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.