An article from the Dover Express is perhaps a good summary and sets the scene:
Leading archaeologists were called to one of Dover's busiest tourist attractions after an exciting discovery was made beneath its floor. Volunteers at Crabble Corn Mill in Lower Road had been digging in the building to instal equipment allowing the site to run of power from water in the River Dour. But as they went deeper into the wheel pit they found something unexpected underneath - an ancient wooden floor. Neil Anthony, founder of the Crabble Corn Mill Trust, said "it's very, very exciting. Whatever it is, it predates our mill by centuries."
The plans are to scale in their original format, but not as displayed above. Here, they are for illustrative purposes only, courtesy of Howard Austin Jones, as are the accompanying notes, and are copyright to him.
Notes on the Building Phases at Crabble Corn Mill
pre eighteenth century
The Domesday Book of 1086 records four mills along the river Dour in Ewell: the location of these is not known. It is quite possible that there were watermills here in Roman times, and evidently they continued to exist through the medieval period.
mid eighteenth century
The earliest surviving part of a watermill would appear to be the wheel pit excavated in the autumn of 2007. It comprises a brick lined pit approximately six metres long east-west by two wide (i.e. twenty feet by six foot six inches wide), set at right angles to the southerly flow of the river. The pit is open at its east end, the flanking walls were originally braced by a brick arch between. Its base is approximately two metres below water level at that point. The base comprises a lattice of timbers (probably oak) at 900mm (3 feet) centres across the pit, and 560mm (22 inch) centres along it. The lattice is inclined to provide a close fit with the base of the water wheel, and the timbers are tenoned and pegged together with a brickwork infill between them. Timber planks between 100-200mm (4'-6') wide and 50mm (2") thick are nailed over, lying along the direction of the flow of water. These planks have been replaced two or three times in the lifetime of the wheel, and those which survive are worn to half their original thickness. No evidence of the support to the waterwheel survives, but the angle of the base of the pit and scars on its walls suggest it had a diametre of 4.25 metres (14'6"), and that the water to drive it came in at a level about halfway up. It is not clear why the wheel was set at right angles to the flow of the river, rather than along it: perhaps this allowed greater control of the flow of water.
The water on leaving the pit was taken away by means of a leat, 2m (6'6") wide with low sides of brick work (later extended upwards to form a deeper channel) and a base of timber planks nailed onto transverse beams 900mm (3') centres. These planks appear not to have been replaced, and the leat continues for a distance of some 11m (36').
The nature of these timbers and the brickwork are consistent with a date in the mid eighteenth century, and the replacement and wear on the timber and bricks suggest it was in use for perhaps 20-30 years.
The location of the building housing the mill equipment at this time is not certain, but most probably it was on the site of the present mill.
mid/late eighteenth century
Shortly after the wheel pit was finished, and while it was still in use, a two-storey brick building 11.5x13m (37'x43') with timber sash windows and most probably, a low-pitched slated roof, was constructed to the south of the pit and over the leat. The inside of this building contained a grid of oak posts and beams to support the first floor, and those to the northern half of the building would appear to be of this time.
early nineteenth century
A major rebuilding too place c.1812, when the corner of the two storey building was demolished to accommodate the present six-storey mill tower. The bottom half was walls of brickwork, the upper of timber frame clad in weatherboarding. Both contain timber sash windows, and the low-pitched roof slated. The floors within this tower are supported by a grid of oak posts and beams.
The water wheel driving the equipment was positioned to the west of the tower, in line with the flow of the river and where its later replacement still is. The existing wheel was removed and the leat covered over by a single storey extension. It was at this time that the walls to the leat were extended upwards, to meet the new floor.
later nineteenth century
In c.1874, the water wheel and its associated equipment were replaced with that which presently survives. A first new floor was built over the single storey extension to the north.
