 He reported that if the locks and cuts were kept in good order and the millers prevented from lowering the water level that the navigation could be more successful and more reliable.Henshall and Thomas Dadford, Jr. (another pupil of James Brindley) surveyed the line of the Monmouthshire & Brecon Canal for a tramroad from Llan-march Coal and Mine Works to the Clydach ironworks.Henshall also worked for William Jessop while he was advising on the line of the Grand Western Canal.