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 was living in 1246, ancestor of the Levers of Little Lever, who held a share of the manor until the beginning of the 17th century. In the Lever of Great Lever are charters referring to the Lever family. Adam de Lever and his son Ellis attested a grant; no. 45. Ellis son of Adam de Lever granted to William his son and his heirs a portion of his land in Little Lever. The bounds began at 'the Langcestre' (alias Hanycestre) where Denebrook fell into the great water called Lever (alias Letoce); ascended the brook to a ditch dividing Little Lever