This section is from the book "A Treatise On Architecture And Building Construction Vol3: Stair Building, Ornamental Ironwork, Roofing, Sheet-Metal Work, Electric-Light Wiring And Bellwork", by The Colliery Engineer Co.. Also available from Amazon: A Treatise On Architecture And Building Construction.
The plan of a quarter-turn winding stairway, with a quarter cylinder for a continued hand rail, and with regular treads above and below, is shown in Fig. 41. It will be noticed that the treads adjoining the cylinder in both flights are reduced. The benefit derived from the reduction will appear in the curve of the rail and stringer, as it modifies the angle of intersection between the pitch of one straight rail and that over the winders, the stringer, of course, being affected in the same manner.