Lever force F at a point "A" located by the coordinate vector r on the bar. The lever then exerts an output force F at the point "B" located by r. The rotation of the lever about the fulcrum "P" is defined by the rotation angle "θ" in radians. Let the coordinate vector of the point "P" that defines the fulcrum be r, and introduce the lengths which are the distances from the fulcrum to the input point "A" and to the output point "B", respectively. Now introduce the unit vectors e and e from the fulcrum to the point "A"
Darcy Lever constructed with a timber frame with plaster fill and a grey slate roof in the Tudor style. It was located on the high ground that slopes down to Blackshaw Brook, which flowed past the south side of the house near the junction with the River Croal. The hall was demolished in 1951. The growth of the textile industry around Darcy Lever was assisted by the availability of coal. By 1896 John Fletcher owned coal mines at Ladyshore, Little Lever; The Earl of Bradford had a coal mine at Great Lever and the Darcy Lever Coal Company and others had mines