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Fabrication of annual step wheel and cam pack blanks. Begin disassembly of mystery dial.

At this point we begin to restore and replace parts that were missing from the clock as received. Here is where the inevitable conflict between preservation, conservation and restoration collide. A decision has to be made. Do we side with strict preservation and conservation? If so the clock will never fully function as it cannot without its full compliment of parts. Do we destroy or obscure the original by creating missing parts? As one person commented, sic. "It's like painting over prior picture." What if the picture is torn, does the museum not mend it? These questions are rarely an all or nothing issue. It all goes down the road of degree. The steps below outline how we have chosen to approach the issue on this significant horological object.

1. We will endeavor to make the clock completely functional through the repair of current or replacement of missing parts. 
2. All replaced parts are made in the manner we can best determine to be as close to the original as possible using existing witness marks on the movement as well as any historical documentation we can uncover. We will also make these parts look as close in style and age as they might originally. This second statement will raise eyebrows in some quarters where it is strongly felt that any replaced parts should be made in such a way as to be immediately identifiable as such. This may be an option in a cased clock; where the movement is out of sight. But here it is in plain view and is the center of attention. It would be analogous to replacing missing veneer or case moldings on a rare tall case clock with exact fitting brown plastic parts. While the pieces may fit perfectly, it is not suitable to do so. We are hiding nothing as the entire process is open and for all to see on this website. 
3. Under no circumstances is there to be any alteration to any existing piece of the clock. No parts are to be altered, holes drilled, or components moved to accommodate the new parts. All of our efforts are fully reversible.

To me the beauty and significance of this clock lay not only in its unique design and its embrace of the complexity of the levers and wheels trains contained within, but its ability to fascinate and inform the observer through its operations. To me  restoring this movement means bringing it back to its full awakening to new life. Without the restoration of the missing parts it would still be a valuable horological artifact. But its soul would be absent like a stuffed bird on the wall compared to others on the wing.

I have asked Buchanan to provide what I call a 'forensic' report. That is to record his observations as he goes along. I will provide the .MP3 audio file for each segment but just in case your security settings will not allow you to open this file I have also transcribed each session. My additional comments will be inserted into the text from time to time and this will be in red text. Buchanan refers to each photo by the number of that photo which can be followed by each photo above the captioned text. The .mp3 audio file will appear at the beginning of the photo sequence in blue text. Click on this text and you can then follow along with the audio file by scrolling downward through the photos as they are narrated one by one in the voice of the restorer.


The first photo shows the initial fly cutting of the index wheel. The second photo shows the index wheel fitted to existing pawl designed to hold the wheel stationary until the next fifth day feed. The last three photos show the assembly mounted within the existing clock’s structure. It fits neatly between the two drop down frames. The five cams which control nearly the entire left hand wall of the clock as well as the mystery dial are mounted to this arbor. The wheel has 73 teeth and is driven once every five days for one revolution in 365 days, (73 x 5 = 365). This wheel is the drive for the cam pack that will be attached to the arbor.

Pouvillon-21-001.MP3. Photo 21 002. This is the operating mechanism for the sunrise/sunset dial. The two black levers horizontally in the photograph are the teeter-totter levers. The point of this photograph is to show at the right hand end of these two levers we can see the bluing has been rubbed off by the operating cams (witness marks). And it also gives us the position of the cams on the missing one year arbor (the arbor that will hold the cam pack assembly). Interesting to note is the little counterbalance weight on the length of day and length of night lever. The round rod in the center, it has been plated but the radius on each end have obviously machined away the plating. Photo 21 005. This is another view of the teeter-totter mechanism for the sunrise/sunset shutters. What we’re trying to show in this photograph are the four pins roughly in the center of the photo with the ridge in the middle which are, I believe, spring anchorage points to maintain contact between the lever and the cams that are missing. Photo 21 006. These are the four cam blanks. They are discolored due to annealing, as they, obviously, will be fairly delicate items by the time they are finished and in the foreground is the lever mechanism, for the day/night length and sunrise/sunset shutters. These cams will later hardened before installation.

Photo 21 008. Here we have a view from the front of the clock just below the orrery platform. And I’m trying to measure the gap between the lever for the sunrise/sunset shutter which you can see on the left hand side of the picture and the one year arbor to establish the maximum diameter for the operating cam. Photo 21 009. This is obviously the front view of the mystery dial for the equation of time. Of interest to note which I will point out again in later photographs is the central decoration pattern in the center of the dial which serves to hide the extremely small 12:1 ratio gear box. If you look very carefully at the 35-40 minute position you can just see a few teeth of the 12:1 motion work projecting just outside of the pattern in the center of the dial. These discs are plastic. We later determined them to be glass. The question has been raised as to whether this is also an add-on as the tellurian or whether this is a full-on Pouvillon complication. And at present my opinion is most of this is Pouvillon original, although as we progress in the photos, there are certain components, I believe, he has borrowed from pocket watches. The surround to the dial, the engraving is very typical of engraving on other parts of the clock. This leads me to believe that it is Pouvillon work. Photo 21 010. This is the center of the picture, is the star wheel that revolves once a year obviously still to be spoked in the distinctive pattern that we can see in the one photograph of the clock in its original form. This is a blow up  from the first photo in the Miclet article. 


Photo 21 011. This is the upper surface of the orrery support plate. It is, if fact, mostly covered by the actual base plate for the orrery itself. Of interest to note is that there are a number of screws projecting though the plate and also the cutouts clear projections below the main orrery plate. We can also see a stoned finish on this plate and I’m wondering whether it would be in order to maintain this finish as an original finish as opposed to other surfaces which are completely polished. Photo 21 014. This is a back view of the mystery dial; the equation of time dial. The ring that retains the plastic centers is not plated while the rest of the construction all appears to be gilded. You can see in the center of the rear stationary plastic disc the support pivot for the mystery dial as well as vertically above it just projecting from the rim we can just see the extremely small 12:1 motion work.

Pouvillon-21-014.MP3. Photo 21 015. We have the support tube removed from the main mystery dial. Photo 21 016. Of interest are the cut off screws without finished ends on the end of the support bracket. And also a little bit of bad finishing work on the actual flange itself on the left hand corner. Photo 21 017 is a view from below showing the drive mechanism to the mystery dial we have an arbor cross-wise in the hole. From the left hand side is a bevel gear. The black dot in the center is the pivot for the driving bevel, obviously, which is removed. And on the right hand side is the gear that drives a very small pinion further inside the mechanism.

Photo 21 018 is a close up of the 12:1 ratio gear just visible in the center. As I’ve said before an extremely fine gear for something of this size. We can also see deterioration of the printing of the hand on the plastic dial this is going to be a conservation problem. Photo 21 019. We have the plastic disc that drives the hand and its driving gear at the bottom of the picture. And in the front of it we can see the six toothed pinion that is driven from inside the base. Photo 21 020. We have the rear support plate or the back plate of the mystery dial removed and we can see the driven gear and the driver gear below. Also of interest to note are the center punch marks on the plate.

Photo 21 021. We have the little front plate removed and we can see more of the driving mechanism. Photo 21 022. A closer picture of the bridge supporting the drive arbor. Photo 21 023. A close up of the gear and pinion that actually drives the mystery dial. Both the larger gear and the pinion appear to be modified pocket watch components.

Photo 21 024. Another view of the driving gear and pinion. And we have a little brass bush just visible between the gear and the actual pinion which leads me to believe that this was a pocket watch winding gear added to a pocket watch pinion and the brass bush is an adaptor to make the two together into one component. It wouldn’t be normal pocket watch construction or if one were making this component from scratch for one’s self, the pinion would be made a press-fit into the gear as on most pocket watches. Here we begin to see the small handful of components Pouvillon used from other sources to build the mystery dial internal components. Photo 21 025. The intermediate drive gear and arbor removed from the mystery dial. We see a bevel wheel drive which appears to be very similar to a pocket watch winding gear or winding bevel. And also, I believe, an adaptor collet at the back with a very standard Pouvillon style of grub screw to lock it onto this arbor. This is required because unless one has the bevel gear separate from this arbor you can’t remove the arbor from the little bridge plate. Pouvillon-21-025.MP3. Photo 21 026. We have another view of the intermediate drive arbor and the bevel with the brass bush and the grub screw that I believe is a modification.

Photo 21 027. A front view of the intermediate arbor and showing the gear wheel which I believe is borrowed from a pocket watch or cannibalized. It doesn’t bear the standard Pouvillon stamp (style) and appears very much to be very much a standard pocket watch component. Photo 21 029. We have a view from the other side of the intermediate gear showing again what I believe to be typical pocket watch style where we have small bevels on the spokes also the riveting; not common to other components in the Pouvillon clock. Photo 21 030. Here I have the complete drive train to the mystery dial assembled without any external components. So we have the glass tube that would come from the main time drive with the little bevel cemented into the tube; driving below it the bevel on the intermediate arbor. Then we have the brass gear in the foreground meshing with the little six tooth pinion in the actual bezel of the mystery dial and that itself again driving the larger steel gear which drives on the rim of the mystery dial. The gearing is arranged so that one revolution of the glass tube gives us one hour or one revolution of the driven disk in the mystery dial (upon which is mounted the minute hand).

Photo 21 031. Just a close up of the bevel gear drive using, I believe, winding bevels from a pocket watch. This is also substantiated by the fact that we have a compound bevel gear. Where we have a bevel with a cylindrical gear machined out of one which performs in a pocket watch two functions. And here it is used only in a single function. The compound bevel gear has a specially designed tooth profile that allows it to properly mesh as a bevel gear set and to be able to drive a wheel with a normal toothed profile. This arrangement would commonly be found the winding stem in a pocket watch where the stem is at a 900 angle to the plane of the watch train and so is geared through a bevel gear set to transfer the feed from the stem to the watch. At this point a conventionally toothed wheel carries the feed to wind the mainspring. Photo 21 033. A close up view of a screw that attaches a bridge inside the mystery dial. It appears to be borrowed from a watch, not one of Pouvillon’s standard type screws. Again reinforcing a little the fact that he was using components that came to hand whenever possible or whenever it suited him. We will see as we go along that Pouvillon’s use of other parts is fairly limited, with the exception of the tellurian. They are largely confined within the mystery dial. In this component we have some of the smallest wheels and other components that will be encountered in the clock and it is possible that Pouvillon was equipped to make parts on the scale of a clock, but not a watch. Or he was simply opportunistic and took these small and unobtrusive parts wherever they served satisfactorily to save time and effort.

The remaining four photos show the step wheel and the four blank cams, (the cam pack), installed into the movement. You can see there is a bit of room still open on the left end of the arbor. There is yet to be one more cam to be fitted in this area in connection with the Easter calculator. The cam pack is the one major component that was lost on the clock quite early on after the death of Mr. Pouvillon in 1969 since we know from other photos taken in 1983 that this component was already missing.

Pouvillon-22-004.MP3. Photo 23 001. He we are marking out the one year wheel for the equation of time cam arbor. As you can see we have a steel movable bar which we can adjust the inner and outer center to obtain any thickness or taper of spoke. And you can see the little arrow-shaped clamp in the vertical slot in the jig plate which serves to clamp any wheel that we want to work on. Photo 23 002. Here we have the marking out of the year step-feed wheel practically complete and the holes drilled for the piercing saw blade to enter in each section. Photo 23 003. As you can see the piercing of the gear blank is in process. We have an extra brass disc with a narrow slot below the blade to prevent distortion which occurs if you use a support disc with too large a gap. If the tooth of the saw catches an unsupported spoke and here we’re working with spokes less than a millimeter wide and the stock is only about 1.1 millimeters thick. It can quite easily badly distort the spoke if the blade catches it at all.

Photo 23 004. Just a slightly enlarged view of the Hegner scroll saw I use as well as the binocular microscope which facilitates cutting accurately to the line. Photo 23 007. Here we have the completely pierced wheel and all the waste that came out of it. Photo 23 009. The completed wheel on its arbor the spokes have been filed. We have introduced a little taper to the parallel spokes as when finally cut out the spokes, each individual spoke, was parallel and they looked heavy towards the end so we introduced the taper to give a more balanced look. It is impossible to know if Pouvillon had introduced this refinement in his original step wheel because the old black and white photo from which we took the design from does not have the resolution to determine this. However this is quite possible as it is quite likely Pouvillon drew the inspiration for this wheel design from prior makers. An example from an orrery clock by Zacharie Raingo, c. 1810 is shown below. This example has a bit more of a taper to its spokes.



Photo 23 010 is the one year arbor fitted below the orrery platform with the one year drive wheel mounted and the four cam blanks. The smallest is for the length of day length of night indicator mechanism. The next two, equal sized, are for the sunrise/sunset dials (actually the shutters not a dial) and the fourth one, you will see we already have reduced the thickness from 1.6mm to 1.2mm is for the equation of time dial. This cam had to be thinned in order to fit between the two guide whiskers present on the equation cam following lever. Photo 23 011. We have a full front on view of the four cams on the one year arbor. In the upper left of the photograph we can see the two blued levers that go from the two center cams out to the sunrise/sunset shutters which you can just see in the bottom left hand corner behind the sun hand. The sun hand rotates once in twenty four hours. This is fed from the main time train. The cascade of gears downwards from the sun hand arbor and the actual one year arbor is driven from the strike train and is stepped once in twenty four hours via yet another 1:5 step down ratio. So that the one year arbor actually only moves once in five days, seventy three times a year. This is why that wheel has seventy three teeth; 73 times 5 equals 365. These two photos show how Buchanan was able to use the extant parts of the clock; specifically the four dial input levers for the equation of time, sun/rise sunset shutters and length of day/length of night dials to accurately locate and shape the cam pack.


The first photo is a section of the only overall profile photo we have of the clock taken before the death of Pouvillon in 1969. This was the only visual source of information we had to go on for the design of the step wheel. It was very fortunate as there was no way we could have guessed at the wheel’s decorative design which is not replicated anywhere else in the movement. The remaining components attached to this wheel’s arbor, the cam pack, we were able to deduce from the components which derive their information from these cams. This information gives us the profiles of the cam’s perimeters, but not any information as to how Pouvillon would have spoked these.  Photo 23 013. This is a view of the new one year wheel fitted to the clock. I’ve tried to take a photograph from as close to the same angle as in the original Pouvillon photograph to compare the proportions of the wheel. And it’s quite interesting how closely we have managed to find this. Photo 23 017. (not shown) Another photograph of the one year wheel fitted to the movement. I’m trying to check out the perspective and see how closely we’ve managed to copy the original missing gear.


Here Buchanan uses a pair of cam calipers to help in taking the measurements needed to determine the cam profiles.

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