The aisled wheelhouse at Middlequarter, Sollas, North Uist was inserted into a sand dune. It may have been partially roofed over, with an opening above the hearth. The door could be sealed by a draw-bar. There were cupboards in the house walls. The structure is unusual in having an additional side chamber on the north-east. (R.J.C.Atkinson)
One final group of buildings remains to be described, found mainly in the Outer Hebrides and, to a lesser extent, in the Northern Isles. Known as wheelhouses, these structures are usually circular and are divided up into compartments by internal stone walls arranged like the spokes of a wheel, with an open central area, often occupied by a stone hearth. In some examples, known as aisled wheelhouses the radial walls are separated from the house wall by a narrow gap.
Wheelhouses can be free-standing structures but more often they are sunk into a sand dune, the inner wall acting as a revetment against unstable sand. The radial walls must have helped support the roof which may well have been strengthened with rafters of whale bone, there being no local wood.
At Middlequarter, Sollas on North Uist the refuse from the house was piled in a midden over its roof, creating a virtually subterranean structure, entered from a long, funnel-shaped passage. The central room, about 9 m. (9.8 yd) in diameter, was divided into 12 bays, each wide enough to sleep two or three persons, or to act as store rooms. On one side a door led into an extramural oval chamber. Beside the central hearth, a stone-lined pit was used for storing water or shellfish. A stone quern indicated that grain had been grown and ground. The most bizarre feature of the Sollas wheelhouse was the discovery of some 200 sheep buried beneath the floor, mostly head downwards in small, conical pits. On the island of South Uist at the wheelhouse of A Cheardach Bheag some 20 deer jawbones had been set in an arc around the central hearth, and at the neighbouring site of A Cheardach Mhor 32 ox teeth were found beside one of the piers.
Wheelhouses usually occur close to fertile machair land and are not defended in any way. They seem to have been the Iron Age equivalent of the modern island croft. There is no clear dating for the beginning of wheelhouses although there are good reasons for thinking that they follow the demise of the brochs, their open, unprotected sites perhaps indicating less troublesome times. They seem to have flourished in the later Scottish Iron Age of the second to fifth centuries AD.