A Sextant 

This object was designed for used by sailors to work out where they were out at sea. If you know where you are, you can work out how to get to your destination!

Before the invention of modern navigation equipment, sailing ships needed to know two things to work out their position- how far north/south they are and how far west/east they were. This information provides the coordinates for their position on the Earth. Kiplin Hall and Gardens, where the sextant is kept, has the coordinates 54^o22’19.32”N  1^o34’44.36”W.

The north/south position is called latitude and can be worked out using the sextant. If you look carefully at the object you can see it has mirrors and pieces of glass in the top part. The bottom part is curved and has a number scale on it. It is used to measure the angle between the sun and the horizon.

At midday the sun is at its highest in the sky. The further you are away from the equator the lower the sun will be compared to the horizon. If you know how high the sun is at midday you can work out how far north you are. The sextant does this by lining up two images, the horizon and the sun, when you look through the telescope part. When you adjust the sextant to make the images line up, you can read the angle of the sun in the sky from the curved scale.

The problem is if you only know how far north you are, you could be anywhere east to west. York has the same latitude as Edmonton in Canada. To work out your west/east you need to know the time… you need a marine chronometer.

A Marine Chronometer

A marine chronometer is a clock that works on a ship. This chronometer came from the company Dent, in London, which has a royal warrant and had supplied the royal family.

If you look carefully at the object you can see that the clock is mounted on some metal rings called a gimbal. This allows the clock to stay steady even in rough seas so that it can work smoothly and keep good time.

Greenwich was chosen as the site for a Royal Observatory in 1674. It became the point where all west/east points were measured. We call the east/west position longitude.

When ships sail around the Earth, the sun rises and sets at different times from those at home. This is because the Earth is spinning which makes the sun seem to rise and set. The times of rising and setting depend on where you are on the globe.

If you know what the time is in Greenwich, London, you can compare the position of the sun in the sky where you are, to where it would be in the sky if you were in Greenwich. For example if midday was 12 hours later in your position than in Greenwich, you would be exactly on the other side of the world!

Sailors needed a really accurate clock that didn’t lose or gain time. The marine chronometer was designed to do that. If it went wrong, the captain wouldn’t know the time in Greenwich and so wouldn’t be able to work out his longitude – he would be lost. This chronometer is engraved with name Captain W.C. Talbot and the name of the Royal Navy ship, H.M.S Steady. But the story doesn’t end there… 

Explore HMS Fawn 

What did Captain Walter Talbot’s ship look like? We don’t have an image of HMS Fawn from 1864 when Talbot was captain and when the marine chronometer was very likely used, but we do have some artists’ impressions from slightly earlier that decade and a few years later.

Firstly, from 1862 you can see HMS Fawn and HMS Miranda taking part in a regatta, by F R Slack (artist) and Day and Son (engravers), from the National Maritime Museum collection.

In 1880, HMS Fawn was also shown caught in a squall by artist Richard Brydges Beechey, painted in oil on canvas. Beechey joined the Royal Navy aged 14 and, like other members of his family, became a celebrated painter, specialising in naval scenes and painting ports. This painting of HMS Fawn was one of a series of paintings representing actions and commands of its captain, the future Admiral Ralph Peter Cator (1829–1903).