The octant was developed prior to the sextant. The reflecting octant was first developed by Isaac Newton in 1699, but did not reach the public until the mid 1700s after further development by Edmond Halley. The reflective octant used a split mirror and was far more accurate than previous instruments since it allowed accurate readings while at sea on a tossing ship. The split mirror could bring the sun (or star) and horizon into the navigator’s view at the same time with practically no optical parallax. It was also the first instrument that could be used during both night a day.
Being one- eighth of a circle, the octant could not measure greater than 90 degrees. Therefore, the octant became almost obsolete once the sextant was developed. There were several navigators who continued to use both the octant and sextant together until the late 1800s
Size measures 33.5mm tall. Polished gold finish.