Henry Marc Brunel’s Quintant, Aabout 1830

• This small silver quintant belonged to Isambard Kingdom Brunel’s second son Henry Marc Brunel. Like his father, Henry was an engineer; he worked on a wide range of projects including Tower Bridge in London.
• The quintant is kept in a wooden box with a brass plaque on the lid engraved with “HM Brunel”. The quintant was made by the instrument manufacturer Cary in London around 1830, twelve years before Henry Brunel was born. It is believed to have been left to Henry by his father following his death. In Isambard Kingdom Brunel’s will it states that all his engineering equipment and publications were to be given to Henry.
• For Victorian engineers, like Henry Brunel, a quintant would have been a useful piece of equipment. When looking at an area of land on which to construct a bridge, tunnel or railway, the quintant could be used to measure the angular distance between two points. This information would help the engineer decide if the land was suitable to be built on.
• Isambard Kingdom Brunel could have used a quintant, like this one, as he tried to find the flattest route for the Great Western Railway between Bristol and London.

Henry Marc Brunel – Engineer

Born in June 1842, Henry Marc Brunel was the second child of Isambard Kingdom Brunel and Mary Horsley. Like his father and grandfather, Sir Marc Brunel, Henry became an engineer. Isambard was keen for his son to follow in his footsteps and encouraged him in his profession.

Henry spent several years as an apprentice for a few different engineers, including Sir John Hawkshaw, who was one of two engineers to finish building the Clifton Suspension Bridge in Isambard Kingdom Brunel’s memory. Like his father, Henry worked on a range of different types of projects, including tunnels, bridges and railways. In 1866 he was involved in a plan to build a tunnel under the English Channel to link England and France. Henry learnt about geology so that he could help with the initial stages of the project, but it was abandoned before any part of the tunnel was dug.

Henry Brunel also designed a ship, the SS Chauncy Maples which, like the SS Great Britain, was a steamship with a screw propeller. She is still afloat today though her steam engine was replaced with a diesel engine in 1967.

Later in life, Henry worked alongside his older brother, Isambard Junior, to write books about their father and help to protect Isambard Kingdom Brunel’s legacy.

Not lost at sea

You may not have heard of a quintant before, but you might have heard of a similar instrument called a sextant. It is used to measure angles to help with navigation at sea.

Imagine you’re on a ship in the middle of the ocean, how can you find out exactly where you are? Nowadays you might use a map on a mobile phone which relies on a global positioning system (GPS), a series of satellites orbiting the Earth, to pinpoint exactly where you are.

Now imagine you’re on the SS Great Britain in the 1850’s sailing to Australia, how can you work out where you are? GPS won’t be invented for another hundred and twenty years! The crew on the SS Great Britain had to rely on a range of different instruments and maths to help them. In the middle of the ocean, with no obvious landmarks, crew used compasses, sextants and the sun to help them plot their position on maps and keep the ship sailing in the right direction. A sextant, similar in design to a quintant, was used to measure the angle of the sun above the horizon. This angle and the exact time the measurement was taken was used to calculate the ship’s latitude and longitude, which could then be used to pinpoint the ship’s exact location on a map.

At night, without the sun, navigation became harder; however, the sextant could still be used, with the crew relying on the North Star and moon for their calculations rather than the sun.

Sextants are an incredibly reliable piece of equipment because they do not need electricity or satellites to work. Some modern ships still carry one in case their more modern methods of navigation fail.

• Make your own simple paper sextant and use it to calculate your latitude.
• Find out about creative people like Henry and Isambard Kingdom Brunel, with this Brunel-themed Arts Award Discover logbook.
• Learn more about the challenges faced by Isambard Kingdom Brunel when designing the Great Western Railway by taking a close look at his Drawing Set and Dessert Stand.
• Find out more about this object and others like it in our online Collection.