The construction of a remarkable helical staircase was made for a whole sale milliner's showroom in London, England. It was the purpose of the architects to provide not only a pleasing central link between two showroom floors but also to create a dramatic approach for mannequins as they turn in their descent from the changing rooms to the showroom floor. The staircase spans the full vertical distance of 13 feet from floor to floor without any intermediate support. The flight is 4 feet 8 inches wide and it turns through an angle of 294 degrees. It was designed as a helical beam and the minimum thickness of the concrete is 7 inches. Longitudinal bars and transverse links were used to resist torsion and a reinforced concrete hinge was provided at the bottom of the flight to prevent bending forces from being transmitted at the floor slab. The upper end of the staircase, however, was made continuous with the floor slab at that level.