Marine engineering

Aberdeen had a tidal harbour at the time Abernethy arrived, and he spent a year dredging and building embankments to improve the access channel. In the following year, a competition was held for the design of an enclosed dock, and his design was selected. An Act of Parliament was obtained to implement the design, but Abernethy first had to convince an independent assessor in London of its soundness. The meeting was inconclusive, but the chairman of the Harbour Trustees was satisfied, and tenders were sought for construction. The lowest tenderer was given the contract, but could not complete it, and Abernethy took over after a year, using direct labour to finish the work. When it was built, the entrance lock was the largest in Britain, measuring 250 by 60 feet (76 by 18 m), with a navigable depth of 22 feet (6.7 m) at high water.^[2]

The Preliminary Enquiries Act was passed to ensure that major new schemes were competently assessed before being implemented, and Abernethy worked as one of its Surveying Officers for eight years until 1852. During this time he held public enquiries into schemes for improvements to the River Clyde, the River Tyne and the River Ribble, and for the construction of docks at Belfast, Birkenhead, Glasgow, Liverpool and Newcastle upon Tyne. In addition to obtaining skills in the conduct of such meetings, he met with the leading engineers of the time, and learned the best practices for marine engineering. He acted as a consultant to the Swansea Harbour Trustees from 1847, and became their Engineer-in-chief in 1849, but continued to live in Aberdeen until 1851, when he moved to Birkenhead, where he held the same post as well.^[2]

He produced plans for Birkenhead Docks, as he was not convinced that the rival plans, produced by James Rendel, were practicable. Both plans were assessed by Admiral Sir Francis Beaufort and Robert Stephenson, who found in favour of Rendel. Following a takeover by Liverpool Corporation in 1855, Rendel's plans were implemented, but the sluices failed soon after the docks were completed in 1864. A new Act of Parliament obtained in 1866 authorised the rebuilding of the docks to Abernethy's plans. Throughout this period he was active with other schemes as well, including a shipyard for Messrs. Laird on the River Mersey. He produced plans for improvements to the Irish Bann Navigation in 1851, and for the Dean Forest, Monmouth, Usk and Pontypool Railway in the following two years.^[3]

Consulting engineer

He set up an office in London in 1853, and acted as consulting engineer for a large number of schemes, while still maintaining his regular oversight of the docks at Cardiff, Fraserburgh, Newport and Swansea. He expanded his work to include overseas projects in 1862, although a number of his recommendations were not implemented, and the scheme that was eventually built at Alexandria harbour was rather less satisfactory than his own design.^[3] Major harbour schemes included those at Silloth, Portpatrick, Falmouth, Port Natal in South Africa, Watchet, Boston and the Alexandra Dock at Kingston upon Hull. He also worked on the Swansea and Neath Railway between 1862 and 1863, the Turin and Savona Railway in Italy, which was 120 miles (190 km) long and included a 4-mile (6.4 km) tunnel, and the Hayling Island Railway. Between 1862 and 1867, he was responsible for the Grand Canal Cavour, a 54-mile (87 km) irrigation canal, which entailed him visiting Italy every four months. He used the opportunity this presented to visit Venice several times. In 1883, he reported on the three rival schemes for the Manchester Ship Canal, finding in favour of the one by Sir Edward Leader Williams. He acted as consulting engineer, visiting the site every month between 1885 and 1893,^[4] while Williams was Engineer-in-chief.^[5] His last major scheme overseas was the reclamation of Lake Aboukir in Egypt, between 1888 and 1889, although his regular dock work in Britain continued until his death, and work on the Bute Dock at Cardiff was still in progress when he died. It was completed later that year.^[4]