perry was succeeded by john grundy, sr., who published a paper in 1734 on flow in open drains. he calculated theoretic flow rates, and then used observation in the field to modify the results. he oversaw a programme of repairs to the deeping bank, which ran for along the north and west side of the river, while john scribo was employed to do the same for the country bank, which ran for on the south and east. grundy made the river deeper above spalding, and also constructed a sluice and reservoir at the mouth of the glen. the reservoir covered and provided water to scour the channel below the sluice. his son, john grundy, jr., took over after the death of his father in 1748, and spent nearly £10,000 on bank repairs between then and 1764. he rebuilt perry's sluice soon after 1750, with taller doors and a set of tide gates to prevent the tide moving upstream, and rebuilt the navigation lock in 1754. after 1764, thomas hogard became the surveyor of works, but grundy continued to act as a consultant engineer.