The main aim of the archaeological buildings recording project was to create an accurate written and drawn record of the conserved structure of Brill windmill. The project was commissioned by Buckinghamshire County Council who have received funding assistance from GrantScape (www.grantscape.org.uk).
A photographic and measured survey of the structure and machinery of the mill was undertaken by Luke Bonwick and Martin Watts between May and July 2006. During this period, a series of sample cores were extracted from the principal timbers for dendrochronological analysis by Dr Martin Bridge of Oxford Dendrochronology Laboratory.
The results of the recording project were used to identify and assess the condition of each component in order to predict the level of repair needed for each item. Once the condition survey is complete, it was possible for Richard Oxley of Oxley Conservation to produce a conservation plan and repair specification, ultimately leading to the conservation and restoration of the structure and working parts.
BRILL MILL IN CONTEXT
There may have once been as many as 10,000 windmills in Britain. The post mill is likely to have remained the most favoured design of windmill for many years following its introduction, probably shortly prior to 1180 AD. Although the last ‘commercial’ post mill was built in East Anglia in the 1880’s, by this date windmills of all types were disappearing rapidly. By 1950, there were fewer than 100 post mills left standing in the country. The total today is 45, and this number includes a handful of examples which have been completely dismantled and rebuilt.
Although many post mills stand on ancient sites, fewer than ten can claim to have been constructed before the eighteenth century. Brill windmill in Buckinghamshire is one of only six remaining post mills proven, by dendrochronological analysis, to contain seventeenth century timbers. The others are: Pitstone mill, Buckinghamshire; Madingley mill, Cambridgeshire; Cromer mill, Herts; Drinkstone mill, Suffolk and Nutley mill, Sussex.
THE RESULTS OF THE TREE-RING SURVEY
The historical record, viewed in conjunction with the truncated inscription “–68–“, prominently on view inside the mill, have long been assumed to place the construction of the mill in the late 17th century. Dendrochronology has shown that the meal beam, at the front of the mill body, was made from a tree felled in the winter of 1685/6 – a date which accords well with the truncated inscription. This single date represents the first phase of construction identified.
The left and right side girts, together with the crowntree, appear to form a single group of timbers which were most likely felled during the period 1719 to 1733. These represent the second phase of construction identified.
The main post, a rear frame member and the right sheer all appear to come from trees cut later, possibly relating to a documentary reference from 1757: “Nov 2. Expenses of rebuilding a windmill which was blown down at Brill exclusive of value of old materials…” The substantial oak windshaft is of similar age, but as this retained complete sapwood it was possible to ascribe it a more precise felling date – the winter of 1759/60. These timbers represent a third, and possibly a fourth, phase of construction.
Samples taken from the eastern quarterbar and the north-south crosstree failed to provide positive dates.