Bluetooth Temperature Datalogger Protects the Magna Carta

Onset HOBO Logger is Reliable and Affordable Solution for Museums


Updating Conservation Efforts to the 21st Century:

Originally issued by England's King John in June of the year 1215 to prevent civil war between the king and his barons, the Magna Carta is 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 have been awarded 'Memory of the World' status by the United Nations Educational, Scientific, and Cultural Organization (UNESCO).

The best-surviving copy of the Magna Carta, currently on exhibition in Britain's Salisbury Cathedral to commemorate the document's 800-year anniversary, is stored in a glass display case--along with an Onset HOBO MX1101 Bluetooth Low Energy (BLE) Temperature/Relative Humidity data logger featuring patented connectivity technology.

"Preserving the text is of paramount importance," said Emily Naish, Archivist at Salisbury Cathedral. "Excessive humidity can cause parchment to buckle as it tries to revert to its natural shape. The parchment can expand while the ink remains static, causing ink to lift from the text. As the room in which the Magna Carta is displayed has large glass windows, it is prone to these kinds of damaging fluctuations in humidity."

Compact Environmental Monitoring:

Complete with large memory, fast sample rates and free software, HOBO loggers are ideal for many different applications including temperature recording and alarming, monitoring building performance and more.

Because the Magna Carta's display case is sealed and protected by security systems, archivists previously had no way to constantly monitor temperature and humidity without going through the time-consuming and complicated process of switching off the alarms and accessing the case. To address this issue, the Cathedral's exhibition team installed the Onset HOBO MX1101 Temperature and Humidity data logger. This compact device measures and transmits data wirelessly to mobile devices via Bluetooth Smart technology.

The MX1101 is a self-contained wireless data logger offering easy installation in a variety of settings such as museums and galleries. Its visual and audible high low alarm thresholds act to keep users on top of developing alarm conditions in the environment.

Monitoring From Mobile:

The wireless data logger also works with Onset's free HOBOmobile™ app for logger setup and data management. This convenient app enables conservators to use their smart phone or tablet to access the environmental data at any time from a distance up to 100 feet, all without having to open the display case! This makes the HOBO MX1101 the perfect choice for use in the Cathedral's restricted-access area.

Using HOBOmobile, curators can also view data in graphs, check the operational status of loggers, configure alarm notifications, and share data files. Users can access data anytime from an iOS mobile device over a 100-foot range. The wireless data logger communicates instantly and enables users to 'cut the cord' by requiring no dedicated equipment beyond an iOS device for configuring the logger or reading out data. This saves considerable time and money in a variety of applications.

"The HOBO MX1101 is an ideal solution for us to protect such an important historical artifact as the Magna Carta," said Naish. "It's great that I can check the current conditions at a glance, and I also have the ability to access historical data without interfering with the exhibit."

For more info on Onset HOBO data loggers, visit our Online Store at or contact a CAS Data Logger Applications Specialist at 800-956-4437.

Contact Information:

CAS DataLoggers, Inc.

8437 Mayfield Rd.

Chesterland, Ohio 44026



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