with a navigable depth of at spring tides, the entrance lock was also one of the largest ever built. By the time it was completed, the original estimated cost of £290,000 had risen to £611,000, and although some of this was caused by problems with unstable soil in both the new cut and in the basins, much of the extra cost can be attributed to a series of improvements made as the project progressed. The younger Jessop was solely responsible for the design of the Prince's Bridge, a swing bridge over the entrance to the harbour. This required him to submit estimates to Parliament, and give evidence to support the project to the House of Lords. The bridge was completed at the same time as the main project in May 1809, having cost £14,300. Jessop continued to work for Bristol Harbour until late 1810, overseeing various jobs, including the purchase of a steam dredger. At the end, the Directors expressed their complete confidence in his abilities, stating that he had "acquitted himself in the important trust reposed in him with the most unsullied reputation and honour". Consulting engineer Now aged 30, and with his abilities as an engineer acknowledged, he became an independent consulting engineer. In 1811 he surveyed the route for a canal linking Godalming on the River Wey Navigation to Newbridge on the River Arun. Following the issuing of a report in August and a prospectus in October, he re-surveyed the route, and in May 1812 suggested a revised route, at an estimated cost of £86,000. An Act of Parliament was obtained in April 1813, to authorise an canal with 23 locks suitable for 30-ton barges. All of the main structures, including aqueducts, bridges, locks and lock-keepers' cottages were designed by Jessop, and construction was managed by May Upton, the resident engineer. The Wey and Arun Canal project was completed in September 1816, having cost £103,000. In 1813 he surveyed and planned the Western Branch of the Montgomeryshire Canal. The canal had been opened to Garthmyl in 1797, but had not progressed any further because of a lack of finance. The existing section became known as the Eastern Branch, and Jessop surveyed a extension with 6 locks, which ran from Garthmyl to Newtown. His plans were accepted in July 1814, but there were delays in obtaining an Act of Parliament, as a result of opposition to the plans.