Eling Tide Mill

How the mill works

How the water drives the mill

When the flooding tide comes in it pushes open one-way gates (the ‘sea gates’ or ‘sea hatches’) at the other end of the dam from the mill and fills up the 3km stretch of the river upstream of the mill which we call our mill pond. The mill cannot work at this point for two reasons: first the water levels are equal so there is no flow of water and secondly the waterwheel is largely underwater itself so is unable to turn because of too much drag.

When the tide starts to go out again (the ebbing tide) the water level on the seawards side drops, gradually uncovering the waterwheel. At the same time the sea gates close trapping the water in the mill pond. This trapped water is now ready to be used as the fuel for turning our machinery.

Once the tide has dropped enough to reveal at least half of the waterwheel we are able to begin milling. By opening the sluice gate we release water which starts to turnthe machinery. While the machinery is turning it is not at its most efficient because there is still a lot of ‘drag’ on the waterwheel. As the tide continues to drop more and more of the waterwheel is uncovered. It reaches maximum efficiency when the tidal water is no longer touching any of the paddle blades on the waterwheel.

How the mill works

As the waterwheel revolves the pit wheel, sharing the same axle, revolves at the same rate. There are 108 bevelled teeth on the rim of the pit wheel which mesh with 50 on the wallower, converting the relatively slow vertical movement to a faster horizontal rotation. The wallower turns the main vertical shaft on which are mounted the great spur wheel and the crown wheel. 107 teeth on the spur wheel drive two stone nuts, or smaller wheels, that turn the grinding stones. These have only 23 teeth each so increase the speed of rotation still further. The number of teeth (cogs) is deliberately irregular to ensure that the same teeth do not mesh together every rotation.

The spur wheel and stone nut are made of cast iron, but the spur wheel has wooden teeth which are typically made of hornbeam, apple, oak or beech. Such teeth form the weak link in the system, like an electric fuse, designed to break in an emergency when something has to give. They are relatively easy to replace if damaged or broken. Spare teeth would often have been made during times when the mill was unable to work such as high tides. Wood on wood is considerably quieter that metal on metal but wood meshing with metal teeth is thought to give the smoothest running.

The grinding face of each millstone is cut with a radiating pattern of grooves. This is done in such a way that when one stone is laid upon the other, the grooves or furrows cross each other at an angle. Special tools are needed to dress the stones – a mill bill to chip out the pattern and a proving staff to check that the surface has no high spots.

Grain enters the stones at the centre and slowly moves outwards through the scissoring motion of the rotating of the runner stone. Initially the grain is broken open but the further from the centre the grain gets the finer it is ground down until it is turned into flour. On the outside of the stones there is a pair of sweeps that push the flour towards the flour chute and into the waiting sack below. It is then measured out for sale to the public.