Tempcom Instrumentation enlisted to help protect Magna Carta

Tempcon Instrumentation Limited, a leading manufacturer and supplier of temperature sensors, research grade data loggers, process control and monitoring equipment, has been enlisted to help protect Magna Carta, one of the world’s most important historical texts.

Originally issued by England’s King John in June 1215 as an attempt to prevent civil war between the king and his powerful barons, Magna Carta has become a world-famous symbol of justice, fairness, and human rights. Having inspired and encouraged movements for freedom and constitutional government for hundreds of years, the four remaining copies of the document have been awarded ‘Memory of the World’ status by UNESCO.

Mounting a new exhibition to commemorate the 800-year anniversary of the signing of the document on 15 June 1215, Salisbury Cathedral has created a new exhibition to tell the story of the Great Charter – and enlisted Tempcon’s help in finding a solution to ensure the Cathedral’s copy of the text, widely held to be the best surviving copy, remains perfectly preserved while on display.

Preserving the text was of paramount importance. Excessive humidity can cause parchment to buckle as it tries to revert to its natural shape; the parchment expands while the ink remains static, causing ink to lift from the parchment.

Real time monitoring

The display containing Magna Carta has been housed within a tent-like structure to control the document’s exposure to light from the Chapter House’s large stained glass windows. However, as the display cabinet is sealed and protected by alarm systems, a solution was needed that enabled real-time monitoring of temperature and humidity without having to go through a time-consuming and complicated process of switching off the alarms and accessing the case.

As specialists in atmospheric monitoring, Tempcon recommended the supply of the latest Onset HOBO data logging equipment, in particular the brand new HOBO MX1101 Temperature/Relative Humidity data logger. A self-contained device that utilises the latest Bluetooth wireless technology, the MX1101 enables users to access data using Onset’s free HOBOmobile® app for logger setup and data management.

As well as displaying real-time temperature and humidity discretely through the glass cabinet, the MX1101 requires no dedicated equipment beyond a mobile device for configuring the logger or reading out data. This means temperature and humidity data can be accessed in real time by the exhibition team without the need to access the cabinet – making it the ideal choice for use in the restricted access conditions of the Cathedral.

Tempcon also recommended the installation of the Onset HOBO U12-012 to record light levels and understand how they impact the display during different seasons.


“Tempcon were a great help in suggesting the right solution for us to protect such an important and priceless historical item,” said Emily Naish, Archivist, Salisbury Cathedral. “It’s great that I can check the current conditions at a glance, and have the ability to access historical data without interfering with the exhibit.”

“The MX1101 was the ideal device to recommend for this kind of application,” said Jim Copeland, Managing Director, Tempcon. “The device is not only convenient, but in many cases it is an enabling technology as it allows simple access in hard-to-access – or even restricted access – spaces. This is a particular advantage in the museum market where gaining access to cases can be complicated and time consuming.”
FINAL VERSION Magna Carta MX1101
Wireless: Emily Naish, Archivist at Salisbury Cathedral is able to access temperature and humidity data from the HOBO MX1101 logger sealed within the Magna Carta display cabinet.

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