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.
In Fig. 40 is shown a plan of a quarter-platform stairway with a quarter cylinder for a continued hand rail. Any radius of cylinder considered desirable may be used, but if the risers o b and o' b' be put at a distance equal to one-half the width of a tread from the point a, the intersection of the center lines of the rail, the wreath piece will conform to the common pitch of the flights. If the front stringer is a close one, and the risers are placed as shown, the effect will be more agreeable than it would be if the risers were placed either nearer to, or farther from, the point a. This arrangement of the risers will allow of a graceful curve in the development of the front stringer and the hand rail, while if placed in any other position, the result would be an unsightly crippled rail and stringer.