Oddly, the school had a coal-fired central-heating system that belched clouds of black smoke from a tall stack.

A second tall flue gas stack was demolished in a non-explosive way after construction of a smoke cleaning facility, which uses the mentioned tall stack.

These gaps eventually collapse and leave tall stacks at the ends of the headlands.

By offering a slightly taller stack height, these bikes can be ridden more comfortably in an aerodynamic riding position.