This pair of standing 21-inch English globes was made by John and William Cary – well-known map-publishers and globe-makers of the late 18th and early 19th centuries. Representing the largest size of globes produced during the 1800s, the pair consists of a terrestrial globe and a celestial globe. The terrestrial globe shows the tracks and discoveries made by Captain James Cook as well as that of Captain George Vancouver. The celestial globe features star coordinates and constellations.
This is the only pair of globes in the NC, kept as part of the collection of maps and charts.
The conservation of the globes was a collaborative effort between an objects conservator and a paper conservator – in preparation for the globes’ display in An Old New World at the National Museum of Singapore.
Pair of terrestrial (right) and celestial (left) globes
Examination of the structure and surface features of the globes
Conservators engaged in a range of examination processes to understand and to study the condition, material, damage, and construction found on the globes.
It was important to build up knowledge about the globes in order to devise a conservation treatment plan for the care of the globes.
When the surface features of the globes were examined using a digital microscope, the following details were observed:
The original print ‘U’ and in-painting of “L” (left); Repair with new paper and in-painting of lines (right)
Marks created from burnishing the paper surface (left); Paper in-fill (right)
Plaster layer can be seen through the holes on paper support (left); Metal particle from the paper making process (right)
UV-induced visible fluorescence examination
The UV examination revealed the different varnishes on the globe and its stand and led to the discovery of many old repaired areas.
The varnish on the globes and stand fluoresce differently under UV light (left); The repairs (in blue) on the paper support – made of a different paper material – were only visible under UV light (right)
The repairs (in brown) located along the adhesive join line that connects both hemispheres
Conservators and curators worked closely to discuss the treatment needs of the globes.
Curators were concerned about the legibility of the globes’ inscriptions, which are obscured by the glossy and discoloured varnish. However, it was risky for conservators to remove the varnish due to its complexity – possibly involving multiple layers of original and new or added varnish.
After discussion with the curators, a decision was made to leave the varnish intact and untreated.
X-ray imaging unveiled the globes’ interior – revealing essential information about construction methods, points of weaknesses, as well as old repairs.
As X-ray is non-invasive, this method allowed conservators to examine the globes’ interior without disrupting their surface or structure.
X-ray image of celestial globe shown from top-down view (Left)
By allowing us to separate and select individual layers and parts of the globe shell, the CT scan provided a defined form of the hollow interior. We were able to confirm the thinness of the shell, as well as the presence of a metal weight – used as a counterbalance – within both globes.
CT scan image of celestial globe
Construction of the globes
From this investigation, we found that each globe is comprised of two wooden hemispheres joined at the equator to form a hollow sphere with a metal weight within it to act as a counterbalance for the globe. Internally, the sphere is supported by a wooden centre pillar which holds the hour ring, pivot clamp, nails, and meridian ring in place. The meridian ring has grooves, enabling the globes to be rotated on two axes.
Covering the wooden spheres is a plaster layer that is overlaid with printed paper. During the globes’ construction, the paper support was burnished, sized, hand-coloured with water colours, and, finally, coated with varnish.