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Restore Easter calculator weight and chain, create orrery planet counterbalances; MECHANICAL RESTORATION COMPLETE

The Easter calculator is a self-contained mechanism and has its own separate weight which runs the calculator when actuated by the clock once per year. The weight cord was missing when we received the clock and a close examination of the weight drum and the associated pulleys showed a square cross section. This is in contrast to the normal rounded 'U' shaped cross section one would expect with a cord, gut or other conventional round cross section weight line. Small, regular indentations, more like 'teeth marks' were also seen on the drum as well as the fact that the attachment point on the drum requires a chain hook. These observations indicated that a fusee type watch chain was originally used to attach the weight to the calculator.

The total length of chain needed was close to 20", (51cm), a bit longer than a typical watch fusee chain. I had purchased a package of chain on-line and Buchanan used these to create the length needed.

Several sections as received were either too rusty or otherwise unacceptable and were removed. The balance of the chain was then rejoined.


The completed chain is finished. Next the completed length was then tested for strength.

The original weight was missing and so a new weight had to be made and was done in the same style as the clock's main weights. A rectangular block made of cast iron 2.25" x 1.78" x 15/16". The third photo shows the weight strung within the wood cabinet base. It would have been more visually interesting if Pouvillon had somehow made the weight to appear outside the cabinet so one could see it fall as the calculator operated. However, the size of the weight as well as the amount of drop needed made this impractical.

The first photo shows the chain wound onto the barrel. The next two show the pulley set used to direct the chain from the drum to a hole located directly below the outboard pulley where it enters the base cabinet.

We now deal with the open support areas that are on each of the collets which support the planets within the tellurian (Mercury and Venus) as well as the outer planets on the orrery (Mars, Jupiter, Saturn Uranus, Neptune and Pluto), It appears Pouvillon as late as the 1950's had not assigned a purpose for these additional mounting points that are located 1800 opposite of each attachment point for the eight planets (Earth excluded). So why did he create these structures? Perhaps he thought that a counterweight would be necessary for the planets and later figured out that it was not necessary. What remains a mystery is why, if this were so he would not have taken the simple procedure to shave off these points. They are so prominent as to be a real distraction, and this is especially true for the two inner planets, and begging the observer to ask "what is supposed to be attached here?"

We now enter an area where the preservationists camp will raise serious objections. We have no information at this point what purpose Pouvillon had for these mounting points. A counter balance seems to be the obvious answer. So we decided to fill this mounting point with what could be considered a counterbalance but also add some additional information in the form of making that counterbalance into a sign of the zodiac for each planet to which it is connected. At any rate these wires are easily removed if in the future one wished to do so.


As received the clock was missing all of its planets and anything that might have been in the places opposite the mounting points for each planetary collet. The second photo is a close up of the collet nest. Here the planet wires that hold each of the six outer planets are present. However, the mounting areas directly opposite each of these are empty.


The first photo is from the 1950's showing Pouvillon with his clock. One can see first that each planet was mounted on a wire with a single 900 bend. A careful examination of the area of the photo that shows the collet nest used to hold the six outer planets reveals that the opposite mounting points are empty. So at this late date Pouvillon had not seen fit to use what once was clearly something he had plans for. This photo however does give us a good indication of the size, spacing and color of the planets. The next photo shows what was done in 1983, presumably by the Paris clock dealer Jean-Pierre Rochefort to resolve this problem. This photo is from an advertisement he had placed in the Antiquarian Horological Journal at the time. Here he simply duplicates the planets doubling the number from eight to sixteen (four for the inner planets and twelve for the outer planets). It also appears that he had the hemisphere of each planet painted white and black. It is impossible to ascertain if Pouvillon had done this for any of the planets other than, of course the Moon.


As received, the two inner planets and the six outer planets were missing along with their mounting wires. From the photo we have of Pouvillon we knew how to recreate the planets has he had originally intended. However, what do we do about those empty mounting points? Since the decision was made to utilize these, the question became "in what manner?" I rejected outright Rochefort's option. It seemed to me artificial and completely confuses the viewer as to the correct position of the planets. The first illustration, and we only deal with the outer planets in these, shows an option where we substitute the duplicate planets with zodiac indicators for each planet, but basically keeping with the same design as initiated by Jean-Perrie Rochefort. This would have been little better than Rochefort's design as to the clutter added to the orrery. A second option was to lower the zodiac indicators to the level of the zodiacal ring. I considered this because I wanted to use the ring as a reference point for the planets. However this option was rejected because the indicators would be too far from the ring to be of any use.


One way to make the indicators very useful would have been to alter the design of having each planet connect to the collet nest by a single 900 bend and substitute three such bends as shown in the first illustration. A close indicator pointer would have been ideally positioned near the ring. Of course this would have resulted in a major change from what we know Pouvillon had designed for the orrery and so this was rejected. The next illustration shows the solution I decided upon which was to have each zodiac indicator mounted to a horizontal wire, and laying flat in the horizontal plane. In effect, pancaked above each other as illustrated by the small green lines. In this way we avoid the clutter of Rochefort's option and we use the empty mounting points with on option that utilizes the information on the zodiacal ring to plot the position accurately with the zodiac, albeit at 1800 opposite to each planet. These can also be considered as counterweights. I think the video below will reveal this as the best option.

 This completes the restoration of the mechanical components of the Pouvillon astronomical clock. It is now completely functional and all of the original and missing components and  functions are complete and operational. The remaining issues are non-mechanical in nature and will be described in a later chapter.

The video below shows a demonstration of the orrery showing the planetary zodiac signs positioned near the lower zodiac band. Observe how these make reading the position of the planet very easy in relation to the band as well allowing the viewer to know where a planet is in each zodiacal house as well as showing when the planets are in conjunction. Note that the Earth /moon system is not in motion during the demonstration as one would expect. This is because those are driven by the time train while the balance is driven by the strike train. It would have been very difficult for Pouvillon to have merged these two separate systems for the purposes of a demonstration. For those who cannot use the built-in viewer on the left, please click on the YouTube video to the right.




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