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 isolated system remains constant in time, as long as the system is free of friction and other non-conservative forces. In any real situation, frictional forces and other non-conservative forces are present, but in many cases their effects on the system are so small that the principle of conservation of mechanical energy can be used as a fair approximation. Though energy cannot be created or destroyed in an isolated system, it can be converted to another form of energy. In a mechanical system like a swinging pendulum subjected to the conservative gravitational force where frictional forces like air drag and friction