Grasshopper escapement to Harrison were poor, messy and short-lived. This meant that conventional clocks had to be stopped frequently for cleaning and oiling. Using his clean and absolutely stable grasshopper escapement Harrison began a series of long-term investigations into the performance of clocks, leading to his invention of the gridiron pendulum which counteracted the effects of expansion and contraction with changing temperature. The performance of his improved clocks in turn gave him an accurate, convenient standard against which to test his marine timekeepers. Harrison developed the grasshopper escapement from a conventional anchor escapement which he built for a turret clock to go
Mechanical energy nonconservative forces, like frictional forces, will be present, but often they are of negligible values and the mechanical energy's being constant can therefore be a useful approximation. In elastic collisions, the mechanical energy is conserved but in inelastic collisions, some mechanical energy is converted into heat. The equivalence between lost mechanical energy (dissipation) and an increase in temperature was discovered by James Prescott Joule. Many devices are used to convert mechanical energy to or from other forms of energy, e.g. an electric motor converts electrical energy to mechanical energy, an electric generator converts mechanical energy into electrical energy and a