le planétaire de François Ducommun
Musée international d'horlogerie,
Rue des Musées 29, 2300 La Chaux-de-Fonds



Planetary clock signed by François Ducommun (1767-1837), La Chaux-de-Fonds, 1816. The mechanism includes the planetary system and a perpetual calendar, both activated by a crank. The central movement represents the solar system as it was understood at the start of the 19th century: the sun is surrounded by seven planets and their satellites. It shows the periods of revolution, rotation and the apsis.

The mechanical section is protected by two hemispheres formed of sheets of paper glued then decorated with the signs of the zodiac and the constellations. These oil-painted designs have been attributed to Charles-Samuel Girardet (1780-1863). The upper hemisphere can be raised to uncover the mechanism. The assembly sits on a wooden support mounted on casters.

  • Overall dimensions: Ø120 cm / height: ~145 cm closed
  • The work has been part of the MIH collection since 1917 and is listed under number V-12.

Aim of the restoration project:

The planet clock is still in working condition, but its mechanism would require complete cleaning. Furthermore, no study of this system has been undertaken to date. It is therefore necessary to conduct an in-depth study which will lead to a publication..

The various layers (base, preparatory layer and pictorial layer) of the exterior of the planet clock, its hemispheres, have undergone numerous alterations, such as cracks, flaking, peeling, blisters and missing sections of the pictorial and preparatory layers. This damage was caused by three main factors (natural movement of the materials, use and subsequent interventions). MIH was already worried about the level of damage suffered by this valuable object in 1994, when it had a study into the conservation and restoration of the globes carried out.

A third point must be raised in conjunction with the restorations of the mechanism and exterior: the conditions for its display.

Currently, the two hemispheres are separated by a plexiglas ring, through which visitors can admire the mechanism. However, this plastic ring rests on a decorated area representing the zodiac and could cause damage to its surface. It is therefore important to resolve this issue, whilst keeping the hemispheres open..

Furthermore, no protection is currently in place around the work. The fragility of the globe and of its painting requires some reflection as to its future presentation.

Intervention on the mechanisms:

  • Disassembly, recording and taking of photographs
  • Cleaning of components               
  • Study of the mechanisms (calculating the gears, diagrams and possible virtual reconstruction, analysis of the positions of the celestial bodies and their proportions)                
  • Report on the work                                                     
  • Possible sub-contracting (e.g.: design of the cam profile)

Approximately 456-656 hours

Other interventions:

  • Fitting the fabric for the celestial background located underneath the mechanism
  • Alteration of the display conditions and security of the work

Intervention by an art restorer:

  • Restoration of the exterior, namely the two hemispheres, and the pictorial band.