Unpublished manuscript, 'On the conditions for effective scour in drain pipes of circular section' by H [Henry] Hennessy Hennessy writes on effectively clearing drain and sewer pipes which are liable to deposits, illustrated by a mathematical example. Annotations in pencil and ink throughout. Includes a diagram of a cross-section of a drain pipe. Subject: Hydraulics / Mathematics Received 1 March 1889. Read 28 March 1889. Mentioned as received in volume 45 of the Proceedings of the Royal Society as 'On the conditions for effective scour in drain-pipes of circular section'. 1889