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Continue disassembly and restoration of the mystery dial. 

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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.

Pouvillon-25-001.MP3. Photo 25 001. Here we have the upper bevel attached to the glass tube which drives the equation of time mystery dial. We can see the adhesive; haven’t been able to identify it and also the pressed-on, cannibalized bevel gear on the brass bush at the tip and, of course, the pivot at the end. This glass tube at the other end is unfortunately broken and will have to be replaced. In this section the term mystery dial and equation of time dial are used interchangeably to refer to the same dial. The dial is in the style of what are commonly called mystery clocks where there is no apparent connection to the hands. These typically are driven by a clear glass disc attached to the minute hand which is in turn attached to a small 12:1 gear box in the center of the dial to drive the hour hand and hidden behind the minute hand as has been described earlier.

The reference to equation of time is actually a misnomer. The dial indicates ‘sun time’ that is it tracks the time the sun moves through the sky. Therefore on any given day throughout the year when this dial indicates 12:00 noon the sun will be directly overhead. Of course the sun is almost never exactly at dead zenith in the sky when our domestic clocks indicate 12:00 noon. In fact this only occurs four times per year. The difference can vary by as much as 16 minutes 33 seconds where the sun is ahead to 14 minutes 6 seconds when it is behind. This is caused by the obliquity of the ecliptic (the plane of the Earth's annual orbital motion around the Sun), which is inclined by about 23.44 degrees relative to the plane of the Earth's equator; and the eccentricity of the Earth's orbit around the Sun, which is about 0.017. The equation of time is actually the difference between ‘sun time’ as indicated on this dial and the time on our clocks. If this mystery dial’s minute hand were to be superimposed upon the main clock dial, the difference between the two minute hands would be the equation of time. I find it interesting that Pouvillon decided to use this type of dial for sun time. The sun’s time has no connection, and neither do the hands on the sun time dial. Photo 25 003. We have the lower pinion which will be attached to the lower end of the glass tube. In this picture it is actually inverted. Again we see what I believe is a borrowed steel pinion pressed onto a brass collet. We have evidence of rust, but very little evidence of wear in this picture. Photo 25 006. We have the rear face of the mystery dial, the equation of time dial. In the center of the uppermost glass disc we have a chaton which is a bearing. It appears to be a pivot projecting through the chaton, but in actual fact it’s the minute hand arbor. Right up against the shoulder if you look carefully you will see this little cross hole drilled through it that should have a taper pin to retain it. Around the outer rim of the glass we can just see the teeth of the drive disc.

Photo 25 007. We have a view from the top of the equation of time dial. We have in the foreground a screw holding the bezel, the engraved, gilded bezel which obviously is rusting a little. Also just next to the twenty second marker we have the tip of the minute hand. It appears that this hand was not blued I still have to investigate this but there’s no apparent signs of bluing on this hand, but this will have to be reviewed further. Interesting to note is that the numerals are actually painted or printed onto the outer surface of the glass disc, in other words they are fully exposed, probably because this was easier for Pouvillon to paint, rather than trying his hand at reversed painting. Photo 25 008. We have the little cover plate, Temps Vrai. This translates as Real Time. I think this is a nod to Pouvillon’s idea of a more rural and natural existence as he probably experienced in his small town of Nogent-sur-Oise. The surface of this loose plate appears to be silvered although in my opinion at present I think it was actually plated or possibly what is known as French silvering. It is not standard silvering. The upper screw next to the ‘V’ obviously has a damaged slot and we also see a little of the wax filling is missing on the ‘Mysterious’ ‘r’ and ’s’. Also identifiable just below the ‘e’ we can see a screw through a flange and three identifying center punches. Photo 25 009. We have the main dial. We can see corrosion on the polished steel hands also the bad condition of the dial, particularly for instance the twenty and also the ‘V’ for the five hour.

Photo 25 010 is a photo of the motion work or the 12:1 reduction mounted in the center of the dial between the glass discs. Also of interest to notice is on the right hand side inside this disc we have a semi-circular cutout in the rim which performs no apparent function. Photo 25 012. The other two motion work wheels; the center arbor and also the hour hand gear. To the top left hand corner we can see the cutout in the rim of this glass disc which is as you can see right at the 12 o’clock position. For no reason is it required. I am wondering whether we here again we do not have a borrowed component. Pouvillon-25-014.MP3. Photo 25 015. We have a rear view of the dial disc again we can see the cutout just at the ‘Buchanan’ on the scale ruler. We also see the actual size of this dial being, the glass disc being approximately 32mm or just over 1 inches in diameter. The material for the ring around the disc is not brass, it appears to be nickel or some non-standard material; it doesn’t appear to be silvered.

Photo 25 017. We have the center arbor and also the two gears forming the 12:1 ratio for the motion work. Photo 26 001. We have a photograph through a microscope of the back end of the minute hand arbor showing the cross hole with a fairly substantial counter sink in the side. The next photo will show the opposite side of this same arbor. All of the following microscope photos are at a 44x magnification. Photo 26 002 shows the opposite side of the minute hand arbor just to the left of the hollow we can see what appears to be another attempt to start drilling another hole. There’s a fairly substantial conical blemish in the arbor, also of note is the rough finish on this arbor. It is my opinion that this arbor was made by Mr. Pouvillon; we have a few more reasons to support this shortly.

Photo 26 003. Just a photograph to show the small size of the hole through the center minute hand arbor. The diameter of this hole is approximately 0.18mm or 7 thousands of an inch in diameter. Photo 26 004. A microscope photograph of the ten-toothed pinion on this arbor. Again note the rough finish on this component. When I say rough, this is a comparative statement. In real life it is rather nicely finished it is just greatly magnified. Photo 26 006. We have an end on view of the ten toothed minute hand pinion what I’d like to comment on in this picture is the apparently bad form on this pinion and when compared to a commercial pocket watch or watch component it appears very crude. But if Mr. Pouvillon made this himself, I’d be rather impressed by the amount of skill that would be required to make such a component.  

Photo 26 012. The 32 toothed output gear that holds the hour hand, again a microscope photograph primarily for ease of obtaining a tooth count. Please note that this gear is just under 3mm in diameter or somewhat less than 1/8 of an inch. Also note again a rather odd tooth shape; whether this was a handmade special, I wouldn’t be too surprised. Pouvillon-26-013.MP3. Photo 26 014. A microscope photograph of the ‘35’ numeral showing damage to the dial (the numeral),  Photo 26 015. The same numeral after it has been repainted.


Photo 26 017. Again the numeral ‘20’ showing the loss of paint. Photo 26 022. The repainted ‘20’ numeral.


Photo 26 019. Again we have numeral ‘8’ and damage to it. Photo 26 021. The number ‘8’ Roman numeral after restoration.


Photo 26 018. Here we have the partially restored dial most of the Roman numerals from ten through to seven have been repaired as well as all the minute numerals. The dial still needs to be finely cleaned as well as the center decorations needing to be restored. Photo 26 020. We have the mostly restored dial. We still need to finely clean the glass disc and remove, obviously, the blot next to the ‘45’ numeral. The glass was not first thoroughly cleaned to avoid losing any of the fine detail needed to reproduce the painted figures that could have been lost through cleaning.

Photo 27 001. This is the brass ring gear around the center glass disk of the equation of time dial or mystery dial. The purpose of this microscope photograph is to show the buildup of excess adhesive on the teeth of this gear which we have since removed in the cleaning process. Photo 27 002 is a side view of the brass ring gear attached to the glass disc of the mystery dial. Photo 27 003 is the opposite side of the glass disc showing the recess in the brass ring gear that holds the glass, in other words we have a flange behind the glass and it is filled in with a black adhesive this photograph is approximately 44x full size.

Photo 27 004. An overall view if the mystery dial and the glass tube on the left which is to replace the broken fragment you can see alongside of it. The new tube is a smaller diameter than the original tube that the dial is attached to and fits inside that tube. Photo 27 005. Here we are machining away an attached sleeve on one of the adaptors that fit into the end of the glass tube for the drive on the mystery clock dial, one of what has earlier been referred to as a spigot. It is clear, the glass tube has obviously broken previously because we have the same sleeve, or bush on each end of the adaptors. It's curious that this tube was broken before or ever broken at all, given the outside tube is intact. One would think that if there was an external trauma to this area it would be the external tube to be broken first. It's unlikely that there could have been any internal forces in the drive between the clock and the mystery dial motion works that could have been great enough to break the tube. The small, delicate 12:1 gear box at the center of the dial would have stripped first. Photo 27 008, another view of the sleeve about to detach itself. I’ve machined it down to foil thickness and it has broken the adhesive bond and it is busy sliding off.

Photo 27 009 is the adaptor bush with its steel insert pivot and the bevel gear drive to the mystery dial. Photo 27 010. A bad photograph of the small bevel gear about to be riveted back onto the brass collet.

Pouvillon-27-011.MP3. Photo 27 012. The punch I have selected to rivet or expand the center spigot of the collet into the bevel gear drive. This procedure was necessary because the bevel had become loose upon the spigot. Photo 27 013. We have the collet placed on the anvil of the staking tool and the bevel gear placed on it ready for riveting. Photo 27 014. We have the punch inserted into the guide of the staking tool and positioned over the bevel gear . Photo 27 015, (not shown). You can see if you look carefully the circular ring in the edge of the center spigot of the brass collet which has expanded the brass outward and firmly gripped the steel bevel gear. Photo 27 016. A slightly better photo showing the riveted collet.

Photo 27 017, shows the new glass arbor or drive shaft with the two attached collets. Below is the original broken tube. We’ve used here the traditional shellac to fix the two spigots into the glass tube for two reasons. It is, firstly, a proven adhesive, also very simple to remove or adjust. As opposed to modern adhesives which may have a greater holding power and unknown life span and generally difficult to release if you want to adjust or reposition anything. Photo 27 018. The temporarily reassembled mystery dial, with the restored dial and the engraving refilled and the new drive shaft. Photo 27 019, (not shown). Another view of the completely reassembled mystery dial. Photo 27 020. Yet another photograph of the assembled mystery dial.

Pouvillon-27-020a.MP3. Photo 27 021, (not shown). This shows a test rig to establish whether or not the movement is rocking and causing the clock to stop due to lost energy. We have a dial gauge firmly mounted to a steel bar clamped to the work bench and reading against the suspension support (of the clock). Photo 27 022. Another picture of the dial gauge measuring the amount of rocking. We are actually recording about 0.8 of a millimeter rock to the top of the clock. See also video below. This could be a problem as the frame is relatively delicate in comparison to the heavy pendulum. However as the pendulum is supported by the more robust rear column uprights we should be able to correct the problem. Pouvillon-29-000.MP3. Photo 29 001. We have one of the differential contrate wheels that is part of the equation of time mechanism. Of interest in the photograph are the four countersunk head screws in the cranked (angled) spokes, and this wheel is in apparently two-part construction with the center spider or four spokes which end up near the rim of the wheel and the actual geared contrate wheel or bevel gear and the four little tabs projecting from the lower section of the rim up until the first step of the cranked spoke. It’s of interest to notice that this is not a plain contrate wheel but actually beveled and I would say clearly constructed by Mr. Pouvillon. It bears most of his hallmarks which are non-standard styles or unique forms of construction. Also the screws are not highly finished which is more or less consistent through the later construction phases. Just below the center of the spokes you can see a bevel gear attached to the collet which actually drives the bevel to the glass tube to the equation of time or mystery dial. Photo 29 002. We have the rear view of the same bevel, contrate wheel for the equation of time dial and you can see the small bevel that drives the vertical glass arbor to the mystery dial. This steel bevel, I believe, is a standard pocket watch winding bevel and one of the components Mr. Pouvillon has borrowed from elsewhere.

Photo 29 005. The cranked contrate wheel or bevel gear and the matching bevel that forms part of the differential unit. This bevel is cut by Mr. Pouvillon as you can see it is of conventional bevel construction not the double bevel as we see in many of the borrowed steel bevels and also the collet appears to be part of the gear. Photo 29 006. Yet another view of the differential bevel. Photo 29 007. We have the clock running with the mystery dial fitted in preparation for the manufacture of the missing equation cam. The white tube on the upper left hand side is a strut preventing the movement from rocking while test running. The movement, in fact, is not bolted to its base and standing loose and rocks quite considerably and, of course, the clock stops.


Photo 29 008. Here we have the equation of time differential. It is the slightly lighter shaded section or gear assembly. At the bottom of the picture we have the second hand arbor, that’s the black line projecting diagonally upwards to the right and that gear revolves once an hour which meshes with the plain wheel just above it which it backs up against the differential bevel gears and this wheel rotates once an hour. It’s attached to the differential bevel that is virtually touching it and rotates this bevel once an hour. The center arbor of this assembly is common with the pinion up against the steel frame. And this bevel is rocked by the next wheel up with the crank arm and the vertical rod going up to the equation of time cam. This arbor when rocked rotates the center arbor of the differential and rotates the differential gear which then displaces the contrate bevel up against the ‘Y’ frame, the thin bronze ‘Y’ frame and accelerates or decelerates the equation of time hand to provide you a rotating hand that leads or lags mean time. Photo 29 009. Here we have the equation of time differential and compared to the previous photograph we will notice the rocking lever is in the ‘down’ position virtually at 9 o’clock it’s rotated the small pinion on the differential arbor in the clockwise direction and lifted the differential pinion to the 11 o’clock position. And one can then follow the equation of time hand has accelerated somewhat in comparison with the mean time dial, on the main dial.





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