Item Information

Dimensions (mm) not provided
Weight (carats) not provided
Certified Gemstone



Antique captains personal Navigational instrument. 22k yellow gold plated

    Weight:  272 Grams
   Size        100mm width X 110 Lenght { approx }
   Thickness: 50mmm
   Maker or vessel name:  Ross  London
   Box type hand made wooden with hand made metal Anchor monogram punched on wooden plank.
   Box size:   150 x 135mm (approx}


This original Ross London sextants was made in England at the end of the 18th century. The biggest problem for sailors in the 18th century was finding their position in the middle of the oceans during long journeys. Sailors needed to be able to find both their latitude (which was their position north or south on the earth) and their longitude (which was their position east or west on the earth). Sextants helped them to find out both of these things. Before the invention of satellites and electronic satellite navigation systems it was very hard for sailors to find their position at sea. Many shipwrecks occurred because captains got the positions of their ships wrong. This not only caused the deaths of many seamen but also had big political and economic implications for the government because lots of battles happened at sea or valuable cargo could be lost in shipwrecks.

Sextants are made with a circular curve that is one sixth of a circle. The curve is divided up like a protractor. It is used for measuring angles so it is labelled with degrees. The other important parts of a sextant are a telescope, a piece of glass which is half see-through and half mirror (called the horizon glass), and a moving arm which has another mirror fixed to it.

 In earlier times, marine sextants had a fixed telescope leveled on the horizon and a radial arm is moved against an arc scaled in degrees. The radial arm is adjusted to get the reflection, of a known star, from index mirror and then off the horizon mirror down the telescope until it lines up with the horizon. The position of the radial arm on the scale gives the stars elevation. The nautical sextant range includes: slow motion nautical sextant, octants, slow motion nautical sextants and round dubble telescope nautical.

In modern navigation sextants, the light ray from the celestial body is reflected in two mirrors (in series) one of which is adjustable and the other is half silvered. By rotating one mirror and its attached index bar, the image of the body is brought down to the horizon. The rotation measures the altitude on the limb.





 mm = 1/4 inch (Approx)

$3,300.00 USD

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Pricing & Details

Auction ID 245012
Watchers 7 watching
Viewed 10,235 times
Starts 24th Oct 2011 4:39pm PDT

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