Outside the orbit of the planet Mars, the planets Jupiter and Saturn move round the sun in 1 1 years 3 1 5 days and 29 years 164 days respectively (photo 2). The four small balls near Jupiter represent the four greatest moons of this planet: sixteen have been detected so far in modern times. Saturn is here surrounded by a ring and only five moons (23 are known for this moment).

Date Pointer

Outside Saturn's orbit a seventh groove has been cut. In this groove moves a pointer which indicates the date with its outer end and the position in the signs of the zodiac with its inner end. Each sign is divided into thirty degrees.

Parallel lines have been drawn from the date circle to the straight graduation on the cornice. Each division of the graduation is sub-divided into two lots of 23-1/2 degrees and indicates the northern and southern inclination of the sun. As will be seen, photo 3 was taken on the 11th. of April. At that moment, the sun was exactly at the beginning of the 21st degree of Aries, and had a northern inclination of 8 degrees 20 arch-minutes.

The pointer travels round the groove in one year exactly, but according to Eisinga's instiuctions should be put back one day on the 29th of February in a leap year.

Dials for Day and Year

On the southern side of the cei- ling are five more dials (photo 4). The middle one is divided in- to the seven days of the week.