GRAIN CAN BE GROUND between two parallel circular stones, one of which was rotating. The grain was fed between the stones which broke it up to form flour. The rotation was usually powered by harnessing either the energy of wind (as in windmills) or of flowing water (as in watermills).

Many watermills are powered by water flowing in streams or rivers. At Woodbridge in Suffolk, a different system is employed. At high tide, the sea water enters a pond next to the water mill via a channel fitted with a one-way valve that allows water to enter the pond but not to leave it. The water that has accumulated in the pond can be released from it by a valve that allows the water to escape via a mill wheel fitted with paddles, rather like the paddle wheels on old-fashioned paddle steamers. The water flowing out of the pond causes the wheel to rotate. This rotation is transmitted to the grain grinding stones via a series of cogwheels. The mill at Woodbridge is an example of what is known as a ‘tide mill’.

There has been a mill on the site of the Woodbridge tide mill since the 12^th century. There was some kind of tide mill on the spot since at least 1340. The present tide mill buildings have been standing since at least the beginning of the 19^th century. It might well be the mill that was rebuilt in the 17^th century.

Today, the tide mill is open to the public. It is still in working condition and used to produce flour. Visitors, including us, are shown the mill in action, subject to there being sufficient water stored in the pond. We were fortunate to see this remarkable piece of engineering in action.