, 75 illustrations, some in color. Index. Includes a Biography of Rittenhouse by Jacqueline deGroff. Available from for US$35, or borrow from the National Watch and Clock Library, Columbia PA.

Monographs documenting a single timepiece are among my favorite horological publications. If well done they allow the reader to ‘explore and discover’ in some detail a clock that s/he may never get to examine closely, or even one they never get to see. When the clock in question claims a superlative label, like ‘The most important clock in America’ I get curious.

To answer the obvious question first: Is the clock that David Rittenhouse built around 1773 for Joseph Potts the “most important clock [made] in America”? Well, that is an opinion on which there can be disagreement rather than a fact, but I would agree that this clock is one of the most likely nominees for that honor. David Rittenhouse (1732-1796) of Philadelphia undoubtedly was the most talented clockmaker in the pre-revolution American colonies, and the only one who designed novel astronomical gear trains of his own invention. He built both precision clocks for surveying and for astronomical observatories, as well as a few showcase tall case clocks with complex astronomical indications. Three of the latter have survived and the one currently on display (by appointment only) at the Picture Gallery of Drexel University in Philadelphia is grander, technically more innovative, and less modified than the two others (who are in a private collection and at the Philadelphia Hospital respectively). It is also one of only two 19th century American clocks that has the equation of time and a full orrey and plays multiple tunes on a full set of bells. (The other is John Elicot’s Clock No. 32, the four-sided clock made in 1769, which is probably the closest contender for the honor of ‘most important’) That makes it hard to argue against the superlative claim in the title of this book.

The publishing history of this text is somewhat complicated. A very similar publication was published in 2008 in a private limited and numbered edition by the primary author, Ronald Hoppes, who is the current caretaker of the clock, utilizing the photographs and gear-counts of Bruce Forman, which were taken in 2005 and 2006 when Forman worked on it for over a year to get it into running condition again after it had been dormant for decades. (Incidentally, a short report on that restoration by Forman has been published as a small, free brochure by the Drexel Collection, and anybody interested in that story may obtain it from Drexel). Given that David Rittenhouse was President of the American Philosophical Society (a Philadelphia based institution founded in 1743 by Benjamin Franklin, and the oldest ‘Learned Society’ in the US) it is not surprising that the Society agreed to give the text a wider exposure, republishing it in slightly modified form as Volume 99, Part 2 of their serial ‘Transactions of the American Philosophical Society Held in Philadelphia For Promoting Useful Knowledge’. That format assured that the text is now in most major academic libraries.

The book opens with a short biography of Rittenhouse by Jacqueline DeGroff, the Curator of the Drexel Collection, but the bulk of the book is a detailed technical description of the mechanism of the clock. A ten-page section describes the functions of the various dials. This is complemented by numerous illustrations, both color photographs and black and white diagrams. These images are very helpful, but this reviewer is most disappointed that their quality is not better, and does not do justice to the quality of the clock. Apparently, these photos were originally taken by Foreman to document the 2005/2006 restoration, and their reuse for a publication was an afterthought.

The center section, some 70 pages, is devoted to a description and analysis of the various gear trains, including the time train, the lunar train, the calendar train (driving a large disc revolving 365 ¼ days), the orrey train, the equation of time train, and the musical train. In all cases the actual teeth-counts are provided, in addition to the revolution speeds of the arbors. All of these are also illustrated both by photographs and schematic diagrams. For those readers interested in the gearing details it is noteworthy that Rittenhouse achieved approximations to the real astronomical ratios that exceeded those used by most of his contemporaries. The solution he chose to represent the equation of time, i.e. the variance of local solar time from mean time, is based on two epicyclical gear trains representing the two elements of the equation of time, and then adding those two components together (rather than using the traditional ‘kidney cam’, which is a graphic representation of the already added two elements). The final chapter describes the procedure for setting up the astronomical dials.

Documenting any clock of this complexity is a formidable challenge, and I want to compliment Hoppes and Forman for getting this information into print. None of the other complex astronomical mechanisms of Rittenhouse are documented to that extent, so this represents a major addition to horological scholarship. But at the same time, I am quite disappointed about the missed opportunity to create a text that does more than document the gear counts. The most blatant shortcoming is that the publication under review completely fails to discuss the case of the clock, which is a significant and major piece in its own right. Furthermore, to do full justice to this masterpiece there is an urgent need to also put both the mechanism and its creator into a historic context.

Let us hope that the Hoppes book ‘paved the way’, and inspires another author to work on a more comprehensive publication on the horological achievements of David Rittenhouse, the amazing genius and self-taught Renaissance man of the American revolutionary period. It is a story that deserves to be told.

Fortunat Mueller-Maerki, Sussex NJ September 2010
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