How does a canal lock system work?

[rustynail]

How does the lock system on a canal work? For example, restoring water levels once a vessel has passed from one lock to another.

[buildersmate]

The water either comes from a natural river system fed into the canal system at the highest point of the route (and sometimes at mid-points as well), or it is pumped up. The Victorian engineers were quite ingenious at devising ways of maintaining the water supply and there are various examples of pumping engines and windmills still dotted around the countryside. Many a canal scheme failed due to its inability/miscalculation to supply adequate water.

[SteveD]

Here is a little animation:

http://www.starling101.btinternet.co.uk/canals /lckworks.htm#