Brass sector, slightly larger than usual, plain metal plate (with small hole in it) at the end of the arm which fits into the other arm when it is closed.
Date
ca. 1600
Manufacturer
Elias Allen
Place Manufactured
England
Dimensions
2 x 9 x 1/4 in.
Category
Pre-computer/sector
Subject
Proportional compass; Hand calculation; Military applications; Analog