The Sextant was invented by Admiral John Campbell in 1757 after he discovered that the Octant was unable to measure angles large enough for Lunar distances ( Distance between Moon, Sun or Stars ) so he increased the 90 degree angle of the Octant to 120 degrees which formed the Sextant. He then engaged the nautical instrument maker John Bird to construct the first Sextant in 1759.

The Sextant gets its name from the Latin word for 'a sixth' because it is a sixth of a circle (60 degrees) and can measures angles of up to 120 degrees.

The Quintant is similar to the more common and well known Sextant, it is used in the same way but the Quintant has the ability to measure larger angles than the Sextant.

The Quintant gets it's name from the Latin word for 'a fifth' because it has an arc equivalent to one-fifth of a circle (72 degrees). Due to the doubling effect of the two mirrors this means it can measure angles of up to 144 degrees.

The Octant preceeded the design of the Sextant and it was invented by John Hadley and Thomas Godfrey simultaneously in 1731.

The Octant gets its name from the Latin word for 'a eighth' because it is an eighth of a circle (45 degrees) and can measures angles of up to 90 degrees.

In the early days the instrument frames were made from wood, usually Ebony with Ivory scales, however in the later years of Octant production the frames were made from brass and the scales were either Ivory or silver.