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Before more detailed drawings could be made and a formalization of the entire design could be set, certain subsystems had to be tested. These were limited to those that had never been tried before. Other systems, while more complex, like the orrery and perpetual calendar were not tested as these had been done before and their designs well known. Below is a working model of the main wheel (one of four in our movement). The maintaining power used is epicyclical - sun and planet. However, instead of the planet wheels remaining on the same plane as the center sun wheel, they are turned 90 degrees for greater visual effect. In the actual movement the planet wheels will also be spoked; not left solid. The idea that needed testing was the compound barrel system. This is the reason the barrel has two different diameters. The drop for the clock was critical as we have a large amount of moving parts - mobiles - to power with only a 4 foot drop. While the weights will be compounded once in the normal manner, this addition will further enhance the effect without a further pulley requiring another 100% increase in weight. Original drawing showing this is here.
While the design of a planisphere is well known, this one has an additional complication. I had seen my inspiration for this in the February issue of the Horological Journal, last photo. In addition to the star plate showing the movement of the stars at a specific latitude, there is a moving sun-indicator that shows how it moves through the zodiac throughout the year. This had not been seen by me or the fabricator elsewhere, so we had to devise a mockup to test this.
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