Blowing House And Attached Walls At Approximately 10 Metres North East Of Blowing House Cottage

Blowing house and attached walls at approximately 10 metres north east of Blowing House Cottage

This is a blowing house (a building where tin was smelted with a forced draught) with attached remains of a second ruinous blowing house. Dating from the 16th and 17th centuries with some 19th-century alterations, these are the key surviving structures of the Godolphin family tin works.

The earlier walls are constructed of coursed granite rubble, with the later sections of random rubble. Granite lintels are used throughout, including a finely dressed example in the north gable end above which sits an early 19th-century brick stack. The roof is scantle slate with gable ends.

To the north are adjoining walls 1 to 2 metres high of another building, open to the east. The earlier and larger building to the north is rectangular in plan and roofless. Its north gable end contains an upright hearth and locker arrangement similar to those found on Dartmoor blowing houses. This gable was subsumed by a later, smaller blowing house built onto it to the north, which is also rectangular. Its doorway is at the south end of the east wall, which appears to date from the late 18th or early 19th century and reuses several inscribed (bound) stones. The back wall aligns with the corresponding wall of the earlier blowing house, meaning the leat (existing in part) needed only a short extension.

The north gable end is of exceptional interest. On the outside, a large granite lintel has its lower edge shaped to a double undulation to receive the barrels of two bellows. The opening below is splayed with a granite sill. The inner opening is very small and retains a piece of iron grill. Two bellows would have stood in a frame outside and immediately north of the building, operated by a small water wheel via a cam shaft and counterweights. Within the building, a temporary furnace known as the 'castle' was built where black tin (powdered ore) was melted by charcoal fire, raised to temperature by the alternating mechanical bellows.

These structures are part of the broader Godolphin tin works site, which includes remains of stamps, leat systems, buddles and other equipment. According to the Survey of Cornwall by Richard Carew, Sir Francis Godolphin (1534–1608) innovated tin production processes, including blowing, with assistance from a German mineral expert. Two blowing houses survive here: the earlier with a Dartmoor-type hearth, and the later, built onto it, with a more sophisticated hearth similar to those illustrated in De Re Metalica. The second is likely substantially Sir Francis's blowing house, and together the two structures illustrate his profitable improvements to the process.

No other substantial remains of blowing houses are known to survive in Cornwall, and none of the Dartmoor examples is as complete. This is a building of considerable value to industrial archaeology.