After looking at other stairs and consulting with architectural historians, it was determined that the lone surviving newel post fragment indicated that Montpelier's ca. 1797 stair used a refined early-Federal style trim that would have been common in late 18th century Virginia.  The key factors in making the determination were the square shape of the newel and its small size.  After finding stairs that shared both of these factors, such as the stair at the ca. 1790 Ellwood in Orange County, VA, it was possible to extrapolate a design for the stair based on these surviving examples.  Specifically, the Restoration Team found that almost all of the stairs that featured these newels had thin, rectangular balusters and a molded, bread-loaf shaped rail.