Inês Correia, Arquivo Nacional da Torre do Tombo, Lisbon

Recovering the 16th-century Treatise of Seamanship by João de Lisboa: A dialog with cumulative material changes

The Treatise of Seamanship is a paper and parchment codex that includes 20 singular chart maps and a Treatise on the Nautical Needle, dated by the author himself in 1514 (1508, in manuscript).

This codex, called A Brief Treatise on Seamanship is a remarkable masterpiece to the history of the book as well as an irreplaceable and essential testimony to geographical history. It belongs to the Arquivo Nacional da Torre do Tombo and has been an object of conservation treatment since 2009.

As book conservators we all know that codices may have several material changes over time depending on their functional reception. Regarding their structures and coverings, mostly arrive with few original features, caused by restoration, rebinding, resizing or typological variations. We call it historical interventions, and there is no question about its temporal value. Nevertheless, when conservation treatment is needed, material and technical management and stability between structural elements may be difficult to undertake. In order to explore the temporality of this renaissance codex, we used a stratigraphic method, which has shown to be a very accurate tool to manage the material information. In fact, we realised that time (around five hundred years, in this case!) brings us not only changes, but also a history of changes which it is possible to see if we analyse its sedimentation process.

The Treatise of Seamanship has been an object of several rebinding interventions over time, but the late 20th-century one caused serious damages to its structure, mainly due to the vinyl adhesives that were used on the backing. The wood boards and leather covering from the 17th century had been replaced by a cardboard and fabric typology, which represented a significant loss of identity. But fortunately, the covered wooden boards were not discarded and were luckily identified as part of the manuscript. As we will have the opportunity to show, the back wooden board has been prepared (carved in its inner side) to accommodate the instruments of nautical reading - the needles and the compass.

The year of 2009 was the International Year of Astronomy and the National Archive of Torre do Tombo has taken part in the commemoration with a thematic exhibition named “Astronomy in the Torre do Tombo Manuscripts” in which the Treatise of Seamanship was displayed for the first time. The codex was exposed unbound, both text block and the wooden boards on the side, next to a touch screen where visitors could visualise the entire book. Five years later the codex was loaned to another important exhibition, “360º Discovery Science”, this time with a sponsor commitment for its future conservation reconstruction.

The conservation process to recover the Book of Seamanship is finally completed. With stratigraphic interpretation we have optimised the decision-making: more than 640 hours have been put into the project since the first observations, more than 300 hours to gather all the structural elements - to decide which ones to restore, which ones to replace. Between paper and parchment stabilisation, from sewing to covering, all the material elements were registered in order of their meaning to the whole codex as a living object; the history of changing kept by temporal strata (codex fourth dimension) is now available to complement this manuscript characterisation and future comprehension.