A water wheel had two general designs&colon; the undershot and the overshot. Bollington watermill, constructed in the 1860s, has an undershot waterwheel. In showing, a scissors bite is preferred with an undershot jaw severely penalised. All the machines were powered by Sorocold's 7 metres diameter, 2-metre wide external undershot waterwheel. The muzzle is short and generally wrinkle-free, with an even or a slightly undershot bite. Avro Anson DJ242 of 24 OTU undershot landing. It has a laterally flattened and high-backed body and a slightly undershot mouth. They were undershot mills with no mill ponds. A shaft ran to an undershot wheel in the dam raceway. Alongside it, another tide mill was found which was powered by a vertical undershot wheel. Undershot, overshot, or missing teeth are major faults. Undershot and stream wheel use large flows at little or no head. It is similar to the undershot water wheel mentioned later in this article. The basic construction is, of necessity, similar to an undershot water wheel. The efficiency of the mill can at best match a standard undershot mill.