Description:
This is a standard English backstaff. This one, however, is missing the sighting vanes that were essential in making the altitude measurements. The small semi-circle scale is graduated from 0-65°, divided in degrees, while the large graduated limb has two distinct scales: 65°-90° and 0-25°, the latter divided every 5'. Diagonals are used for precision readings, an early form of vernier. The space where the owner of this backstaff would have engraved his (rarely her) name has been left blank.