Before revision: Basic construction and operation upright=1.5|A plan and side view of a generic, empty canal lock.
After revision: In Ancient Egypt, the river-locks was probably part of the Canal of the Pharaohs: Ptolemy II is credited by some for being the first to solve the problem of keeping the Nile free of salt water when his engineers invented the lock around 274/273 BC.Gmirkin, Russell Berossus and Genesis, Manetho and Exodus: Hellenistic Histories and the Date of the Pentateuch T.T.Clark Ltd (24 Aug 2006) p.236Basic construction and operation upright=1.5|A plan and side view of a generic, empty canal lock.