Back on the Oxford!!! We So enjoyed the river.
Just before we go on, we thought it wise to explain why rivers have locks. Forgive us if you already know this, but for those who don't we try to be helpful (!). To be navigable, a body of water has to be deep enough to take a certain depth of boat (not that you'd know this by some sections of the canal network). Upstream of rivers is usually shallow, so there has to be some way to make rivers deeper to be able to continue to be navigable as much as possible. The cunning plan ages ago, was to dam rivers at intervals, allowing water to build up and therefore allow navigation further and further upstream. These dams are not permanent, but are lock chambers, allowing boats to go up the height of the dammed water, or to travel down from the dammed water to the lower level. A further cunning plan was as a result of angry farmers and mill owners who needed flowing water for their agriculture or for their mills. Allow some water to keep flowing around the dam/lock chamber so that the mill wheel still turns or so that water can still flow into irrigation chambers. This is what the weir is all about; the river still flowing whilst it still builds up in depth. Good, eh?
Canal locks on the other hand, are to allow water to go up and down hill; forget up and down stream. Just up hills, down hills, through mountains, over roads. Canals are water roads. Rivers are rivers. There. Said.
Anyway, we're back on the canal.
