In 1885 the clock tower, now affectionately known by locals as Big Brum, was added to the Council House. It was part of the first major extension of the building, also designed by Thomason.
Inside, the tower is broken into five floors, accessed by a narrow winding staircase of 159 steps from street level. This first level holds nothing more than two levers for the chime and peel. These allow the ringing to be disabled, for example if recordings are taking place in the adjacent conservatoire.
The massive clock mechanism is housed on the second floor. It was donated by local meteorologist and entrepreneur Abraham Follett Osler, along with the bells. Inside a glazed cabinet, huge golden cogs sit within a blue painted frame, eternally winding and clicking. A pendulum, over four and a half meters long, perpetually swings. From this mechanism wires are carried to the floor above in a central pillar, which then break off into four arms, each one operating an individual clock face.
The roof space is a feat of Victorian engineering, made up of a maze of criss-crossing wooden beams jutting out like reaching hands and casting irregular shadows onto the floor below.
Here amongst the roof beams the enormous bells toll. The largest is the hour bell, giving the tower its title Big Brum, which weighs 3 tons.
At the very pinnacle of the tower, accessed by a small wooden ladder and a trap door, is a small uncharacteristically crude steel and glass shed. This was not part of the original design, but nonetheless forms a major part of the tower’s architectural history and significance. This bird’s nest offers a vantage point from which the whole of the city can be seen and was built during the Second World War to act as look out for fires started by air raids.
Matthew Goer, Associated Architects
The full Hidden Spaces supplements are included in the Boxing Day and January 2 editions of the Birmingham Post