A Narrative of the Eddystone Lighthouse

SUBJECT AREA: Civil engineering, Mechanical, pneumatic and hydraulic engineering, Steam and internal combustion engines

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As a boy, Smeaton showed mechanical ability, making for himself a number of tools and models. This practical skill was backed by a sound education, probably at Leeds Grammar School. At the age of 16 he entered his father's office; he seemed set to follow his father's profession in the law. In 1742 he went to London to continue his legal studies, but he preferred instead, with his father's reluctant permission, to set up as a scientific instrument maker and dealer and opened a shop of his own in 1748. About this time he began attending meetings of the Royal Society and presented several papers on instruments and mechanical subjects, being elected a Fellow in 1753. His interests were turning towards engineering but were informed by scientific principles grounded in careful and accurate observation.

In 1755 the second Eddystone lighthouse, on a reef some 14 miles (23 km) off the English coast at Plymouth, was destroyed by fire. The President of the Royal Society was consulted as to a suitable engineer to undertake the task of constructing a new one, and he unhesitatingly suggested Smeaton. Work began in 1756 and was completed in three years to produce the first great wave-swept stone lighthouse. It was constructed of Portland stone blocks, shaped and pegged both together and to the base rock, and bonded by hydraulic cement, scientifically developed by Smeaton. It withstood the storms of the English Channel for over a century, but by 1876 erosion of the rock had weakened the structure and a replacement had to be built. The upper portion of Smeaton's lighthouse was re-erected on a suitable base on Plymouth Hoe, leaving the original base portion on the reef as a memorial to the engineer.

The Eddystone lighthouse made Smeaton's reputation and from then on he was constantly in demand as a consultant in all kinds of engineering projects. He carried out a number himself, notably the 38 mile (61 km) long Forth and Clyde canal with thirty-nine locks, begun in 1768 but for financial reasons not completed until 1790. In 1774 he took charge of the Ramsgate Harbour works.

On the mechanical side, Smeaton undertook a systematic study of water-and windmills, to determine the design and construction to achieve the greatest power output. This work issued forth as the paper "An experimental enquiry concerning the natural powers of water and wind to turn mills" and exerted a considerable influence on mill design during the early part of the Industrial Revolution. Between 1753 and 1790 Smeaton constructed no fewer than forty-four mills.

Meanwhile, in 1756 he had returned to Austhorpe, which continued to be his home base for the rest of his life. In 1767, as a result of the disappointing performance of an engine he had been involved with at New River Head, Islington, London, Smeaton began his important study of the steam-engine. Smeaton was the first to apply scientific principles to the steam-engine and achieved the most notable improvements in its efficiency since its invention by Newcomen, until its radical overhaul by James Watt. To compare the performance of engines quantitatively, he introduced the concept of "duty", i.e. the weight of water that could be raised 1 ft (30 cm) while burning one bushel (84 lb or 38 kg) of coal. The first engine to embody his improvements was erected at Long Benton colliery in Northumberland in 1772, with a duty of 9.45 million pounds, compared to the best figure obtained previously of 7.44 million pounds. One source of heat loss he attributed to inaccurate boring of the cylinder, which he was able to improve through his close association with Carron Ironworks near Falkirk, Scotland.

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