After looking at all of the doors, it was possible to determine that there were two general types of locks installed in the Mansion during the Madison era.  The earlier type, which was installed on the doors that dated to ca. 1764 and ca. 1797, were called rim or box locks.  These locks were often housed in iron or brass boxes and were screwed directly onto one of the door’s faces.  The second type of lock found at Montpelier are called mortise locks.  Unlike the rim locks, these locks were designed to be installed in mortises cut into the door and so most of the lock was hidden from view.  Mortise locks were developed at the end of the 18th century and so at Montpelier they dated exclusively from the ca. 1812 construction period.