No flames in the library
From Dreaming Spies:
The Library’s policy [was] enshrined in the oath’s second declaration: item neque ignem nec flammam in bibliothecam inlaturum vel in ea accensurum; “not to bring into the Library, or kindle therein, any fire or flame.” ….I had to agree, that when it came to Duke Humfrey’s library, a tinder- dry piece of architecture filled with priceless and irreplaceable paper, I would probably opt for the conservative view, even though the lack of lighting made for short hours, particularly during the winter. At least by my time, there were radiators—early generations of scholars had been a hardy lot, shivering at their desks until the library had figured a way of heating the place that did not involve the kindling or bringing-in of flame.
Duke Humfrey’s was built to house a collection donated to the University in the mid-fifteenth century. And yes, one can sit here and read. Oxford is an extraordinary city.