Education
The Light Source
Our shores are littered with the wrecks of ships that have gone down on numerous reefs over the centuries. Thousands of years ago, open fires were used to warn sailors of their dangers and the first recorded lighthouse was built in the third century BC at Alexandria in Egypt. At the top of its 140m tall tower a wood fire was kept burning in a metal brazier; later, the fires were enclosed but would still have needed close supervision.The first offshore lighthouse in Europe was built on the dangerous Eddystone Rock, 13 miles south west of Plymouth by an eccentric gentleman called Henry Winstanley in 1698. Unfortunately, five years later it, and Henry, were destroyed in a terrible storm.
Smeaton's tower, the third Eddystone lighthouse, which was built in 1759 used a total of 24 candles mounted in a chandelier arrangement. Incredibly, this provided enough light to make it visible five miles away.
Keeping alight any open wood or coal fire, or Smeaton's candles, would have been very difficult. It was not until 1782 that oil was first used as an energy source and lighthouse keepers had to wait until the early twentieth century before reliable gas burners became standard, thanks to an ingenious invention of Gustaf Dalen.
A black metal rod was suspended vertically and connected to the gas supply. As it absorbed the sun's heat energy, the rod expanded downwards, cutting off the supply during the day. This was known as a 'sun-valve'.
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