Details

The monument includes Sibsey Trader Windmill, a six-sailed tower mill built in
1877 by Saunderson & Son of Louth. Originally there were four pairs of
millstones; in the early 20th century a further pair was installed, run by an
engine housed in an exterior engine-shed. The mill was in regular use until
1953, after which date the engine was removed and the mill fell into
disrepair. In 1975 the mill passed into the care of the Secretary of State and
was subsequently restored to working order. The monument includes the mill, a
Grade I Listed building, complete with gear, sails and other fittings; it also
includes the base of the engine-shed and buried remains associated with an
earlier post mill which the tower mill was built to replace.

Sibsey Trader Windmill is located on the edge of the West Fen about 1km west
of Sibsey parish church. It takes the form of a tarred brick tower of six
storeys tapering upwards to the curb, a circular cast-iron track on which the
cap is rotated. At third-storey level is an exterior gallery with ornate
wrought-iron railings. The cap is ogee-shaped and is weatherboarded. Fixed to
the cap are six wooden double-sided sails of Cubitt's Patent type, the speed
of which is regulated by double sets of movable shutters. The shutters are
controlled by a series of rods which are connected to the striking gear on the
opposite side of the cap; the striking chain and weight are suspended to
gallery level where they can be adjusted. Also on the cap is a wooden fantail,
the movement of which rotates the cap to turn the sails into the wind. The
tower and cap together reach a height of approximately 22.6m.

On the interior of the mill are six storeys with whitewashed walls, timber
floors and interconnecting ladders. Running through all six storeys is the
central upright shaft, turned by the sails, and the sack hoist chain, by which
sacks of grain are carried from the ground floor to the upper storeys through
a series of trap doors. The ground floor is reached by a short flight of
brick and stone-flagged steps. It is now occupied by a wooden elevator dating
from the first half of the 20th century when a pair of engine-driven
millstones were installed here, since removed. Also on the ground floor is
part of a sail, recently fitted for display purposes. Originally the ground
floor was an open area used for bagging flour fed down wooden chutes from the
millstones above, and for fixing sacks of grain to the sack-hoist to be
carried to the grain bins in the upper part of the tower. Beneath the ground
floor is a low basement, reached by a trap door, which was used for the
storage of empty sacks. Above the ground floor is the meal floor. On this
storey are the governor and tentering gear, which control the gap between the
millstones on the floor above, and the tensioners which control the flow of
grain onto the millstones. Also on the meal floor is a millstone, recently
fixed for display purposes. Above is the stone floor where the millstones are
located. Three of the original four pairs of millstones survive, fitted in the
original wooden vats. One pair of stones is still in use and the vat is now
lined with aluminium. Above the vats are wooden hoppers from which the grain
is fed onto the millstones. Each of the upper `runner' stones is fixed to a
quant, a vertical shaft which terminates in a small horizontal iron wheel
known as the stone nut. In turn, the stone nuts are engaged to the great spur
wheel, a large horizontal iron wheel beneath the ceiling, which is turned by
the upright shaft. On the stone floor are two opposing wooden doors giving
access to the gallery. Above the stone floor are two bin floors where the
grain bins were located; part of a wooden bin survives on the upper floor. In
the floors are small holes, now covered with perspex, through which the
sacking spouts ran to the stones below. On the top storey is the dust floor,
open to the cap, where an iron wind shaft runs between the sails and a
vertical brake wheel and brake; the brake is connected to a horizontal wooden
lever by which the brake wheel is released to allow the wind shaft, and thus
the sails, to turn. The brake wheel is engaged with a horizontal iron wheel,
the wallower, on the upright shaft. Adjacent to the upright shaft is the sack
hoist gear, also run by the wallower. Here the curb may be seen resting on top
of the brick wall; running down the inside of the wall is a series of iron
holding bolts which keep the curb in place.
Adjacent to the north west side of the tower is the base of a rectangular
building approximately 8.5m long and 3.5m wide. The floor is constructed of
concrete. This represents the remains of an engine-shed built to house an
auxiliary oil engine in the early 20th century. In the north wall of the
tower is a small aperture, now sealed, through which the engine was connected
to the pair of millstones which formerly occupied the ground floor.

Adjacent to the west of the tower is a raised area of accumulated deposits,
over 5m in diameter and about 0.3m high, sloping down slightly to the base of
the engine-shed on the north, the track on the south and the fence on the
west. The archaeological deposits in this area are considered to represent
buried remains associated with the post mill which occupied the site prior to
the tower mill.

The millstone on the meal floor and part of a sail on the ground floor, which
are fitted for display purposes are not included in the scheduling. The two
millstones which are now leaning against the exterior of the tower and the
parts of the original curb which lie near the east side of the tower, are not
included in the scheduling although the ground beneath them is included.

MAP EXTRACT
The site of the monument is shown on the attached map extract.
It includes a 1 metre boundary around the archaeological features,
considered to be essential for the monument's support and preservation.

Source: Historic England

Reasons for Scheduling

A tower mill is a type of windmill in use during the late medieval and post-
medieval periods, which owes its name to the housing of the milling gear in a
tapering tower of brick, stone or wood. The sails are fixed to a rotating
timber-framed cap. On early tower mills the cap was rotated manually to move
the sails in and out of the wind, while on later examples, which were
generally taller and carried a greater number of sails, it was moved
automatically by means of a fantail. Towers built of stone or brick were
usually circular in plan and their sides were protected from the weather by
paint, tar or tiles; timber-framed towers, known as smock mills, were built
onto a brick base and were normally octagonal in plan and protected by
weather-boarding. Used primarily for grinding grain, tower mills had a wide
distribution but were most common in the grain growing areas of south and east
England where there was insufficient water power to run an adequate number of
watermills. In some areas tower mills were also used to pump water or to saw
wood. There were about 10,000 tower mills in England at the peak of their
construction in the mid-18th century; they declined in use in the late 19th
century due to increased use of steam power, although some continued to
function into the 20th century. Formerly a common feature of the English
landscape, less than 400 tower mills are known to survive, principally of the
mid-18th to mid-19th century. Tower mills preserve valuable evidence for the
development of milling technology and the economy from the late medieval
period to the 20th century, and many have acquired an important amenity and
educational value. All examples surviving in good condition, particularly
those which contain their machinery intact, demonstrate unusual
characteristics or significant associations, are considered to be of national
importance.

Sibsey Trader Windmill is a rare example of a complete tower mill which has
been restored to working order. As a multi-sailed windmill with an
ogee-shaped cap it is characteristic of a particular region, and is one of
very few six-sailed windmills still surviving. Built in 1877 it is an
unusually late example of this type of monument in a part of the country where
windpower continued to be exploited for a longer period than in more
industrialised areas; it is therefore representative of its local historic and
economic environment. With the buried remains of an earlier post mill and the
site of the later engine house, the monument preserves evidence for the
evolution of milling on the site which will tell us how this activity
originated here and developed into its present form. As a monument in the
guardianship of the Secretary of State, Sibsey Trader Windmill serves as an
important educational and recreational resource.

Source: Historic England

Sources

Books and journals
Brann, M, The Engine Shed, Sibsey Trader Windmill, (1993)
Dolman, P, Lincolnshire Windmills: a contemporary survey, (1986), 25
Other
Apted, M R, Sibsey Trader Mill, 1986, pamphlet
Title: Boston
Source Date: 1824
Author:
Publisher:
Surveyor:
1 inch map

Source: Historic England