Solid brass, six shaded lenses of varying intensity, and a powerful telescope.
The Full-Size Sextant is fully functional, but not intended for modern blue-water navigation.
At an early age he was bound apprentice to the master of a coasting vessel, and is said to have entered the navy by offering himself in exchange for the mate of this vessel, who had been pressed.
After serving three years in the Blenheim, Torbay, and Russell, he was, in 1740, appointed to the Centurion, and sailed in her round the world with Commodore Anson, as midshipman, master's mate, and master.
On his return home be passed the examination for lieutenant, and his certificate, dated 8 Jan.
1744-5, says that he 'appears to be more than twenty-four years of age.' Through Anson's interest he was very shortly afterwards made a lieutenant, then commander, and was advanced to post rank on 28 Nov.
1747, and appointed to the Bellona frigate, which he commanded with some success till the peace.
By Mary Bellis Weights and measures were among the earliest tools invented by man.
Primitive societies needed rudimentary measurement tools for many tasks: constructing dwellings of an appropriate size and shape, fashioning clothing, or bartering food or raw materials.
Among the earliest length measures was the foot, which varied from place to place For example, three different Greek standards are known: the Doric foot, the Attic foot and the Samian foot.
There were two common sizes for a "foot" - the foot of 246 to 252 mm based on a man's bare foot - the foot of 330 to 335 mm based on two hand measurements.
The first calibrated foot ruler, a measurement tool, was invented in 1675 by an unknown inventor.
Our full-size replica Vernier Sextant is dedicated to Royal Navy Captain John Campbell, who developed the instrument in 1757.
It appeared at a crucial moment, at about the same time that the first accurate, portable chronometer was developed.