radius 17.75 inches
This octant has an ebony frame, and flat brass index arm with floral design.
The ivory scale is graduated every 20 minutes from -5o to +95o
and read by vernier with tangent screw to 2 minutes of arc. There is also a back
sight and a back horizon glass that can be used to measure angles greater than
90o. This instrument was probably made in the late eighteenth
century. It belonged to the College of the Holy Cross in Worcester, Ma.