Post-medieval animal-driven crushing mill 270m south west of Blockhouse Cottage, Tresco


Heritage Category:
Scheduled Monument
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Date first listed:


Ordnance survey map of Post-medieval animal-driven crushing mill 270m south west of Blockhouse Cottage, Tresco
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The building or site itself may lie within the boundary of more than one authority.

Isles of Scilly (Unitary Authority)
National Grid Reference:
SV 89466 15203

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.


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.


The contents of this record have been generated from a legacy data system.

Legacy System number:
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Books and journals
Arlott, J, Island Camera, (1983)
Grigson, G, The Scilly Isles, (1977)
Worth, R H, Worth's Dartmoor, (1981)
Tangye, M, 'Cornish Archaeology' in An Unusual Cider Press, Tresco, Isles of Scilly, , Vol. 7, (1968), 108
Gerrard, S., English Heritage Book of Dartmoor, 1997, Forthcoming
Gerrard, S., English Heritage Book of Dartmoor, 1997, Forthcoming
Parkes, C/CAU, AM 107 for Scilly SMR entry PRN 7372, (1988)
Title: 1:2500 Ordnance Survey Map; SV 8915 Source Date: 1980 Author: Publisher: Surveyor:


This monument is scheduled under the Ancient Monuments and Archaeological Areas Act 1979 as amended as it appears to the Secretary of State to be of national importance. This entry is a copy, the original is held by the Department for Digital, Culture, Media and Sport.

End of official listing

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