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An Astronomical Skeleton Clock Where we stand after six and one-half years of construction Copyright 2016, Mark Frank Overview In August of 2007 the NAWCC Bulletin published the first article on a complex astronomical skeleton clock commissioned by the author and being built by Buchanan of Chelmsford, Australia.1 At that time a detailed full size wood mockup was completed and that article covered the proposed clock’s mechanical specifications and functions as depicted through the mockup. A follow up article was published in April 2011 marking roughly the halfway point in the construction. At that time the four movement trains with much of the ‘between the plates’ components were completed. These are the time, celestial, basic quarter and hour strike trains. As of July 2015 we are a decade on since the initial design and mockup and six and one-half years into construction. Right after the April 2011 Bulletin article there was a hiatus of two years during which time Buchanan had moved his shop to new quarters and taken on an intricate restoration project of another complex astronomical clock which was also the subject of a three part series in the Bulletin.2 Construction recommenced in the middle of 2013. I estimate completion sometime in 2018. In this third segment I will cover what has been accomplished since the 2011 Bulletin article. The entire left hand side of the dial complication work is complete as well as what is represented by the small dial below the large tellurian ring on the right, the strike selector, (Figure 1, prior page). The dial work is comprised of a third-order, reversible perpetual calendar. An equation of time and sidereal time functions that are overlaid by the mean solar time dial work allowing one to see the difference between all three types of time simultaneously. A small world time dial as well as the strike selector representing completion of the quarter repeat on demand in Grande Sonnerie as well as silencing. At this point one might ask, “Why is this taking so long?” I would direct the reader to the earlier two articles for a full explanation of the complexities and mechanical innovations of this clock. Very briefly we are creating a machine that will have nearly 10,000 parts; including about 400 wheels, four remontoire, dual Harrison grasshopper escapements, compound and epicyclical governor fly fans and depending on how one counts, about forty complications.3 I knew we could not create the world’s most complex skeleton clock, either in the number of complications or components. That was beyond the scope of this endeavor, although excluding institutional public and church clocks, we will probably be within the top twenty or so made that is small enough to fit comfortably within a domestic setting. My ambition is to create one of the more visually fascinating clocks. I will create a machine that will immediately grab the viewer, hold him and not let go. There have been many clocks made with a variety of visually interesting features, especially those employing automata or complex musical apparatus. This creation focuses on the visual display of an overwhelmingly interesting geared mechanism – a “gear head’s” delight. Our approach to every aspect of this machine’s creation was, ‘How can we make this part or mechanical system both beautiful and fascinating to the viewer?’ This is done through the use of multiple, complicated moving components that are actuated in frequent and in one case unpredictable ways. The other and no less compelling feature will be the beautiful design and hand crafted innovative workmanship created by the Buchanan firm which I think the reader will see, is second to none. We have also included a bit of whimsy. There is a forest of wheels within an organic ivy themed upper frame structure. And what is a forest without animals? So we have birds to inhabit the trees as well as other pa