John Smeaton (8 June 1724 – 28 October 1792) was an English civil engineer responsible for the design of bridges, canals, harbours and lighthouses. He was also a capable mechanical engineer and an eminent scholar, who introduced various scientific methodologies into engineering. Smeaton was the first self-proclaimed "civil engineer", and is often regarded as the "father of civil engineering". He pioneered the use of hydraulic lime in concrete, using pebbles and powdered brick as aggregate. Smeaton was associated with the Lunar Society.
Smeaton was born in Austhorpe, Leeds, England. After studying at Leeds Grammar School he joined his father's law firm, but left to become a mathematical instrument maker (working with Henry Hindley), developing, among other instruments, a pyrometer to study material expansion. In 1750, his premises were in the Great Turnstile in Holborn.
He was elected a Fellow of the Royal Society in 1753 and in 1759 won the Copley Medal for his research into the mechanics of waterwheels and windmills. His 1759 paper "An Experimental Enquiry Concerning the Natural Powers of Water and Wind to Turn Mills and Other Machines Depending on Circular Motion" addressed the relationship between pressure and velocity for objects moving in air (Smeaton noted that the table doing so was actually contributed by "my friend Mr Rouse" "an ingenious gentleman of Harborough, Leicestershire" and calculated on the basis of Rouse's experiments), and his concepts were subsequently developed to devise the 'Smeaton Coefficient'. Smeaton's water wheel experiments were conducted on a small scale model with which he tested various configurations over a period of seven years. The resultant increase in efficiency in water power contributed to the Industrial Revolution.
Over the period 1759–1782 he performed a series of further experiments and measurements on water wheels that led him to support and champion the vis viva theory of German Gottfried Leibniz, an early formulation of conservation of energy. This led him into conflict with members of the academic establishment who rejected Leibniz's theory, believing it inconsistent with Sir Isaac Newton's conservation of momentum.
In his 1759 paper "An Experimental Enquiry Concerning the Natural Powers of Water and Wind to Turn Mills and Other Machines Depending on Circular Motion" Smeaton developed the concepts and data which became the basis for the Smeaton coefficient, the lift equation used by the Wright brothers. It has the form:
{\displaystyle L=kV^{2}AC_{l}\,}
is the Smeaton coefficient (see note below)
is the lift coefficient (the lift relative to the drag of a plate of the same area)
The Wright brothers determined with wind tunnels that the Smeaton coefficient value of 0.005 was incorrect and should have been 0.0033. In modern analysis, the lift coefficient is normalised by the dynamic pressure instead of the Smeaton coefficient.
Smeaton is important in the history, rediscovery of, and development of modern cement, identifying the compositional requirements needed to obtain "hydraulicity" in lime; work which led ultimately to the invention of Portland cement. Portland cement led to the re-emergence of concrete as a modern building material, largely due to Smeaton's influence.
Recommended by the Royal Society, Smeaton designed the third Eddystone Lighthouse (1755–59). He pioneered the use of 'hydraulic lime' (a form of mortar that will set under water) and developed a technique involving dovetailed blocks of granite in the building of the lighthouse. In designing the lighthouse, Smeaton combined different types of knowledge from separate fields, including geology, electrical research, meteorology, and classical learning.
His lighthouse remained in use until 1877 when the rock underlying the structure's foundations had begun to erode; it was dismantled and partially rebuilt at Plymouth Hoe where it is known as Smeaton's Tower. In 2020 a Cornish granite bust of Smeaton by Philip Chatfield, commissioned by The Box, Plymouth, and funded by Trinity House, was installed in the tower's lantern chamber before its reopening. The bust is based on a plaster one donated by the Institution of Civil Engineers in about 1980, but later removed for safety reasons.
Deciding that he wanted to focus on the lucrative field of civil engineering, he commenced an extensive series of commissions, including:
the Calder and Hebble Navigation (1758–70)
Coldstream Bridge over the River Tweed (1763–66)
Improvements to the River Lee Navigation (1765–70)
Smeaton's Pier in St Ives, Cornwall (1767–70)
Perth Bridge over the River Tay in Perth (1766–71)