For the LORD thy God bringeth thee into a good land, a land of brooks of water, of fountains and depths, springing forth in valleys and hills; a land of wheat and barley, and vines and fig-trees and pomegranates; a land of olive-trees and honey; a land wherein thou shalt eat bread without scarceness, thou shalt not lack any thing in it; a land whose stones are iron, and out of whose hills thou mayest dig brass. - Tanakh, Deuteronomy (8, 7-9)
The wooden dam of Pede's Mill is used to retain the water upstream of the mill. Its height is determined by the relief of the land and by the flow rate and regularity of the brook (average flow rate, flow rate in periods of flood and flow rate in periods of low water). Here we see that the banks of the brook have been raised at the location of the mill, in order to give the dam sufficient height to operate the water wheel.
Overshot water wheel
We distinguish three types of water mills according to their feeding point, either at the upper part, middle part or lower part of the water wheel (overshot water wheel, breastshot wheel or undershot water wheel). Pede's Mill is of the first type.
To drive a mill with overshot water wheel, it is necessary to have a waterfall of 2.5 to 3 metres. An additional condition is the presence of a valley wall. As this part of the Zwalm valley is characterised by relatively gentle slopes, an artificial waterfall has been created and the course of the brook has been moved up partly against the valley. The original course of the brook has been abandoned and rearranged higher up the valley slope. Past the mill, the brook regains its original course.
The rearrangement of the brook's course and the necessary raising of the land are an important alteration of the countryside, not only at the location of the mill and the dam, but also upstream and downstream. Upstream (upper course or mill race), the higher water level can have an influence on a wide area, to an extent that pastures and arable lands situated at a higher location could be affected. In most cases, the competent authorities placed a depth gauge (fixed calibration point) alongside the dam, above which the water was not to rise. This calibration point normally consists of a metal insert in the abutment sidewall or wing wall (wall that consolidates the banks of the brook) just before the dam. No calibration gauge can be found at Pede's Mill today, but it is possible that there was one during the last centuries.
Also downstream (lower course or tail race), retaining water before a mill session can affect the water level of the brook and possibly the amount of available water for other mills downstream.
Barrage right is a property right granted to the miller, to allow him to retain the necessary amount of water. This right is rarely put down in writing in deeds, but it is established as land servitude through age-old, usually immemorial usage.
The next chapter at a glance:
Where we will have a closer look at the head race, which will transport the water over the water wheel.