From his web site:
The Celestial Mechanical Calendar shows the day of the week, day of the month and the month. In addition, she indicates the Zodiac Sun Sign and New Moon Ascension sign, has a MoonPhase Ball that indicates a nearly exact reflection of what the actual moon is doing in the night sky. She also has a Full Moon Ascension Window, and an Orrery showing the synodic rotations of the three closest planets, Mercury, Venus and Mars and indicates when they go into retrograde. The Celestial Mechanical Calendar also knows if the month has 28, 30 or 31 days and advances herself automatically.
Check out all the details or -- if your are feeling ambitious -- order the plans to make the Celestial Mechanical Calendar and Orrery.