The father of Mr. Jessop was engaged under Smeaton in superintending the erection of the Eddystone Lighthouse, and his son William, the subject of this memoir, was born at Plymouth. When he had attained the age of sixteen his father died, leaving the guardianship of his family to Smeaton, who thenceforth adopted William as his pupil, determining to bring him up to his own profession. Young Jessop remained with Smeaton for a period of ten years, enjoying, during this the busiest part of Smeaton's active career, many opportunities of acquiring an extensive knowledge of the business of civil engineering. After leaving the service of Smeaton, Mr. Jessop was engaged for several years in improving the navigation of the rivers Aire and Calder, and of the Calder and Hebble in Yorkshire. He was also employed on the river Trent in Nottinghamshire, and he appears to have been principally occupied on these works for some time subsequent to his leaving Smeaton. A few years before the retirement of the latter, which took place in 1791, his pupil began to obtain active employment, and we find him about the years 1788 and 1789, reporting on the navigation of the Sussex Ouse, and the drainage of Laughton Level in the same country, being called on, at the same time, by the Commissioners of the Thames and Isis, to advise on the works they had undertaken, and were about to execute, for the improvement of this important navigation. In the three following years (1790-2) his professional employment greatly increased. He was now actively engaged in prosecuting various important canals in connection with the great central navigation of the Trent. Amongst these were the Cromford Canal, penetrating amongst the mountains of Derbyshire into the rich mineral districts of that wild and romantic country; the Nottingham Canal, which connects the Cromford with the Trent at Nottingham; the Loughborough and Leicester navigation, connecting the Ashby Coalfield with the navigable part of the Soar and with Nottingham, thus opening an important communication with the Trent on the one hand, and with Nottingham and the whole south of England on the other. In addition to this system in connection with the Trent, he projected and commenced at this time the Horncastle navigation, which, besides acting as a valuable drainage for this part of the fens, was productive of great benefit to a large district, by bringing it into communication with the river Witham, which is navigable to the sea in one direction, and in the other through Lincoln to the Trent.