Eric Watson, Saddleworth, England, 1986

The orrery is hand made of gilt brass with silvered dials, executed by Eric Watson of Saddleworth, England. A clockwork driven model of the solar system depicting the Earth, Moon, Sun and five planets, date on the silvered outer ring, times of sunrise and sunset (Mean Time at 34º03' North and adjustable for change between standard and daylight savings time) and twelve hour chapter ring for the time, also adjustable for the seasonal time change. The precession of the zodiac on a separate chapter ring that rotates once every 25,800 years. Designed to show no visible error for at least 100 years

Epicyclic designed gearing drive the planetary motion, each with about 600 teeth, and over 90 wheels in the gear train. The Earth is formed of hammered and enameled copper, the continents overlaid in silver. It has the correct tilt and gearing to accurately depict the seasons and the Moon's bright side stays facing the Sun.

The 8 day clockwork mechanism is chain fusee driven. A specially engineered and jeweled large club tooth lever escapement, beating seconds and incorporating a remontoire, provide adequate impulse to drive the massive number of train gears. Balance wheel is bi-metallic, all pivots in the escapement are in jeweled chatons. The remaining clockwork run in ball races. Lantern pinions are used in the clockwork section.

A drawer at the base houses the custom winding and setting keys.

Watson made five orreries in the 1980's, all of similar design but each with individual design features with this one the most complex; having a dial to depict the precession of the zodiac and seasonal time adjustments. Watson's orreries were some of the finest free-standing orreries created in the last 100 years.

Watson's main focus was on the creation of not just an orrery but a beautiful machine. Something that would stand out from all prior orrery designs. To accomplish this he dispensed with the normal practice of having a set of arms for each planet driven from a central stalk. Instead he employed the concept of epicyclical gearing by first designing a rotating armature driven by the clockwork that contained most of the over eighty wheels in orrery section of the machine and used a set of three fixed gears located concentrically to the stalk to drive the wheelworks within the armature as they rotated around the center stalk. In addition he used three eye-catching concentric toothed rings to drive the outer planets of Mars, Jupiter and Saturn. Each ring having over 600 teeth and measuring between 11" to 12" in diameter. The armature rotates counterclockwise every 365 days; carrying the Earth/Moon system but must also provide a drive to the outer plants which move far slower. To do this there are three drive wheels driven by a fixed gear ring mounted to the top circular plate of the clockwork, but is concentric with the center stalk which is also mounted to that same plate. Those wheels in turn mesh with the rings and rotate clockwise with the right speed to counteract the one year rotational speed of the armature. So as the armature is dragging the rings counterclockwise once per year, the three drive wheels counter this to push the rings in the opposite direction to net out the correct orbits of Mars at 1.88 years, Jupiter 11.9 years and Saturn 29.5 years.

The inner planets and the sunrise/sunset dial work are driven from a second fixed gear on the stalk a third fixed gear just below drives the annual calendar chapter ring and from which a second chapter ring is driven to show the precession of the zodiac at 25,800 years per revolution. This last feature is not found on any other of his orreries. The clock time indication is independently driven directly from the clockwork mechanism.

Watson is the only maker known to have employed epicyclical gearing to create a unique orrery design.

Dimensions overall with planets: 16" wide, 11 5" high. Without planets: 12" diameter, clockwork movement plates, 5" diameter.

Click on pictures for more details 

Photos below of the completed orrery were made with it removed from the stand. The white background reveals more detail.

This video shows an overview of the functionality of the orrery.

This video shows some technical details of the machine.