Observation and various historical records
General description of Michaelchurch Mill
Michaelchurch Mill is powered by an overshot iron wheel, twelve feet in diameter and three feet six inches wide. It has thirty six buckets, and the driving force is generated by the weight of the water retained by these buckets as it enters the top of the wheel and then falls under gravity to be discharged at the bottom as the wheel turns. This particular wheel will develop about twelve horsepower, sufficient to drive the two pairs of four-foot diameter millstones and the other ancillary equipment in the mill.
There is structural evidence that a rather smaller wheel was in place at one time, which most likely would have been made of oak. The current wheel was probably installed in the early1800’s (a survey of the Michaelchurch Estate c 1830 refers to extensive refurbishment of the mill), along with the other cast iron drive cogs, when the technology for making large-scale iron castings had become widely established. Such a waterwheel would have cost around £340 in 1860, the equivalent of many thousands of pounds today.
The water to drive the mill is extracted from the Escley Brook at a weir about 400 yards upstream. There a sluice gate controls the flow into the leat which brings the water to the rear of the mill. Two intermediate drains automatically regulate the water level by discharging any excess back into the brook.
As with any watermill, the flow of water was a critical factor. It is estimated that under working load a constant supply in excess of 200,000 gallons per hour would have been needed to drive the machinery here. To compensate for rises and falls in the river level, in times past the leat fed a mill pool (filled in during the building conversion in the 1980’s) which provided a working reserve at times of low water in the Brook, and allowed the Miller a degree of independent control.
However, shortage of water seems to have been a constant problem at Michaelchurch. To counteract this, the mill leat was linked at one time to a supplementary reservoir providing a separate water supply from the adjacent hillside to the West of the mill. There is no record of when the earth dam and the sluice were constructed. They fell into disuse probably sometime around the end of the nineteenth century (nobody surviving today has any recollection of this arrangement being used), but their remains can still be seen clearly. Now a sluice gate controls the flow of water to the wheel through an underground pipe directly from the head race.
Once the water has passed over the wheel it escapes through the tail race. This is a large stone culvert which goes under the Vowchurch road to emerge just downstream of the bridge.