Circular date handstamp
This small post office circular handstamp has a solid wood die and set screw to fix changeable type for the date. The markings are illegible, but they may be "N.H." for New Hampshire. The center mortise only accommodates month and date type, but there is no type for the year. This places the device in use during the 1860s-1870s. At that time, the year was not perceived to be important because the receiver knew what year the mail piece was sent.