[EMAIL PROTECTED] wrote: > Did the flight ever have any? I thought the whole of Rochdale was built > without them.
As I understand it, that's correct. The hirers' notes that a local boat hire company used to put in their boats included a Q&A section explained the overflow arrangements and contained something memorable along the following lines... Q: But that's not a very clever way to design a lock, is it? A: The system was devised by William Jessop, the finest engineer who has ever graced our waterways, or ever will. Splended though this rejoinder is, I feel that it doesn't move us very far forward in terms of whether or how we should adapt good 18th century working designs to be more suited to modern pleasure boat use... But it does tend to support my belief that the Rochdale locks originally (ie in the case of the ones on the trans-Pennine length, until the 1990s) lacked conventional bywashes, instead relying on the system involving slots in the upper gate recess walls. These allow water to overflow into the chamber via the upper ground paddle culverts (possibly supplemented by water coming over the top gates when there is too much for the slots - which are relatively short compared to conventional bywash weirs - to cope with), and bottom gates which are (or should be) designed with the tops of the gates at exactly the same level as these slots, so that if the lock is full the water will overflow over the bottom gates. The same system was used elsewhere (GU, K&A, Basingstoke that I know of) and does seem to have been favoured by Jessop. Martin L
