Lord Macclesfield at once advised him to consult Smeaton.
After carefully studying the two previous designs, Smeaton decided to construct a new lighthouse of stone. He drew out his design, following to some extent the form which had been adopted by Rudyerd, but greatly strengthening the base. In March 1756 he paid his first visit to the reef, and after a thorough examination of it, which was rendered extremely difficult by the constant gales, he completed his plans. A model was made of the entire structure, in which his ingenious system of dovetailing together the blocks of stone in the various courses was clearly indicated. This model is now in the possession of Mr. Oliphant Smeaton of Edinburgh, but is to become the property of Trinity House. Smeaton's design was at once accepted by the proprietors and by the Trinity brethren.
The work was begun on 3 Aug. 1756, when Smeaton himself fixed the centre of the work. The rest of the season until November was spent in cutting out the dovetail recesses in the foundation rock. It was decided to use Portland stone. The following winter was spent in preparing the stones in the yard at Plymouth, every stone being set out carefully on a large floor, and then accurately dressed to its true form. Work was begun again on the reef on 12 June 1757, when the first stone was fixed in place, and by the end of the season nine courses were complete; in 1758, in spite of constant interruptions, the work was raised to the twenty-ninth course, and in 1759 it was finally completed, and the light was exhibited for the first time on 16 Oct. 1759. The main stone column was 70 feet high, with a diameter of 28 feet at the base and 15 feet under the corona which formed the top course. The lantern, with its ball, rose to a further height of 28 feet. Twenty-four candles, carried in a chandelier, formed the light (oil lamps were found to be troublesome, from the smoke they deposited on the glass of the lantern), and on a clear night the light was plainly visible from the Hoe at Plymouth. This splendid work stamps Smeaton as an engineer of the first order. It remained for more than a century a monument of his genius and constructive skill, resisting all the furious storms which beat upon it until 1877. In that year, in consequence of the undermining of the portion of the reef on which it stood, it was decided by the Trinity board that a new lighthouse must be erected on another portion of the reef. This was completed in 1882; the upper rooms of Smeaton's building were then carefully taken down and re-erected on Plymouth Hoe on a granite frustum, which was a model of the solid base of the old lighthouse. That base was left standing as a memorial on the reef.
After the completion of his lighthouse, Smeaton's skill was generally recognised. He was employed on numerous reports on drainage and canal schemes, but, owing to lack of money and the general apathy, few of his schemes were carried out.
In bridge-building his chief work was in Scotland. There he constructed three handsome arched bridges, still standing, at Perth, Banff, and Coldstream respectively. Their main features were the segmental arches, and the circular perforations over the spandrels. His only bridge in England, over the Tyne at Hexham, was completed in 1777, but, owing to the defective foundations of the piers, was swept away in a severe flood in 1782. After the fall of the newly constructed North Bridge, Edinburgh, in 1769, Smeaton was consulted as to the strengthening of it. He gave such advice regarding the shape of the foundation-buttresses—which he considered should be on a principle analogous to that of the Eddystone—as enabled the architect to erect the structure in a manner so stable as to last until 1896, when increasing traffic rendered the construction of a wider bridge an absolute necessity.
Another great work which Smeaton carried out in Scotland was the Forth and Clyde canal. This was begun in 1768, and was the most important engineering work of that kind which had been executed in Great Britain up to that date. Smeaton's canal followed very closely the line of the old Roman wall of Antoninus. It was thirty-eight miles in length, had thirty-nine locks, and a rise of 156 feet to the summit level, with a depth of water of six feet. Unfortunately, owing to financial difficulties, it was not completed till 1790. Smeaton was also responsible for a number of harbour works. In 1774 he was called in to take charge of the Ramsgate Harbour scheme, which he brought to a successful completion.
Most of his life subsequent to his marriage, in June 1756, was spent at his home at Austhorpe, where he built a detached four-storied tower, which was fitted up as his workshop and study. As late as 1787 he took out a patent (No. 1597) for a machine for extracting oil from seeds. During his frequent visits to London on parliamentary and other business he founded, in 1771, a small club of engineers (‘The Smeatonian’), which met on Friday nights at the Queen's Head Tavern, and was eventually merged in