O. MILES NASHUA NH”. Iron construction. This changeable bit key lock was invented by Miles & Eddy and patented in 1861 (US Patent No.33,931). However, it is the only one I’ve seen that is marked with the maker’s name (on the lock bolt and on the key bow). All other ones have “US Lock Co” embossed on the lock. Safe to say this lock predates the US Lock Co version. It is unclear what the connections between Miles & Eddy and US Lock Co were. Presumably they sold the design to US Lock Co.Patent #33931.