Reasons for Designation
The Isles of Scilly, the westernmost of the granite masses of south west
England, contain a remarkable abundance and variety of archaeological remains
from over 4000 years of human activity. The remote physical setting of the
islands, over 40km beyond the mainland in the approaches to the English
Channel, has lent a distinctive character to those remains, producing many
unusual features important for our broader understanding of the social
development of early communities.
Throughout the human occupation there has been a gradual submergence of the
islands' land area, providing a stimulus to change in the environment and its
exploitation. This process has produced evidence for responses to such change
against an independent time-scale, promoting integrated studies of
archaeological, environmental and linguistic aspects of the islands'
settlement.
The islands' archaeological remains demonstrate clearly the gradually
expanding size and range of contacts of their communities. By the post-
medieval period (from AD 1540), the islands occupied a nationally strategic
location, resulting in an important concentration of defensive works
reflecting the development of fortification methods and technology from the
mid 16th to the 20th centuries. An important and unusual range of post-
medieval monuments also reflects the islands' position as a formidable hazard
for the nation's shipping in the western approaches.
The exceptional preservation of the archaeological remains on the islands has
long been recognised, producing an unusually full and detailed body of
documentation, including several recent surveys.
The animal driven mill, using draught animals walking a circular track and
harnessed to an arm which turned a rotating structure, has been known since
the Classical Roman period, but until the early post medieval period (from AD
1540) it received only limited application for grinding and crushing purposes
at the relatively small numbers of sites, such as monastic or manorial
establishments, which handled agricultural produce in sufficient quantities to
make it worthwhile. From the mid-16th century, simple animal driven grinding
and crushing mills became widespread in farmyards; in the mining industries
they were developed to form the horse engine, often called the `horse whim',
where the turning motion generated by the animals was transmitted by shafting,
ropes and simple gearing to power ore hoists and water pumps. The more
sophisticated horse engine only appeared in farming contexts in the late-18th
century technological revolution which gave a rapid rise in agricultural
output and which both reflected and caused a shift of labour from the land. It
was the invention of threshing machines to replace hand-flailing that from the
1770s made the horse engine a necessary part of many farmyards.
The crushing mill 270m south west of Blockhouse Cottage, Tresco, survives well
as a good and early example of the simple form of animal mill despite the
absence of its original pivot post, cross bar and edge-runner, a loss which it
shares in common with the few such pre-19th century animal mills that survive.
It has one of the largest known base stones of any surviving animal-driven
mills of this type and is unusual in being carved directly from the bedrock.
It is also unusual in being securely datable to the 18th century or earlier by
virtue of its method of manufacture and its initial historical record.
Details
The scheduling includes an 18th century or earlier animal-driven crushing mill
on the plateau of Middle Down on central Tresco in the Isles of Scilly.
By local tradition and analogy with comparable examples elsewhere this mill
served as an apple crusher to provide pulp for making cider. It survives with
its combined pivot and crusher stone intact where it was recorded by the
antiquary Troutbeck in 1796. The stone is circular, carved directly from a
large bedrock exposure, and measures 2.8m in overall diameter, rising up to
0.4m above the surrounding ground level. It has a raised inner platform, 1.3m
in diameter, concentric around a central socket, 0.2m diameter and 0.23m deep,
which accommodated the mill's former pivot post. Beyond the inner platform is
a broad flat-bottomed channel, 0.5m wide and 0.3m deep, along which an
edge-runner slab turned. Beyond the channel, the stone's raised outer rim is
approximately 0.3m wide; its uneven roughly worked surface is slightly lower
on the north west side and it bears a small rectangular slot carved on its
south east sector. The outer face of the stone bears numerous shallow facets
that are the typical result of splitting using wedges, the dominant method of
stone-splitting prior to AD 1800. Beyond the outer rim the bedrock surface,
now overgrown, is levelled over a width of 1.1m concentric with the stone to
provide the track for the draught animals that drove the mill.
The mill's operation will have involved a cross bar secured to the central
pivot post; the cross bar formed the axle on which an edge-runner slab
revolved along the channel and it was driven by a draught animal, a horse, cow
or even donkey, harnessed to one or both outer ends of the cross bar and set
to walk a circular path outside the outer rim of the mill's base stone.
Although now overgrown, a late-19th century photograph of this base stone
shows the levelled track for the draught animals extending 1.1m beyond the
stone's outer rim and delimited on the east by a small rise in the bedrock
exposure.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
It includes a 2 metre boundary around the archaeological features,
considered to be essential for the monument's support and preservation.
