However, an Act was obtained in 1815, and Jessop oversaw the project between then and 1819, when construction was completed. John Williams was the engineer on site, and the project cost £53,390. Although the construction work was completed in March 1819, it was not reported to be finished until December 1821. In 1805, Benjamin Outram, the owner of the Butterley Company, died, and the Jessop family moved from Newark to Butterley Hall, so that William Jessop, the younger brother of Josias, could take over as manager of the company. Since 1794 they had manufactured cast iron plate rails for tramways, but in 1813, experimented with I-section edge rails, and Josias used these rails on his next project, an railway which ran from Mansfield to the Cromford Canal at Pinxton. Construction of the Mansfield and Pinxton Railway was authorised on 16 June 1817, and an opening ceremony was held on 13 April 1819, close to a viaduct which carried the railway over the River Maun at Mansfield. A local newspaper report described it as "the beautiful five-arch bridge, constructed under the direction of Mr. Jessop, the engineer." It was adapted for locomotive traffic in 1847, and is now used as a footpath. It was restored in 1990, and is a grade II listed structure. Jessop was also consulted on harbour works, recommending an extension to the east pier at Newhaven harbour in 1819, which was completed the following year, while is 1823 and 1826 he reported on Plymouth Breakwater, in the first instance jointly with Thomas Telford, George Rennie and John Rennie, and in the second with William Chapman and John Rennie. His final project was the Cromford and High Peak Railway, which crossed the Pennines to link the Cromford Canal to the Peak Forest Canal. He surveyed the route in 1824, and proposed a line, which would use a series of steep inclines powered by stationary steam engines to raise the level by on the Cromford side, and drop it by to reach Whaley Bridge. An Act was obtained in May 1825 and construction began, with Thomas Woodhouse as the resident engineer. Woodhouse saw the project through to completion in 1831, after Jessop's death in 1826. The summit tunnel includes a stone inscribed 'Josias Jessop Engineer'. Some idea of the stature of Jessop as an engineer can be gained from events concerning the proposed Liverpool and Manchester Railway. The original