lock: wheel

a wheel to close the lock. A pipe adding water from another ditch (?)

 

For those of you unfamiliar with the 'lock phenomenon' (those living with too little or just enough water around!): a lock is an instrument to regulate water levels. In a system with canals and ditches, designed to keep low lands dry, the levels of one canal will get (too) high. In order to get rid of the surplus a lock is installed. In large canals used for transport a ship can use a lock to get from a lower to hiogher level canal or the other way around. I found you a good descrition of its workings here

Done