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The video shows the perpetual calendar. This is a completely self-contained unit encompassing over 580 parts. The calendar is a third-order variety, taking into account leap years as well as the 100 year and 400 year exceptions to that cycle making this perpetual in perpetuity. The machine remembers the calculations needed for this ability in both forward and reverse. We believe this reversibility has never been done before in a the context of a mechanical timekeeper. ---------------------------------------------------------------------------------oOo----------------------------------------------------------------------------- Now begins the fabrication of the tellurion complication
The
model we are using for the tellurion was made by Mathias Hahn and is described in
Astronomische Uhren und Welt-Modelle der Preistermechniker im 18. Jahrhundert,
Luwig Oechslin. This is a two volume set of German-language books that contain
the descriptions of many of the world’s famous astronomical clocks and orrerys
located in Germany. There were several examples of Hahn’s work. The most
important part of this publication is the attached set of folios that show the
schematics of each item described. We chose a hand-cranked telluriom as well as
a grand orrery, both by Hahn for our components. The tellurion dates from 1780
and is in the Lindengut Museum, Winterthur, Germany. This saved countless hours
of design time if we had to design these from scratch and is another example of
our borrowing what we consider to be good ideas from the past masters in the
horological field. These were chosen at the earliest stages of the project, even before
the original wood mockup was created in 2006. On the drafting board Buchanan begins the preliminary design work. The photo on the upper left hand corner is a photo of the Hahn tellurion from the German language book. The schematic to this tellurion is in the right hand corner and comes from the same source. The center drawing is Buchanan's interpretation of this and the large diagram below is the initial scale fabrication diagram.
The photo and two diagrams are what is seen on the drafting board. Note that we have added to Hahn's design by including the inner planets of Mercury and Venus. Buchanan states "This is the first version of the tellurion, my interpretation of the Hahn to understand it and to see if we could include Mercury and Venus. I took the Pouvillon ratios from his tellurion. Now I must see if it is physically possible". Here Buchanan draws from his experience in the restoration of the Pouvillon astronomical clock he had accomplished in 2012. Pouvillon's interpretation of his tellurian was magnificent.
The first drawing shows diagrammatically all of
the necessary components to get an idea of how deep this assembly must be. It
shows that the Earth will be about 1/8 inch (less than 0.5 cm from the front
case glass.
This is a bit too close, but Buchanan indicated that the glass case can be moved
forward a bit. The issue we have is not so much that we cannot make the case
deeper, but that we do not want the front surface of the glass too far in front
of the rest of the clock mechanism; making close inspection of the remaining
movement more difficult.
The first drawing shows the over-sized idler wheels. Next several alternative sizes superimposed. This also has a side elevation represented above. The revised idler wheels are now finalized and this gives the tellurium a slimmer profile.
The first drawing depicts the central cannon tube nest. Notice the use of ball bearings which replace the conventional nested cannon tubes. One must remember that this assembly in reality is rotated ninety degrees from the drawing shown. If a conventional set of nested tubes were to be employed here, the friction would be impossible to overcome. Here is a good example of where modern design and materials make possible what would otherwise be impractical. Next color coding is added to the diagramed tellurium wheel assembly. This has been carried through the previous few drawings as well. Red = Mercury, Yellow = Venus, Green = Earth, Black = Moon, Blue = main input drive to tellurium. Not all color coded wheels of a particular color are all adjacent to each other, but may be located elsewhere and working through other wheels to their final destination.
The wheel blanks are now ready for fabrication.
If we were using modern CNC methods the data on the sheet would have been
inputted into a computer and the wheels automatically cut out. But here Deryck
scribes out each wheel by hand, as was done for centuries by the old masters of
horology and will cut them out each by hand on the jeweler’s piercing saw in the
same hand-made manner as hundreds of wheels before in this project.
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