Part of an all bronze marine set. The other knob isN-15702.  Adams & Westlake had a branch in Philadelphia. The plate is marked Royalston and is the same design as the knob and plate shown in the 1901 Sargent catalog with the name Royalston. The attachment is based on US patent number 707375, August 19, 1902 by William Bartholomew assigned to Adams & Westlake. The knob and the rose are held together by an inter bushing that is screwed into the end of the knob stem. The rose is screwed into the lock face. Not pictured is a spindle that side louse inside the knobs and lock. Click picture below for larger image.