Desseins du Pont Projete sur la Tamise a Londre – or Designs of the Projected Bridge on the River Thames in London (British Library Maps C.49.e.76) is a proposal for the construction of Westminster Bridge (opened 1750).
It consists of 1 drawing on multiple paper panels each measuring 490mm in height but joined together the collective width runs to 14740mm – or almost 15 metres. This ‘single sheet’ has been folded into a ‘concertina’ book block, which is attached to boards bound in tan calf at each end. Written and drawn in ink and watercolour, it is part ‘artists impression’ and part mechanical drawing - which collectively make a fascinating record of plans and construction ideas that the architect, possibly the Swiss engineer Charles Labelye (1705-1781?) had for the bridge and embody the origins of a quintessential London landmark and symbol.
However, 280 years on from its creation, mechanical wear and water damage have acted to severely degrade the leather covers and paper substrate. In this condition, there was no practical method of use. Refurbishment began in January 2017.
Conservation at the British Library is carried out under a code of ethics that includes; making repairs that are reversible; conducting them with minimum intervention; and using only archive quality materials. Added to this is the fact that the British Library is a ‘working’ library so options for repair need to be considered for their suitability, functionality and longevity.