|Chart from Valetta, Malta, 2nd April 1872, after undergoing conservation, showing the 'seiching' ©|
A tide gauge installed in the Maltese port of Valetta working in 1871 offers the only continuous record of the sea level in the Southern Mediterranean longer than fifty years. However, some of the paper records it produced have deteriorated.
The project coordinator, BODC's Elizabeth Bradshaw said, "there are a limited number of long-term records of climate data in the world, so rescuing and recovering data is vital for answering questions on climate change and oceanography".
The Department for Business, Innovation and Skills (BIS) have provided £32,000 from their 'Breakthrough Fund' to BODC and the UKHO in order to restore these records and make them available to the public. They hope to digitise the data via a citizen science activity, once this project is complete. Once digitised, scientists will be able to use the data to look for evidence of past tsunamis and climate change.
While modern tide gauges typically only calculate the sea level once every fifteen minutes, this historic analogue gauge made a continuous recording. It worked using a float on the water that, via a system of pulleys and cogs, moved a pen up and down a paper-wrapped drum in a way that reflected the changing sea level.
The British Navy installed the gauge to ensure ships got safely in and out of the harbour and in 1877 Astronomer Royal George Airy wrote about the particularly interesting tidal signal at Valetta, caused by the ocean water sloshing back and forth across the Mediterranean basin (much as it does in a bath). The gauge remained in action until 1926.