Waterways

There is evidence that the Romans used rivers to transport goods and materials over long distances and the native tribes were building coracles (a hide covered frame) and other small craft before the occupation both for fishing and for transport.

The depth of a river varies according to the amount of water entering it along its course, thus in the season of rain and snow there will be a greater depth than in the dry season. In order to provide a sufficient depth of water weirs are built across the river to hold back the water.

In order for boats to be able to pass through the weir a device known as a lock needs to be incorporated. Originally these were a set of gates or paddles that the lock keeper opened which allowed water to pour through and the boat to follow. This type is known as a flash-lock. Its primary disadvantage is that far more water is allowed to escape than is necessary.

A later development was known as a pound lock. This type is a chamber big enough to hold the largest craft on the river with gates at each end to allow boats to enter and leave. The water level in the lock is controlled by opening and closing paddles at each end.

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