At the Swiss Institute for Art Research (SIK|ISEA), Danièle Gros further analysed the globes’ structure using X-ray technology. This method highlighted a number of additional details of the terrestrial globe that rounded out the results obtained using tomodensitometry at the CHUV :
- the metal shaft (axis) crossing the inside of the sphere is encased in a wooden sheath ;
- the shaft is tipped at each end by a wooden calotte ;
- the layers of the sphere are made of (or reinforced with) pieces of cloth ;
- there is an “a”-shaped piece of metal next to the southern calotte, probably serving to fasten it to the layers of paper.
Find out more
- Les globes de Mercator de l’Université de Lausanne. Observations matérielles. Constat d’état. Rapport de conservation-restauration : The Mercator globes of the University of Lausanne. Material observations. Condition report. Report on conservation-restoration, Workshop and laboratory of the Swiss Institute for Art Research SIK|ISEA, Ref. No. 141110 0002: 01/02, October 2015, Margaux Genton, Zurich.
- Inner construction of the spheres : X-rays, computer tomodensitometry (CT) scans and 3D modelling of the resulting images help to better understand how the spheres were made.
- Shells and layers : each sphere is made of two hemispheres comprising multiple thin layers of alternating different materials. Based on binocular magnifier observations, X-rays and CT scans, the layers are made of cellulosic fibres.