The Life and Works of John Rennie (7 June 1761 – 4 October 1821)

Bell Rock Lighthouse

Prof/Dr Roland Paxton MBE FICE FRSE

Scotland’s Bell Rock Lighthouse ranks as one of the greatest civil engineering maritime achievements. The lighthouse, erected from 1807-11 in the North Sea, about 12 miles off Arbroath, was built of stone quarried at Aberdeen, Mylnefield [Dundee] and Craigleith [Edinburgh] and shipped to Arbroath [Fig.1]. Exceptional difficulties in creating the lighthouse arose from the rock being inundated with up to 14ft [5m] of water every high tide [Fig.2], at times subject to the awesome force of the sea. This situation severely restricted working time at the rock before the temporary barrack adjoining the tower became operational. But, with ingenuity, determination, and courage, this seemingly impossible challenge was met, to achieve an elegant lighthouse, 115ft [35m] tall with a 42ft [13m] diameter base, costing £61,331.9s.2d. [Stevenson 1824, 483]. During the next half century, the project influenced lighthouse, harbour and bridge construction techniques. Its success also enabled Robert Stevenson in 1811 to set up a family engineering firm which practiced for 151 years and achieved an international reputation.

Fig.1 Lecture 10, 4

In 1799; 70 vessels were stranded or lost within 30 miles or so of the rock, many of which might have been saved by a lighthouse. Stevenson, then apprenticed to and in charge of the lighthouse work of lamp manufacturer Thomas Smith, Engineer to the Northern Lighthouse Board, proposed and modelled a stone lighthouse. From 1800-06 this proposal formed the basis of applications for the Act of Parliament necessary for its execution, which was eventually obtained on 21stJuly 1806 with the support of the experienced Rennie, who had just reported on the feasibility of Plymouth breakwater, pier, and two lighthouses he estimated at £1.17m for which he was to became the engineer. On 3rd December, the Lighthouse Board resolved that the lighthouse be erected ‘under Rennie’s direction’ and appointed him ‘Chief Engineer and Stevenson as his ‘Assistant’. In February 1807 Rennie produced his basic tower elevation and furnished Stevenson with details for setting out the cycloidal curved face he considered essential for its stability in gales. [Paxton Dynasty 2011, 82]. Rennie’s plan and elevation were published in the Scots Magazine for June 1807 {Fig. 3. Note the sea being deflected upwards at the curved face].

Fig.2 Lecture 9, 5. The railway is high-lighted in purple.
Fig.3 Rennie’s Lighthouse elevation Feb.1807 R.Scott sculpt for A. Constable, Edinburgh

Under Rennie’s direction the as built form of the lighthouse developed significantly from Stevenson’s 1800-06 proposal [Fig.4]. The Clerk-of-Works, David Logan, who later became a chief engineer wrote, ‘that if Stevenson’s design had been built not one stone would have been left standing. It was not dovetailed … there was no lateral connection and the profile had not the curvature for breaking up the waves’. We shall never know, but this was the fate of Stevenson’s 36ft [11m] Carr Rock tower beacon in 1817. In a simulation at my RSE lecture it fell against 5m waves [Paxton A grand design – Lecture 10, 39]

Fig.4 Lecture 10, 10

On 24 September 1809 Rennie inspected the tower [Fig.5] and reported that ‘the curve of the outside tower answers fully to every expectation I had formed of it, the sea plays round it and I trust it will be found when finished the compleatest work of its kind.’ [Paxton Dynasty 2011,73].

Fig.5 Lecture 9, 19

Rennie insisted on dovetailing [Fig. 6] and furnished several sketches of alterations to David Logan, including ‘the courses undovetailed at the centre which were adopted by Mr Stevenson but afterwards rejected (by Rennie)’[Paxton Dynasty 2011, 77]. Rennie seemed aware that Smeaton would probably have formed a similar curvature at Eddystone if its rock had been larger.

Fig 6 Lecture 9, 15
Fig. 7 Lecture 9, 10
Fig. 8 Lecture 10, 35
Fig.9 Lecture 9, 6

On 1st February 2011 its light became operational, and nature tested the tower with a gale. Spray rose to about 70ft [21m] and ’the sea was covered with foam as far as the eye could reach’ [Stevenson 1824, 407]. It is a wonderful tribute to all concerned that the lighthouse, with lts nominal range of 28 miles, automated in 1988, is still in service. In 1996 a BBC 2 documentary rightly dubbed it as one of Seven Wonders of the Industrial World along with Brooklyn Bridge, the Panama Canal and Hoover Dam.

The credit for lighthouse’s design and erection has been generally attributed by posterity to Stevenson, not Rennie. Up until 1848, each of their sons believed their respective fathers due this merit and their families disputed the matter until recently. The publication of my research findings [Paxton Dynasty 2011] only became possible after I was able to compare the contemporary records of both engineers in the National Library of Scotland. This led to the surprising discovery that some key letters indicating Rennie acting with the authority of a chief engineer had been cut out of the Stevenson letter books, possibly in the mid-19th century, and also, that Rennie’s key report on the implementation of his design had been, almost certainly, deliberately omitted from the account of the lighthouse [Stevenson 1824] published after Rennie’s death, and which scarcely mentions him. These facts are consistent with Rennie’s belief in March 1814 that Stevenson was about ‘to assume the whole merit for the Bell Rock Lighthouse’ [Paxton Dynasty.2011, 79]. These factors resulted in many later writers being unaware of Rennie’s essential role, even Robert Louis Stevenson and D. Alan Stevenson in The World’s lighthouses before 1820! My findings in [Dynasty 2011] attracted a full-page review by Mark Macaskill in The Sunday Times on 6th Feb. 2011 headed, ‘Forgotten lighthouse hero hailed at last’ emphasizing Rennie’s role and that both engineers ‘played their part in creating a wonder of the modern world’. James Will, the great, great, great, grandson of Robert Stevenson, welcomed my research and commented that the ‘contribution through this new book is very valuable’. My old friend, the late James Rennie, for whom I organized a visit to the lighthouse, would have been delighted to see this modern recognition of his forebear’s key input as Chief Engineer. Hopefully this contentious dispute now rests!

From my review of contemporary obituary notices of Rennie [Paxton 2011], it seems appropriate to conclude with that of the eminent French engineer, Charles Dupin. He wrote in 1821 that on the Bell Rock reef ‘Mr Rennie has built the most beautiful lighthouse which closely compares with Eddystone being of similar shape and competing with its audacity and greatness. Mr Stevenson was the able engineer who executed the lighthouse under Mr Rennie’s direction’ [Paxton, 2011, 7,10-11].

References and further reading

Stevenson, R. An Account of the Bell Rock Lighthouse. Edinburgh 1824. Includes Rennie’s reports of 1805, 1806, 1807, 1808, but not that of Oct 1809 directing operations following his visit on 24th September, now printed in Dynasty of Engineers 2011.

Paxton, R ‘Account of a visit to the Bell Rock Lighthouse on 19th– 20th August 1986’. ICE PHEW Newsletter 1986. 32, 4-10.

Paxton, R.A. ‘An assessment of aspects of the work of the Stevenson engineers’. Ph.D. thesis. Heriot-Watt University 1999, 20-27. Includes an assessment of the roles of Rennie and Stevenson’s in creating Bell Rock lighthouse.

Paxton R. & Shipway J. Civil Engineering Heritage Scotland Highlands and Islands. Thomas Telford Publishing, London, 2007 – ‘Bell Rock Lighthouse’ 51-54.
Paxton, R. Dynasty of Engineers – The Stevensons and the Bell Rock. Northern Lighthouse Heritage Trust, Edinburgh, 2011. Includes the first printing, with illustrations, of Rennie’s previously unpublished key report of October 1809 with notes.

Paxton, R. John Rennie, Civil Engineer. Contemporary Biographical Notices reprinted on the 250th anniversary of his birth. School of the Built Environment, Heriot-Watt University, Edinburgh, 2011

Paxton, R. ‘A grand design. Creation of the Bell rock Lighthouse 1807-11’. A presentation at the Royal Society of Edinburgh on 4th February 2011, for the bicentenary of the first light becoming operational. From ICE Scotland Museum Lecture 10.

Paxton, R. ‘Achieving the seeming impossible – Bell Rock railway’. R&CHS’s Early Railway Conference. 2014. From ICE Scotland Museum Lecture 9.

Institute for Infrastructure and Environment, Heriot Watt University, Edinburgh. 5 August 2021