Horologium II

I have a man to meet in the British Library, so I walk up the street towards Euston, to one side of which is the British Library. I can remember when trying to walk these streets was slow and difficult; crowds of people in both directions, all of them paying no attention to anyone else. Collisions were frequent and angry, stupid people saying stupid things. But that was before the Horologium arrived. Now there are sparse groups of people and the occasional individual, all watching where they're going and what they're thinking. No collisions at all. And some small part of me, despised by the rest of me for being a traitor, is glad.
The British Library is a closed-stack library, which means that first you must apply for membership, and assuming this is granted, you must then use their catalogue to find the book or books you have a particular interest in and then request the books. Often they will be brought to you. Occasionally, you will be brought to them. More rarely still you will be refused the book you have asked for. If you are well-behaved and in good standing with the library, there may be a reason for the refusal, such as the book being sufficiently rare or delicate that it simply isn't available for reading. Then you can apply to the Library Lords (like Law Lords only significantly more secretive and powerful), providing signed affidavits of the validity, necessity and urgency of your research, personal recommendations from important people, and perhaps extending access to rare volumes of your own (should you possess such), and perhaps as a result you will be shown to a Reading Room where the book will be exhibited and burly Librarians armed with tasers will keep you at an appropriate distance.
Now and then there will be no reason given, and further questioning will cause your membership to be revoked. The library will not lie and tell you that the book is not available, but it will be made clear that the book is not available to you.
And then there are the books that only very senior people in the library know exist, that do not appear in the catalogues and are kept in rooms that do not appear on the blueprints of the building. As the door at the back of the British Library opens, I enter, and proceed along a corridor to take me to just such a room.
My contact, a small man in a grey overcoat, says nothing as he leads me along. We pass a room whose significance I have deduced: it is room 5-sub-2. Mathematically, a subscript 2 can be used to indicate a base, and here it means that 5 should be written in binary: 101. Room 101 is used as a trap; if you open the door and venture in you will fall into a sink-hole and drown. There are other labelled doors that we walk past whose purpose I have not yet deduced. We are going to an unlabelled door, a Reading Room.
The one where the blueprints for the Horologium are kept.