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Disassembly. Remove complications, Lunar indicator, planisphere, tellurian-orrery, sun-moonrise dials, equation of time differential


Pouvillon-9-000.mp3. Photo 9 001. Here we have the planisphere mechanism as well as the drive and the lunar mechanism. Of interest is that Mr. Pouvillon, it appears, to have silvered all components in the lunar and planisphere mechanism. The plates and the gears all appear to be silvered; altogether a dainty piece of engineering. Photo 9 002 is a close up of the planisphere. Of interest to note is the #58 punch mark on the lower left gear projecting from between the plates, also the generally bad corrosion or tarnish of the silvered components but also rust on the blued screw on the upper left. The bevel gear projecting beyond the frame is the input drive to this mechanism.


Photo 9 003 gives us close up of the lunar mechanism. The lower arbor on the right hand side is the in feed. It has a square on the top which apparently is for setting. This gear is only fixed by means of a taper to the arbor (a friction fit). The next gear is an idler and, of course, the third gear carries on to the worm drive to the moon arbor shaft. Altogether a simple and extremely dainty mechanism. The arbor across the upper part of the photograph incorporating a universal joint is the drive that continues up to the orrery. Photo 9 004. Here we have a close up of the lower drive to the lunar dial. Of interest is the construction of the universal continuing up to the orrery. We see what a beautiful, little mechanism this is. The outer diameter of the ring surrounding the universal is only 6.8mm or just over a quarter inch in diameter. The idler gear on the little post with a screw in the top one can see that its line is slightly skewed exhibiting some signs of wear, but otherwise a very nice little unit. This use of a universal joint on the orrery drive to avoid an obstruction is another indication that the orrery was added later. More detail on this will be provided in a later segment.


Photo 9 005. We have a side view of the planisphere. We see a reversing gearbox which gives counter rotating direction between the planisphere disc and the indicator hand. In other words the disc rotates clockwise once in 24 hours or sidereal time, and the hand rotates in the opposite direction at exactly the same speed. Photo 9 006. We have a pin mounted on the dial of the planisphere. There is an identical pin at the 12 o’clock position, 1800 around the dial. As we can see this pin is slightly bent and there appears to have been either a thin wire or thread across the front of this dial acting as an indicator. Photo 9 007. Here we have another view of the vertical drive from the clock to the lunar dial as well as the orrery. As we can see on the right, top we have the bevel gear that is driven by the strike train and it is reduced in speed immediately to the lower arbor which goes to the lunar dial.


Pouvillon-9-007.mp3.  Photo 9 008. Here we have the universal joint removed from the pivot. It is a screw-clamped joint. Photo 9 009. We have a photograph of the orrery which dismounts as a complete unit. The only projection below the square brass base is the in feed arbor that drives the whole unit. Projecting out of the front of the leap year dial in the center towards the base we see another bevel gear which is the drive to the globe. This drive drives the globe at ‘real time’ speed. In other words it moves second by second; not intermittently like the rest of the orrery which is driven from the strike train. Photo 9 010. This is the underneath of the base of the orrery where we can see the gear that accepts the drive from vertical shaft from the lunar train. This drive proceeds upward into the orrery. Also just above the bridge we see an extension or a pin that drives the one year arbor that is missing on this clock. And this arbor carries the cams for the day/night length dials as well as the equation of time cam. To the left of the picture we see the drive from the time train that drives the globe. Also of interest is in the center of the plate we see six screws and the center arbor for the orrery. It appears three screws act as a height adjustment and their heads do not touch the center plate completely. But there are three other counter-sunk screws that pull down a flange against the tips of these three screws giving us a height adjustment for a bevel gear inside the orrery. Click here for a discussion about the tellurian/ orrery assembly.


Photo 9 011. Here we have a clearer photograph of the three clamp screws, flag 5. One appears to be slightly loose and the three jack screws which control the height of a bevel gear on the other side of this base plate. Photo 9 012. We have the lower base plate at the top of the clock onto which the orrery mounts. It’s interesting to note that this base plate has cutouts for the various drives but it also carries the drop-down pillars for the day/night, length of day, length of night assembly. Photo 9 013. We have a view from the left hand side of the clock towards the base of the sunrise/sunset dial. Flag 2 and 6 are pointing to the mounting screws which hold this assembly. It is becoming apparent at this stage that most of the complications mount on exiting portions of the clock. In other words, there are no specially incorporated pads or mounting points for any complication so far that we’ve seen. We begin to see a pattern here of evidence that the complications have been added in an ad hoc manner.


Pouvillon-9-013.mpg. Photo 9 014. We have a rear view of the sunrise/sunset dial. A few points to take account of is that the two sector gears have become disengaged from their length of day and length of night hands or pinions so they are in the incorrect position but they are displayed like this to show the way they have been made. Also of interest is the row of screws around the semicircular brass rim behind the chapter ring which forms a guide for the sunrise/sunset shutters. The input to this gear system is via the bevel gear seen on the right, lower portion attached to the steel bracket which carries this whole unit. Also to note is on the two upper frames carrying the sector gears towards the outer end just slightly past the main chapter ring is an empty hole. It appears to match with a mounting screw hole where the frame attaches to the chapter ring on the front frame. Perhaps Mr. Pouvillon made these frame simultaneously; sandwiched together. Photo 9 015 gives us a close up of the sun hand which rotates once in 24 hours. It’s nice to see the delicacy of the engraving. One does wonder whether there was anything else mounted in the center of this dial (hand). Because we have a flat, machined pad, but this is only a query. We can also see some of the filling has been lost from the engraving in the chapter ring. But otherwise this assembly has largely been gilded and one sees the befit of the gilding in the almost complete lack of corrosion.

Photo 9 016. We have a close up of the sunrise/sunset dial. We can see a very faint marking outline going from the 24 division up through the end of the ‘L’. Also of note is that sidereal is clearly hand engraved while most of the numbers, here we have 24 and 23 appear to be machine engraved. Photo 9 017. We have an arbor missing a hand for the length of night dial. Both on the length of day and length of night dial we have this screw projecting from the side of the frame just above the blued screw which holds the pillar and there is nothing to show what it is used for. One suspects that it might have been a stud for an anti-backlash spring similar to a balance hairspring. But this is only a supposition as there is no collet on the actual arbor or other indication that such a method was used on this dial or the length of day dial. Photo 9 018. We have another view of the sunrise/sunset mechanism with the sector gears engaged with the pinions driving the hands for the length of day and length of night dials.

Pouvillon-9-018.mp3. Photo 9 019. We have the lever and the crank gear from the equation of time mechanism. Here we have gilded components again which show very little sign of corrosion. Starting at the lower end of the lever we have a weight which helps keep the lever in contact with the missing kidney cam. About one-third from the bottom we have a protrusion from the side facing backwards in this photograph, two short pins projecting out from it which seem to be guide pins to keep the lever from falling sideways off the equation of time cam. As this lever is raised and lowered so it partially rotates the gear attached to the blued rod and this gear, in turns, operates on the differential which gives us the difference between mean time and solar time and displays it on the ‘mystery dial’. Photo 9 020 is a bad photograph of the equation of time differential. We also see the vertical arbor just behind the dial that was formerly attached to the glass tube that drove the mystery dial. Also noticeable is that the dial support frame is only attached with one screw and not completely tightened. Whether this was done when the mystery dial was removed for transport or exactly why it is like this is unknown but obviously has to be repaired. Photo 9 021. We have another view of the drive to the glass tube to the mystery dial and also the loose dial support.

Photo 9 022. We have another overall view of the near naked movement with all the complications removed. It is interesting to note that we still have not lost a unity of design due to the complications removed. We’ll see how this idea progresses as we remove the final upper plate that carried the orrery in the next photographs. Photo 9 023. We have a photo of the bare movement showing only the time train, pallets of course, and the strike train giving us the appearance of a fairly basic, standard skeleton clock. Photo 9 024. We have the rear view of the main time dial. It’s nice to notice the curling on the back of the dial. Also interesting are the special countersunk screws which hold this dial to the main frame of the clock. It is a countersunk screw but has also been reduced below the countersunk head to give a very flat screw. So it appears that the screw is countersunk into the front of the dial but it is actually, I should say, counter-bored but is actually a plain countersink. Also interesting is the way Mr. Pouvillon has attached the rim of the dial to the back plate.

Photo 9 025 is a close up of a bezel clamping screw and also shows off the curlage well. Of interest is that we have the junction of the prime support and the main support outer frame. We see the last curling application as a full circle. Photo 9 026. We have side view of the bezel, a close up, showing a worm hole in the brass. Well, of course, we don’t have worms that eat brass so I suppose it is actually a casting defect. Photo 9 027. We have a close up of the equation of time differential and the frame on which the differential mounts or pivots. We see the bevel gear going up to the blue arbor that goes to the glass tube driving the mystery dial. And an interesting feature on the contrate wheel on the differential gear box is very nicely recessed and carries the mating bevel gear that drives the mystery dial, altogether a nice compact, complex little mechanism.

Photo 9 028. We have the equation of time differential mounted in the pivot on its frame. We see a few interesting features, numbered screws as well as identification punches showing their correct location on the contrite wheel. This is a feature that helps any restorer and makes our life a little easier. Photo 9 029. A side view of the equation of time mechanism. Photo 9 030. We have another side view of the equation of time differential and we can see the two small bevels meshing giving us the drive from the differential through to the mystery dial.

Photo 9 031. We have the motion work to the main time dial. We have a copper, or a bronze anti-rattle washer that goes between the minute and the hour gear. The rod coming to the top left hand corner of the photograph is the lever tripping the strike. Also interesting to note is that Mr. Pouvillon has used a hexagonal nut to retain the lower gear in this picture. Photo 9 032. We have a close up the hexagonal retaining nut and washer on the motion work. Photo 9 033. We have a view from the front of the clock with the main time dial removed and we see the major portion of the strike train; the pinwheel that lifts the strike hammer as well as the propeller-shaper governor fan. We also see the slot in the base for both the time and strike weight cords. Another interesting feature seen above the second brass gear from the left hand side of the strike train is the vertical lever coming down from the motion work where Mr. Pouvillon has incorporated an ‘S’ bend to give one a simple length adjustment to get your banking to occur at the correct point.

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