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Local needs
Land owners in the upper Thames used to control local stretches of the river to ensure that there was a sufficient water supply for their water mills. The dams and weirs created became ideal points to set fish traps.
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Fish traps |
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Carrying over at a weir |
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Tension
Damming the river created tension with those navigating up and down stream. Goods and passengers had to be unloaded, and the boats and barges had to be dragged around the obstacles. Fights often broke out, and barges moving downstream sometimes simply smashed through older rotting structures.
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Early locks
Early removable flash locks consisted of vertical paddles which could be removed from a wooden frame that could then be swung aside. Boats moving downstream could then be carried by the water. Boats heading upstream, would have a rope attached, and be winched up through the rushing water, until the paddles could be replaced, and the water calmed once more.
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Flash lock |
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Opening a lock |
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So much water could be lost when a lock was opened that it might take two or three days before the water depth was sufficient for local needs again. The balance between local requirements and the need to transport goods up and down the river Thames have been controlled by royal edict since medieval times, and later acts of Parliament.
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Victorian Engineering
We can thank the Victorians for the modern structure of locks. One of the best examples is the complex but beautiful structure of the Richmond Lock and Weir. It has a massive lock, which at its opening in 1894, was said to take six barges and a tug, as well as rollers for dragging boats, which reduced costs and the loss of water in times of drought.
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Richmond lock and weir |
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