The lamp at Souter Lighthouse, a design marvel
Souter Lighthouse in South Shields was a technological and design marvel of its age and demonstrates the most advanced lighthouse engineering of its day. Built in 1871, it was the first purpose-built electric powered lighthouse in the world.
Souter Lighthouse stands on the coastline midway between the Tyne and the Wear. Before the lighthouse was built in 1871, this coastline was the most dangerous in the country due to the high number of ships that were wrecked on the treacherous reefs of Whitburn Steel.
Unlike most lighthouses of the time, which used gas and oil lamps, Souter was the first lighthouse in the world built to be powered by electricity. The beam flashed a red light for one second every five seconds. The lighthouse itself is no longer operational today. But the tower and lamp can be visited and explored and it's possible to see the light in action and hear the foghorn on special occasions.
The lens: an object of beauty and innovation
The light that shone from the lighthouse relied on a powerful biform lens lamp construction (comprising an upper and lower lens) made of glass, iron and mercury. Seeing the the lamp close-up, with its primary coloured screens and grid-like lines, is more akin to admiring a Mondrian painting!.
The total weight of the lens is an astonishing 4.5 tonnes and it floats on 1.5 tonnes of mercury. The upper lens employs a 500 watt lamp, the lower lens a 3,500 watt lamp and the total candle power is 1,380,000. The light bulbs were changed after 3,000 hours, or eight months, of use.
The powerful light is produced by a 4.5 tonne rotating biform First Order optic. The lens was installed in 1915 and is made up of 1,008 prisms of glass, making a powerful Fresnel lens. The light would be seen for 20 miles off shore, with a distinct red colour distinguishing it from neighbouring lighthouses.
At the base of the lighthouse is a column which houses the weights which operated the clockwork mechanism for turning the lens. The weights were wound by hand to the top of the lighthouse every 1¼ hours. The winding process took 10 minutes. The clockwork mechanism was used until the 1970s when it was replaced by an electric motor.
Pioneering use of ‘wasted' light
Souter was built to make use of the ‘wasted' light’ that shined landward - a pioneering design. A series of prisms directed the excess light to the room below, shining it south over Sunderland Harbour to warn of dangerous rocks to the South of the harbour. If sailors were in direct line with the rocks the light shined red; if they were clear of the rocks the light shined white.
This light is located on the Half Way Landing, six metres below the main lens. The light had a range of six miles and was divided into two sections: seaward (the white section which showed a white light) and landward (the red section which showed a red light due to a red screen being fitted to the landward section of the lens).
Ships approaching Sunderland from the south would locate the white light. Keeping the white light in view they would sail inside the white sector until they were opposite the harbour entrance when they would turn westward and sail into harbour.
If the ship strayed off course (landward) into the red section they would lose sight of the white light and the red light would be seen warning them that they were running into danger.
From past to present
With the development of new technology like GPS and satellite navigation, the lighthouse was decommissioned in 1988 after 117 years of service to shipping in the North East.
Now in the care of the National Trust, you can visit the lighthouse and climb the 76 steps to the top of the tower, getting up close to the lamp itself and taking in the amazing view of the Leas. The surrounding area is rich in history and wildlife.
On special occasions, the team who look after Souter are able to show the light in action and sound the foghorn.