On the front of the Octant there is a double peep hole fore sight pinnula, to be used in conjunction with the fore sight horizon mirror. This Octant is also fitted with a back sight peep hole pinnula and back sight mirror. ( the back sight was used to measure angles greater than 90 degrees ) There is also a set of three brass framed coloured glass sun filters that are interchangeable between the index mirror and the horizon mirror.
On the reverse side of the Octant there are two butterfly cam levers for adjusting the mirrors. There is a square ivory plaque inlaid into the frame, this is used to note down sight angles and readings. The Octant also has three brass support legs or feet.
This antique Octant is complete with its original wooden, stepped keystone shaped oak box or case.
Height of Octant: 13.75 inches / 35 cm - Radius of Octant: 11.5 inches / 29.5 cm.
A superb example of this mariner’s navigation instrument and it is in excellent condition considering that it is well over 200 years old.