Clock No. 1

The first clock made by Rasmus Sørnes is a mantelpiece clock. Based on the years engraved on the front dial, he appears to have been working on this clock between 1937 and 1947, although reference [1] claims it was completed in about a year.

Features

Standard time
Greenwich Mean Time
Sidereal time
Moon phase
High and low tide
Sunrise and sunset time
Julian number
Earth globe showing day and night
2-D firmament
Orrery with six planets
28 year solar cycle
19 year lunar (Metonic) cycle
Julian Calendar
Solar and lunar eclipse indication

The firmament is visualized on a two-dimensional dial, holes are drilled for the larger stars and the dial is illuminated from behind to make the stars visible in the evening. A switch allows the clock to be run forward and backwards in time.

Escapement

The clock is controlled by Sørnes' own invention, an electromagnetical balance wheel escapement. It feeds the system with a constant revolution of one rotation per second and is in this clock powered by two 1.5 V batteries. He experimented with the escapement for many years but eventually resorted to more traditional solutions.

Clock No. 2 and 3 uses the same escapement, but clock No. 3 has an additional synchronous motor and a pendulum driven escapement installed, and in clock No. 4 only the synchronous motor and pendulum driven escapement remains.

Miscellaneous

It has been told [1] that when finished, he was not satisfied with the result. The accuracy of the celestial orbits suffered as the calculations were based on regular calendars without full correction of the irregularities. Nevertheless, he must have learned alot from this construction, and he kept improving the design in the coming clocks.

Location

The clock is in private possession by the Sørnes family, and is temporarily on display at Inspiria Science Center, Sarpsborg.

Source reference

Tor Sørnes: The clockmaker Rasmus Sørnes, Sarpsborg 2008
Erik Ødegaard: Sørnes astronomiske ur nr. 1
All images in this article are copyright Erik Ødegaard.