Dating antiques hinges
A rim lock is mounted on the face or surface of the door.
A rim lock is also referred to as a box lock because the box (or body) of the lock is seen mounted on the door.
There are also companies that sell retrofit hardware that will fit the 2-1/8" hole.
They provide everything but the doorknobs themselves.
The year it was made can also give a good indication of which is which. From 1870 to 1900 bronze was the metal of choice for the manufacture of artistic hardware. Antique hardware catalogs always reflect what kind of metal was used for a specific piece.
Sadly, people frequently search the internet using the keyword "brass" and consequently miss much of the truly fine antique hardware.
A rim lock is the easiest lock to install - bar none!
It is also very forgiving with old houses settling as they frequently do.
For the purposes of dating antique hardware we typically rely on the date of an antique hardware catalogue which shows the item or, in some instances, the age of the building it was removed from. It's usually very hard to tell the difference but, in general, brass will have a yellow color and bronze will have a more rose color.
For the actual installation, first lay the lock body in position with lock at the edge of the door and mark the location of the doorknob spindle and key hole on the door. Drill another two holes for the key and chisel out any remaining wood between the two holes. Screw the rosette and key escutcheon to the other side of the door.
The keeper or catch is typically installed on the flat molding that is flush with the door itself.
Use wood glue to stack the pieces in the hole until they are flush with the door surfaces. With a stained door you will need to be more creative. Rosettes (small round door plates) average 2" in diameter and many rectangular doorplates are as small as 1-1/2".
An edging of gold (or any attractive color) paint can be applied or a thin piece of wood a bit larger than the plate/rosette can be added to hide the plug.
If your door has not been drilled in the past, all the better.