One of the oldest sets of records held by the National Archives of Australia contains information that can help us understand one of the modern age’s most pressing problems – global warming. These records have recently undergone a full conservation treatment to ensure they survive into the future.
The records, stored at the Archives’ Hobart Office, date back to 1837 and comprise meteorological observations made at Port Arthur by Thomas Lempriere (1796–1852), who was Deputy Assistant Commissary General at the penal colony.
We know much about Lempriere as he was an ardent diarist. His diaries are held in the Mitchell and Dixon Collection at the State Library of New South Wales. Lempriere was an erudite man. He was an accomplished artist and spoke five languages. He was naturally curious and spent much time examining the fauna of the region, going to the extent of learning how to preserve animal specimens from a taxidermist in Hobart Town. These specimens and other curiosities were displayed in a small museum established by Lempriere.
Another of Lempriere’s great interests was meteorology, and it is his meteorological records that are held by the Archives. These records are in the form of handwritten tables listing temperature, rainfall, humidity, barometric pressure, spontaneous evaporation, prevailing winds and cloud formation. They tell us that, for instance, on 29 September 1858 there was a ‘heavy fall of hail and rain during the day, squally in the morning’.
Lempriere’s global benchmark
The records also include tidal information, which is of most interest to modern science. To facilitate the data gathering, in 1841 explorer James Clark Ross and Lempriere carved a sea-level benchmark line in a sandstone rock on the Isle of the Dead, near Port Arthur. This is one of the oldest such marks in the southern hemisphere and is still extant. Data for 1841 and 1842 – the time the benchmark was carved – is held by the Royal Society in London. The rest of Lempriere’s records are held by the Archives.
Scientists from the Commonwealth Scientific Industrial Research Organisation (CSIRO) Division of Oceanography and the Southampton Oceanography Centre in the United Kingdom have recognised the significance of Lempriere’s records. Dating back nearly 170 years, they are a very rare example of long-term sea-level records. They provide a valuable opportunity to ascertain changes in the sea-level over the longer term, and to contribute to a greater understanding of global sea-level rise.
In 1999 the University of Canberra, the University of Tasmania and the CSIRO established a sea-level monitoring station at Port Arthur. Evaluating the data gained at this monitoring station against Lempriere’s original tidal records has enabled the first comprehensive comparison of 1841 and present-day Port Arthur sea-levels. The results of this study show a rise in the sea-level of at least 13 centimetres since 1841.
Conserving Lempriere’s work for the future
Given the significance of Lempriere’s meteorological records, the Archives carried out a full conservation treatment on them to ensure their survival.
From a conservation perspective, the records were of concern for two main reasons: the paper was brittle and had many tears and losses; and Lempriere had written in potentially unstable ‘iron gall ink’. In extreme cases, iron gall ink can become chemically aggressive and eat through paper, leading to a condition known as ‘lacing’.
All conservation treatment carried out on the records was done using minimal moisture, which can activate iron gall ink. Most of the sheets of paper were folded, and their brittleness meant that the folds had to be ‘relaxed’ with moisture before they could be flattened out. Instead of simply applying water to the creases, the sheets were placed in a humid chamber, which gently softened the creases.
A lining was adhered to a small number of badly damaged sheets to ensure they were not damaged through handling. The standard lining process involves completely wetting the item. As this was not possible, the remoistenable-lining method was used. This involved applying a sheet of strong Japanese tissue coated with a layer of starch paste to the back of the record (in much the same way a stamp is applied to an envelope). Before backing, each sheet was carefully cleaned using preservation-quality erasers.
After treatment, each sheet was placed in an archival-quality sleeve and returned to storage. The Archives is now confident that the records are in a good enough state to survive into the future.
1 Pugh, Coleman and Hunter, ‘Measuring sea-level rise at Port Arthur’, State of the Environment in Tasmania, Hobart, 2002, soer.justice.tas.gov.au/2003/casestudy/4/index.php.
by Ian Batterham, conservator at the National Archives of Australia