This is an antique exterior mortise lock by P.F. Corbin Co, circa 1885 in the 'Ceylon" pattern with a brass faceplate, a nightlatch, double keyholes and a thumbturn hub. Strike plate, thumbturn and keys are not included. Backset: 2-5/8", $150. An exterior mortise lock is a lock which is used on an exterior door that has been cut with a pocket or hole into which the lock is to be fitted. Exterior locks are used to both latch and lock the door. Exterior mortise locks commonly include a doorknob hub, through which a doorknob spindle is installed and doorknobs are mounted on each side and secured into place with pins or set screws; a thumbturn hub which accommodates an thumbturn which in turn throws the deadbolt to lock and unlock the door from the inside of the house, and either a keyhole for an old-fashioned skeleton or bit key or a circular hole for a cylinder lock. A cylinder lock is a lock constructed with a cylinder that a locksmith can easily unscrew to facilitate rekeying. The cylinder may contain any of a variety of locking mechanisms, including the pin tumbler lock, the wafer tumbler lock and the disc tumbler lock. Antique cylinders missing the key can be taken to a locksmith to have a new key cut.
Mortise locks have specific dimensions including backset, the measurement from the edge of the faceplate (the strip that shows when the mortise lock is installed in the door) to the center of the doorknob hub; and spacing, the measurement from the center of the doorknob hub to the center of the round part of the keyhole. The dimensions were not standardized in the 19th century so it is important to note the dimensions of your door prior to purchasing a mortise lock.
P. & F. Corbin originated in 1849 when brothers Philip and Frank Corbin, and Edward Doen established the firm of Doen, Corbin & Co., to manufacture ox balls. The company's name changed to P. & F. Corbin in 1851. In the last half of the 19th century they broadened their products to include coffin trimmings, knobs, and stove handles. In 1868 they began specializing in the manufacture of builder's hardware and locks. From this period through 1900 the company produced some of the finest brass and bronze builder’s hardware on the market, in a wide array of finishes and styles in the latest fashions. In 1902 the company merged with Russwin to form The American Hardware Corporation.