Octant

One octant. The octant has an ebony wood body with brass mechanical parts. It has a peep sight and an adjustable horizon mirror. The graduated arc on the bottom of the sextant is marked from 0 to 105 degrees and includes an adjustable 0 to 20 vernier scale which allows the angle to be read to the nearest minute. The graduated arc scale and vernier scale are both made of ivory. The sextant includes three glass index filters (one green and two red) at the top of the frame and two glass horizon filters (one green and one red) near the middle. All of the filters can be rotated in or out of the line of sight depending upon the sunlight intensity when sights were being taken. The frame arc is marked: "Spencer, Browning & Co., London," and "Made for D. McGregor, Greenock & Glasgow." Script letters, "SBR [Spencer, Browning, Rust]," are shown at the center of the graduated arc.